[Tarantool-patches] [PATCH v6 08/25] Fix luacheck warnings in test/app-tap

sergeyb at tarantool.org sergeyb at tarantool.org
Fri May 29 18:09:08 MSK 2020


From: Sergey Bronnikov <sergeyb at tarantool.org>

Part of #4681

Reviewed-by: Vladislav Shpilevoy <v.shpilevoy at tarantool.org>
Reviewed-by: Igor Munkin <imun at tarantool.org>

Co-authored-by: Vladislav Shpilevoy <v.shpilevoy at tarantool.org>
Co-authored-by: Igor Munkin <imun at tarantool.org>
---
 .luacheckrc                                   |   3 +-
 test/app-tap/cfg.test.lua                     |   2 +-
 test/app-tap/clock.test.lua                   |   4 +-
 test/app-tap/console.test.lua                 |  16 +-
 test/app-tap/console_lua.test.lua             |  22 +-
 test/app-tap/csv.test.lua                     |  56 +-
 test/app-tap/debug.test.lua                   |  10 +-
 test/app-tap/errno.test.lua                   |  24 +-
 test/app-tap/fail_main.test.lua               |   6 +-
 .../gh-4761-json-per-call-options.test.lua    |  11 +-
 test/app-tap/http_client.test.lua             | 297 +++++------
 test/app-tap/iconv.test.lua                   |   6 +-
 test/app-tap/init_script.test.lua             |  14 +-
 test/app-tap/inspector.test.lua               |   5 +-
 test/app-tap/json.test.lua                    |   1 -
 test/app-tap/logger.test.lua                  |  21 +-
 test/app-tap/lua/serializer_test.lua          |  44 +-
 test/app-tap/minimal.test.lua                 |   4 +-
 test/app-tap/module_api.test.lua              |  12 +-
 test/app-tap/msgpackffi.test.lua              |   3 +-
 test/app-tap/pcall.test.lua                   |   6 +-
 test/app-tap/popen.test.lua                   |  35 +-
 test/app-tap/snapshot.test.lua                |  17 +-
 test/app-tap/string.test.lua                  | 502 +++++++++---------
 test/app-tap/tap.test.lua                     |  26 +-
 test/app-tap/tarantoolctl.test.lua            |  82 ++-
 test/app-tap/trigger.test.lua                 |  48 +-
 test/app-tap/yaml.test.lua                    |  16 +-
 28 files changed, 630 insertions(+), 663 deletions(-)

diff --git a/.luacheckrc b/.luacheckrc
index 78bb54adb..630834e16 100644
--- a/.luacheckrc
+++ b/.luacheckrc
@@ -7,7 +7,6 @@ exclude_files = {
     "build/**/*.lua",
     "src/box/lua/serpent.lua", -- third-party source code
     "test/app/*.test.lua",
-    "test/app-tap/lua/serializer_test.lua",
     "test/box/**/*.lua",
     "test/engine/*.lua",
     "test/engine_long/*.lua",
@@ -40,3 +39,5 @@ files["src/box/lua/console.lua"] = {globals = {"help"}, ignore = {"212"}}
 files["src/box/lua/net_box.lua"] = {globals = {"bit"}, ignore = {"431", "432"}}
 files["src/box/lua/schema.lua"] = {globals = {"tonumber64"}, ignore = {"431", "432"}}
 files["test/app/lua/fiber.lua"] = {globals = {"box_fiber_run_test"}}
+files["test/app-tap/lua/require_mod.lua"] = {globals = {"exports"}}
+files["test/app-tap/string.test.lua"] = {globals = {"utf8"}}
diff --git a/test/app-tap/cfg.test.lua b/test/app-tap/cfg.test.lua
index ba6b735ab..14e040f9f 100755
--- a/test/app-tap/cfg.test.lua
+++ b/test/app-tap/cfg.test.lua
@@ -12,7 +12,7 @@ test:plan(11)
 local nil_uuid = '00000000-0000-0000-0000-000000000000'
 local ok = pcall(box.cfg, {instance_uuid = nil_uuid})
 test:ok(not ok, 'nil instance UUID is not allowed')
-ok, err = pcall(box.cfg, {replicaset_uuid = nil_uuid})
+ok = pcall(box.cfg, {replicaset_uuid = nil_uuid})
 test:ok(not ok, 'nil replicaset UUID is not allowed')
 
 test:is(type(box.ctl), "table", "box.ctl is available before box.cfg")
diff --git a/test/app-tap/clock.test.lua b/test/app-tap/clock.test.lua
index fd1c4f272..d1ea4f0a8 100755
--- a/test/app-tap/clock.test.lua
+++ b/test/app-tap/clock.test.lua
@@ -1,7 +1,7 @@
 #!/usr/bin/env tarantool
 
-clock = require("clock")
-test = require("tap").test("csv")
+local clock = require("clock")
+local test = require("tap").test("csv")
 test:plan(10)
 test:ok(clock.realtime() > 0, "realtime")
 test:ok(clock.thread() > 0, "thread")
diff --git a/test/app-tap/console.test.lua b/test/app-tap/console.test.lua
index 4feadfa5e..454d5a892 100755
--- a/test/app-tap/console.test.lua
+++ b/test/app-tap/console.test.lua
@@ -5,7 +5,6 @@ local console = require('console')
 local socket = require('socket')
 local yaml = require('yaml')
 local fiber = require('fiber')
-local ffi = require('ffi')
 local log = require('log')
 local fio = require('fio')
 
@@ -19,7 +18,8 @@ os.remove(IPROTO_SOCKET)
 --
 local EOL = "\n...\n"
 
-test = tap.test("console")
+local test = tap.test("console")
+local _
 
 test:plan(80)
 
@@ -59,7 +59,8 @@ test:is(client:read(";"), 'true;', "pushed message")
 client:write('\\set output lua\n')
 client:read(";")
 
-long_func_f = nil
+local long_func_f
+-- luacheck: globals long_func (is called via client socket)
 function long_func()
     long_func_f = fiber.self()
     box.session.push('push')
@@ -95,12 +96,9 @@ test:is(#client:read(EOL) > 0, true, "_G")
 client:write("require('fiber').id()\n")
 local fid1 = yaml.decode(client:read(EOL))[1]
 local state = fiber.find(fid1).storage.console
-local server_info = state.client:peer()
 local client_info = state.client:name()
 test:is(client_info.host, client_info.host, "state.socker:peer().host")
 test:is(client_info.port, client_info.port, "state.socker:peer().port")
-server_info = nil
-client_info = nil
 
 -- Check console.delimiter()
 client:write("require('console').delimiter(';')\n")
@@ -233,13 +231,13 @@ box.cfg{listen = ''}
 os.remove(IPROTO_SOCKET)
 
 local s = console.listen('127.0.0.1:0')
-addr = s:name()
+local addr = s:name()
 test:is(addr.family, 'AF_INET', 'console.listen uri support')
 test:is(addr.host, '127.0.0.1', 'console.listen uri support')
 test:isnt(addr.port, 0, 'console.listen uri support')
 s:close()
 
-local s = console.listen('console://unix/:'..CONSOLE_SOCKET)
+s = console.listen('console://unix/:'..CONSOLE_SOCKET)
 addr = s:name()
 test:is(addr.family, 'AF_UNIX', 'console.listen uri support')
 test:is(addr.host, 'unix/', 'console.listen uri support')
@@ -279,7 +277,7 @@ box.session.on_disconnect(console_on_disconnect)
 box.session.on_auth(console_on_auth)
 
 -- check on_connect/on_disconnect/on_auth triggers
-local server = console.listen('console://unix/:'..CONSOLE_SOCKET)
+server = console.listen('console://unix/:'..CONSOLE_SOCKET)
 client = socket.tcp_connect("unix/", CONSOLE_SOCKET)
 _ = client:read(128)
 client:write("1\n")
diff --git a/test/app-tap/console_lua.test.lua b/test/app-tap/console_lua.test.lua
index 3ed6aad97..d3ba17779 100755
--- a/test/app-tap/console_lua.test.lua
+++ b/test/app-tap/console_lua.test.lua
@@ -13,7 +13,7 @@ local CONSOLE_SOCKET = 'console-lua.sock'
 --
 -- Set Lua output mode.
 local function set_lua_output(client, opts)
-    local opts = opts or {}
+    opts = opts or {}
     local mode = opts.block and 'lua,block' or 'lua'
     client:write(('\\set output %s\n'):format(mode))
     assert(client:read(EOL), 'true' .. EOL, 'set lua output mode')
@@ -57,8 +57,8 @@ end
 
 --
 -- Execute a list of statements, show requests and responses.
-local function execute_statements(test, client, statements, name)
-    test:test(name, function(test)
+local function execute_statements(testcase, client, statements, name)
+    testcase:test(name, function(test)
         test:plan(2 * #statements)
 
         for _, stmt in ipairs(statements) do
@@ -75,15 +75,15 @@ end
 
 --
 -- Execute a statement and verify its response.
-local function execute_and_verify(test, client, input, exp_output, name)
-    test:test(name, function(test)
+local function execute_and_verify(testcase, client, input, exp_output, name)
+    testcase:test(name, function(test)
         test:plan(2)
 
         local res = client:write(input .. '\n')
         test:ok(res ~= nil, ('-> [[%s]]'):format(input))
 
         local exp = exp_output .. EOL
-        local res = client:read(EOL)
+        res = client:read(EOL)
         test:is(res, exp, ('<- [[%s]]'):format(exp:gsub('\n', '\\n')))
     end)
 end
@@ -134,15 +134,15 @@ test:plan(#cases)
 local server, client = start_console()
 
 for _, case in ipairs(cases) do
-    test:test(case.name, function(test)
-        test:plan(3)
+    test:test(case.name, function(testcase)
+        testcase:plan(3)
 
-        execute_statements(test, client, totable(case.prepare), 'prepare')
+        execute_statements(testcase, client, totable(case.prepare), 'prepare')
 
         set_lua_output(client, case.opts)
-        execute_and_verify(test, client, case.input, case.expected, 'run')
+        execute_and_verify(testcase, client, case.input, case.expected, 'run')
 
-        execute_statements(test, client, totable(case.cleanup), 'cleanup')
+        execute_statements(testcase, client, totable(case.cleanup), 'cleanup')
     end)
 end
 
diff --git a/test/app-tap/csv.test.lua b/test/app-tap/csv.test.lua
index a7f17b1ea..eb180f95d 100755
--- a/test/app-tap/csv.test.lua
+++ b/test/app-tap/csv.test.lua
@@ -2,9 +2,9 @@
 
 local function table2str(t)
     local res = ""
-    for k, line in pairs(t) do
+    for _, line in pairs(t) do
         local s = ""
-        for k2, field in pairs(line) do
+        for _, field in pairs(line) do
             s = s .. '|' .. field .. '|\t'
         end
         res = res .. s .. '\n'
@@ -12,9 +12,9 @@ local function table2str(t)
     return res
 end
 
-local function myread(self, bytes) 
+local function myread(self, bytes)
     self.i = self.i + bytes
-    return self.v:sub(self.i - bytes + 1, self.i) 
+    return self.v:sub(self.i - bytes + 1, self.i)
 end
 local csv = require('csv')
 local fio = require('fio')
@@ -27,18 +27,18 @@ local test4_ans = '|123|\t|5|\t|92|\t|0|\t|0|\t\n|1|\t|12  34|\t|56|\t' ..
 local test5_ans = "|1|\t\n|23|\t|456|\t|abcac|\t|'multiword field 4'|\t\n" ..
                   "|none|\t|none|\t|0|\t\n||\t||\t||\t\n|aba|\t|adda|\t|f" ..
                   "3|\t|0|\t\n|local res = internal.pwrite(self.fh|\t|dat" ..
-                  "a|\t|len|\t|offset)|\t\n|iflag = bit.bor(iflag|\t|fio." .. 
+                  "a|\t|len|\t|offset)|\t\n|iflag = bit.bor(iflag|\t|fio." ..
                   "c.flag[ flag ])|\t\n||\t||\t||\t\n"
 local test6_ans = "|23|\t|456|\t|abcac|\t|'multiword field 4'|\t\n|none|" ..
-                  "\t|none|\t|0|\t\n||\t||\t||\t\n|aba|\t|adda|\t|f3|\t|" .. 
+                  "\t|none|\t|0|\t\n||\t||\t||\t\n|aba|\t|adda|\t|f3|\t|" ..
                   "0|\t\n|local res = internal.pwrite(self.fh|\t|data|\t" ..
                   "|len|\t|offset)|\t\n|iflag = bit.bor(iflag|\t|fio.c.f" ..
                   "lag[ flag ])|\t\n||\t||\t||\t\n"
 
-test = tap.test("csv")
+local test = tap.test("csv")
 test:plan(12)
 
-readable = {}
+local readable = {}
 readable.read = myread
 readable.v = "a,b\n1,\"ha\n\"\"ha\"\"\nha\"\n3,4\n"
 readable.i = 0
@@ -52,17 +52,17 @@ readable.v = ", \r\nkp\"\"v"
 readable.i = 0
 test:is(table2str(csv.load(readable, {chunk_size = 3})), test3_ans, "obj test3")
 
-tmpdir = fio.tempdir()
-file1 = fio.pathjoin(tmpdir, 'file.1')
-file2 = fio.pathjoin(tmpdir, 'file.2')
-file3 = fio.pathjoin(tmpdir, 'file.3')
-file4 = fio.pathjoin(tmpdir, 'file.4')
+local tmpdir = fio.tempdir()
+local file1 = fio.pathjoin(tmpdir, 'file.1')
+local file2 = fio.pathjoin(tmpdir, 'file.2')
+local file3 = fio.pathjoin(tmpdir, 'file.3')
+local file4 = fio.pathjoin(tmpdir, 'file.4')
 
 local f = fio.open(file1, { 'O_WRONLY', 'O_TRUNC', 'O_CREAT' }, tonumber('0777', 8))
 f:write("123 , 5  ,       92    , 0, 0\n" ..
         "1, 12  34, 56, \"quote , \", 66\nok")
 f:close()
-f = fio.open(file1, {'O_RDONLY'}) 
+f = fio.open(file1, {'O_RDONLY'})
 test:is(table2str(csv.load(f, {chunk_size = 10})), test4_ans, "fio test1")
 f:close()
 
@@ -77,31 +77,31 @@ f:write("1\n23,456,abcac,\'multiword field 4\'\n" ..
         ",,"
 )
 f:close()
-f = fio.open(file2, {'O_RDONLY'}) 
+f = fio.open(file2, {'O_RDONLY'})
 --symbol by symbol reading
-test:is(table2str(csv.load(f, {chunk_size = 1})), test5_ans, "fio test2") 
+test:is(table2str(csv.load(f, {chunk_size = 1})), test5_ans, "fio test2")
 f:close()
 
-f = fio.open(file2, {'O_RDONLY'}) 
-opts = {chunk_size = 7, skip_head_lines = 1}
+f = fio.open(file2, {'O_RDONLY'})
+local opts = {chunk_size = 7, skip_head_lines = 1}
 --7 symbols per chunk
-test:is(table2str(csv.load(f, opts)), test6_ans, "fio test3") 
+test:is(table2str(csv.load(f, opts)), test6_ans, "fio test3")
 f:close()
 
-t = {
-    {'quote" d', ',and, comma', 'both " of " t,h,e,m'}, 
-    {'"""', ',","'}, 
-    {'mul\nti\nli\r\nne\n\n', 'field'},
-    {""},
-    {'"'},
-    {"\n"}
+local t = {
+          {'quote" d', ',and, comma', 'both " of " t,h,e,m'},
+          {'"""', ',","'},
+          {'mul\nti\nli\r\nne\n\n', 'field'},
+          {""},
+          {'"'},
+          {"\n"}
 }
 
 f = require("fio").open(file3, { "O_WRONLY", "O_TRUNC" , "O_CREAT"}, 0x1FF)
 csv.dump(t, {}, f)
 f:close()
-f = fio.open(file3, {'O_RDONLY'}) 
-t2 = csv.load(f, {chunk_size = 5})
+f = fio.open(file3, {'O_RDONLY'})
+local t2 = csv.load(f, {chunk_size = 5})
 f:close()
 
 test:is(table2str(t), table2str(t2), "test roundtrip")
diff --git a/test/app-tap/debug.test.lua b/test/app-tap/debug.test.lua
index 0d199e55b..0f9b881f0 100755
--- a/test/app-tap/debug.test.lua
+++ b/test/app-tap/debug.test.lua
@@ -44,7 +44,7 @@ print(('debug.sourcefile() => %s; %s'):format(tostring(result), tostring(err)))
 assert(result == box.NULL, 'debug.sourcefile() returns box.NULL')
 assert(err == nil, 'debug.sourcefile() returns no error')
 
-local result, err = conn:call('debug.sourcedir')
+result, err = conn:call('debug.sourcedir')
 print(('debug.sourcedir() => %s; %s'):format(tostring(result), tostring(err)))
 assert(result == '.', 'debug.sourcedir() returns "."')
 assert(err == nil, 'debug.sourcedir() returns no error')
@@ -58,10 +58,10 @@ print('When running lua code from console')
 print('==================================')
 -- debug.sourcefile() returns cwd when running within console
 for _, test in ipairs(tests) do
-    local cmd = string.format('%s -e "%s; os.exit(0)"', TNTBIN, test)
-    print('Exec: '..cmd)
+    local cmdline = string.format('%s -e "%s; os.exit(0)"', TNTBIN, test)
+    print('Exec: '..cmdline)
     io.flush()
-    assert(os.execute(cmd) == 0, string.format('cmd: "%s" must execute successfully', cmd))
+    assert(os.execute(cmdline) == 0, string.format('cmd: "%s" must execute successfully', cmdline))
 end
 
 local fio = require('fio')
@@ -74,7 +74,7 @@ if not dirstat then
 end
 assert(dirstat:is_dir(), dirname..' must be a directory')
 
-local cmd = TNTBIN..' '..filename
+cmd = TNTBIN..' '..filename
 print('======================================')
 print('When running lua code from script file')
 print('======================================')
diff --git a/test/app-tap/errno.test.lua b/test/app-tap/errno.test.lua
index 5fd8eaca4..41f8c7d15 100755
--- a/test/app-tap/errno.test.lua
+++ b/test/app-tap/errno.test.lua
@@ -6,16 +6,16 @@ local errno = require('errno')
 local test = tap.test("errno")
 
 test:plan(1)
-test:test("primary", function(test)
-    test:plan(10)
-    test:is(type(errno), "table", "type of table")
-    test:ok(errno.EINVAL ~= nil, "errno.EINVAL is available")
-    test:ok(errno.EBADF ~= nil , "errno.EBADF is available" )
-    test:ok(errno(0) ~= nil, "errno set to 0")
-    test:is(errno(errno.EBADF), 0, "setting errno.EBADF")
-    test:is(errno(), errno.EBADF, "checking errno.EBADF")
-    test:is(errno(errno.EINVAL), errno.EBADF, "setting errno.EINVAL")
-    test:is(errno(), errno.EINVAL, "checking errno.EINVAL")
-    test:is(errno.strerror(), "Invalid argument", "checking strerror without argument")
-    test:is(errno.strerror(errno.EBADF), "Bad file descriptor", "checking strerror with argument")
+test:test("primary", function(testcase)
+    testcase:plan(10)
+    testcase:is(type(errno), "table", "type of table")
+    testcase:ok(errno.EINVAL ~= nil, "errno.EINVAL is available")
+    testcase:ok(errno.EBADF ~= nil , "errno.EBADF is available" )
+    testcase:ok(errno(0) ~= nil, "errno set to 0")
+    testcase:is(errno(errno.EBADF), 0, "setting errno.EBADF")
+    testcase:is(errno(), errno.EBADF, "checking errno.EBADF")
+    testcase:is(errno(errno.EINVAL), errno.EBADF, "setting errno.EINVAL")
+    testcase:is(errno(), errno.EINVAL, "checking errno.EINVAL")
+    testcase:is(errno.strerror(), "Invalid argument", "checking strerror without argument")
+    testcase:is(errno.strerror(errno.EBADF), "Bad file descriptor", "checking strerror with argument")
 end)
diff --git a/test/app-tap/fail_main.test.lua b/test/app-tap/fail_main.test.lua
index f8c45bf6f..3fe0971eb 100755
--- a/test/app-tap/fail_main.test.lua
+++ b/test/app-tap/fail_main.test.lua
@@ -7,7 +7,7 @@ local tarantool_bin = arg[-1]
 
 test:plan(1)
 
-function run_script(code)
+local function run_script(code)
     local dir = fio.tempdir()
     local script_path = fio.pathjoin(dir, 'script.lua')
     local script = fio.open(script_path, {'O_CREAT', 'O_WRONLY', 'O_APPEND'},
@@ -16,7 +16,7 @@ function run_script(code)
     script:close()
     local output_file = fio.pathjoin(fio.cwd(), 'out.txt')
     local cmd = [[/bin/sh -c 'cd "%s" && "%s" ./script.lua 0> %s 2> %s']]
-    local code = os.execute(
+    code = os.execute(
         string.format(cmd, dir, tarantool_bin, output_file, output_file)
     )
     fio.rmtree(dir)
@@ -30,7 +30,7 @@ end
 -- gh-4382: an error in main script should be handled gracefully,
 -- with proper logging.
 --
-local code, output = run_script("error('Error in the main script')")
+local _, output = run_script("error('Error in the main script')")
 
 test:ok(output:match("fatal error, exiting the event loop"),
         "main script error is handled gracefully")
diff --git a/test/app-tap/gh-4761-json-per-call-options.test.lua b/test/app-tap/gh-4761-json-per-call-options.test.lua
index 1fb24744e..bd710b76f 100755
--- a/test/app-tap/gh-4761-json-per-call-options.test.lua
+++ b/test/app-tap/gh-4761-json-per-call-options.test.lua
@@ -13,23 +13,24 @@ local res = tap.test('gh-4761-json-per-call-options', function(test)
     test:plan(2)
 
     -- Preparation code: call :decode() with a custom option.
-    local ok, err = pcall(json.decode, '{"foo": {"bar": 1}}',
+    local ok = pcall(json.decode, '{"foo": {"bar": 1}}',
                           {decode_max_depth = 1})
     assert(not ok, 'expect "too many nested data structures" error')
 
     -- Verify that the instance option remains unchanged.
     local exp_res = {foo = {bar = 1}}
-    local ok, res = pcall(json.decode, '{"foo": {"bar": 1}}')
+    local res
+    ok, res = pcall(json.decode, '{"foo": {"bar": 1}}')
     test:is_deeply({ok, res}, {true, exp_res},
                    'json instance settings remain unchanged after :decode()')
 
     -- Same check for json.encode.
     local nan = 1/0
-    local ok, err = pcall(json.encode, {a = nan},
+    ok = pcall(json.encode, {a = nan},
                           {encode_invalid_numbers = false})
     assert(not ok, 'expected "number must not be NaN or Inf" error')
-    local exp_res = '{"a":inf}'
-    local ok, res = pcall(json.encode, {a = nan})
+    exp_res = '{"a":inf}'
+    ok, res = pcall(json.encode, {a = nan})
     test:is_deeply({ok, res}, {true, exp_res},
                    'json instance settings remain unchanged after :encode()')
 end)
diff --git a/test/app-tap/http_client.test.lua b/test/app-tap/http_client.test.lua
index b85b605cf..b44876b39 100755
--- a/test/app-tap/http_client.test.lua
+++ b/test/app-tap/http_client.test.lua
@@ -22,8 +22,8 @@ local function merge(...)
     return res
 end
 
-local function start_server(test, sock_family, sock_addr)
-    test:diag("starting HTTP server on %s...", sock_addr)
+local function start_server(testcase, sock_family, sock_addr)
+    testcase:diag("starting HTTP server on %s...", sock_addr)
     local arg, url, opts
     if sock_family == 'AF_INET' then
         arg = string.format("--inet %s", sock_addr)
@@ -39,51 +39,51 @@ local function start_server(test, sock_family, sock_addr)
     local cmd = string.format("%s/test/app-tap/httpd.py %s",
                               TARANTOOL_SRC_DIR, arg)
     local server = io.popen(cmd)
-    test:is(server:read("*l"), "heartbeat", "server started")
-    test:diag("trying to connect to %s", url)
+    testcase:is(server:read("*l"), "heartbeat", "server started")
+    testcase:diag("trying to connect to %s", url)
     local r
-    for i=1,10 do
+    for _=1,10 do
         r = client.get(url, merge(opts, {timeout = 0.01}))
         if r.status == 200 then
             break
         end
         fiber.sleep(0.01)
     end
-    test:is(r.status, 200, "connection is ok")
+    testcase:is(r.status, 200, "connection is ok")
     if r.status ~= 200 then
         os.exit(1)
     end
     return server, url, opts
 end
 
-local function stop_server(test, server)
-    test:diag("stopping HTTP server")
+local function stop_server(testcase, server)
+    testcase:diag("stopping HTTP server")
     server:close()
 end
 
-local function test_http_client(test, url, opts)
-    test:plan(11)
+local function test_http_client(testcase, url, opts)
+    testcase:plan(11)
 
     -- gh-4136: confusing httpc usage error message
     local ok, err = pcall(client.request, client)
     local usage_err = "request(method, url[, body, [options]])"
-    test:is_deeply({ok, err:split(': ')[2]}, {false, usage_err},
+    testcase:is_deeply({ok, err:split(': ')[2]}, {false, usage_err},
                    "test httpc usage error")
 
-    test:isnil(rawget(_G, 'http'), "global namespace is not polluted");
-    test:isnil(rawget(_G, 'http.client'), "global namespace is not polluted");
+    testcase:isnil(rawget(_G, 'http'), "global namespace is not polluted");
+    testcase:isnil(rawget(_G, 'http.client'), "global namespace is not polluted");
     local r = client.get(url, opts)
-    test:is(r.status, 200, 'simple 200')
-    test:is(r.reason, 'Ok', '200 - Ok')
-    test:is(r.proto[1], 1, 'proto major http 1.1')
-    test:is(r.proto[2], 1, 'proto major http 1.1')
-    test:ok(r.body:match("hello") ~= nil, "body")
-    test:ok(tonumber(r.headers["content-length"]) > 0,
+    testcase:is(r.status, 200, 'simple 200')
+    testcase:is(r.reason, 'Ok', '200 - Ok')
+    testcase:is(r.proto[1], 1, 'proto major http 1.1')
+    testcase:is(r.proto[2], 1, 'proto major http 1.1')
+    testcase:ok(r.body:match("hello") ~= nil, "body")
+    testcase:ok(tonumber(r.headers["content-length"]) > 0,
         "content-length > 0")
-    test:is(client.get("http://localhost:1/").status, 595, 'cannot connect')
+    testcase:is(client.get("http://localhost:1/").status, 595, 'cannot connect')
 
-    local r = client.request('GET', url, nil, opts)
-    test:is(r.status, 200, 'request')
+    r = client.request('GET', url, nil, opts)
+    testcase:is(r.status, 200, 'request')
 
     -- XXX: enable after resolving of gh-4180: httpc: redirects
     -- are broken with libcurl-7.30 and older
@@ -118,36 +118,36 @@ end
 -- gh-3955: Check that httpc module doesn't redefine http headers
 --          set explicitly by the caller.
 --
-local function test_http_client_headers_redefine(test, url, opts)
-    test:plan(9)
-    local opts = table.deepcopy(opts)
+local function test_http_client_headers_redefine(testcase, url, opts)
+    testcase:plan(9)
+    opts = table.deepcopy(opts)
     -- Test defaults
     opts.headers = {['Connection'] = nil, ['Accept'] = nil}
     local r = client.post(url, nil, opts)
-    test:is(r.status, 200, 'simple 200')
-    test:is(r.headers['connection'], 'close', 'Default Connection header')
-    test:is(r.headers['accept'], '*/*', 'Default Accept header for POST request')
+    testcase:is(r.status, 200, 'simple 200')
+    testcase:is(r.headers['connection'], 'close', 'Default Connection header')
+    testcase:is(r.headers['accept'], '*/*', 'Default Accept header for POST request')
     -- Test that in case of conflicting headers, user variant is
     -- prefered
     opts.headers={['Connection'] = 'close'}
     opts.keepalive_idle = 2
     opts.keepalive_interval = 1
-    local r = client.get(url, opts)
-    test:is(r.status, 200, 'simple 200')
-    test:is(r.headers['connection'], 'close', 'Redefined Connection header')
-    test:is(r.headers['keep_alive'], 'timeout=2',
+    r = client.get(url, opts)
+    testcase:is(r.status, 200, 'simple 200')
+    testcase:is(r.headers['connection'], 'close', 'Redefined Connection header')
+    testcase:is(r.headers['keep_alive'], 'timeout=2',
             'Automatically set Keep-Alive header')
     -- Test that user-defined Connection and Acept headers
     -- are used
     opts.headers={['Connection'] = 'Keep-Alive', ['Accept'] = 'text/html'}
-    local r = client.get(url, opts)
-    test:is(r.status, 200, 'simple 200')
-    test:is(r.headers['accept'], 'text/html', 'Redefined Accept header')
-    test:is(r.headers['connection'], 'Keep-Alive', 'Redefined Connection header')
+    r = client.get(url, opts)
+    testcase:is(r.status, 200, 'simple 200')
+    testcase:is(r.headers['accept'], 'text/html', 'Redefined Accept header')
+    testcase:is(r.headers['connection'], 'Keep-Alive', 'Redefined Connection header')
 end
 
-local function test_cancel_and_errinj(test, url, opts)
-    test:plan(3)
+local function test_cancel_and_errinj(testcase, url, opts)
+    testcase:plan(3)
     local ch = fiber.channel(1)
     local http = client:new()
     local func  = function(fopts)
@@ -156,31 +156,30 @@ local function test_cancel_and_errinj(test, url, opts)
     local f = fiber.create(func, opts)
     f:cancel()
     local r = ch:get()
-    test:ok(r.status == 408 and string.find(r.reason, "Timeout"),
+    testcase:ok(r.status == 408 and string.find(r.reason, "Timeout"),
                     "After cancel fiber timeout is returned")
     r = http:get(url, merge(opts, {timeout = 0.0001}))
-    test:ok(r.status == 408 and string.find(r.reason, "Timeout"),
+    testcase:ok(r.status == 408 and string.find(r.reason, "Timeout"),
                                                        "Timeout check")
     local errinj = box.error.injection
     errinj.set('ERRINJ_HTTP_RESPONSE_ADD_WAIT', true)
     local topts = merge(opts, {timeout = 1200})
-    f = fiber.create(func, topts)
+    fiber.create(func, topts)
     r = ch:get()
-    test:is(r.status, 200, "No hangs in errinj")
+    testcase:is(r.status, 200, "No hangs in errinj")
     errinj.set('ERRINJ_HTTP_RESPONSE_ADD_WAIT', false)
 end
 
-local function test_post_and_get(test, url, opts)
-    test:plan(21)
+local function test_post_and_get(testcase, url, opts)
+    testcase:plan(21)
 
     local http = client.new()
-    test:ok(http ~= nil, "client is created")
+    testcase:ok(http ~= nil, "client is created")
 
     local headers = { header1 = "1", header2 = "2" }
     local my_body = { key = "value" }
     local json_body = json.encode(my_body)
     local responses = {}
-    local data = {a = 'b'}
     headers['Content-Type'] = 'application/json'
     local fibers = 7
     local ch = fiber.channel(fibers)
@@ -213,70 +212,69 @@ local function test_post_and_get(test, url, opts)
         responses.absent_get = http:get(url .. 'absent', opts)
         ch:put(1)
     end)
-    for i=1,fibers do
+    for _=1,fibers do
         ch:get()
     end
     local r = responses.good_get
-    test:is(r.status, 200, "GET: default http code page exists")
-    test:is(r.body, "hello world", "GET: default right body")
+    testcase:is(r.status, 200, "GET: default http code page exists")
+    testcase:is(r.body, "hello world", "GET: default right body")
 
     r = responses.get2
-    test:is(r.status, 200, "GET: http code page exists")
-    test:is(r.body, "abc", "GET: right body")
+    testcase:is(r.status, 200, "GET: http code page exists")
+    testcase:is(r.body, "abc", "GET: right body")
 
     r = responses.absent_get
-    test:is(r.status, 500, "GET: absent method http code page exists")
-    test:is(r.reason, 'Unknown', '500 - Unknown')
-    test:is(r.body, "No such method", "GET: absent method right body")
+    testcase:is(r.status, 500, "GET: absent method http code page exists")
+    testcase:is(r.reason, 'Unknown', '500 - Unknown')
+    testcase:is(r.body, "No such method", "GET: absent method right body")
 
     r = responses.empty_post
-    test:is(r.status, 200, "POST: good status")
-    test:ok(r.headers['header1'] == headers.header1 and
+    testcase:is(r.status, 200, "POST: good status")
+    testcase:ok(r.headers['header1'] == headers.header1 and
         r.headers['header2'] == headers.header2, "POST: good headers")
-    test:isnil(r.body, "POST: empty body")
+    testcase:isnil(r.body, "POST: empty body")
 
     r = responses.good_post
-    test:is(r.status, 200, "POST: good status")
-    test:ok(r.headers['header1'] == headers.header1 and
+    testcase:is(r.status, 200, "POST: good status")
+    testcase:ok(r.headers['header1'] == headers.header1 and
         r.headers['header2'] == headers.header2, "POST: good headers")
-    test:is(r.body, json_body, "POST: body")
+    testcase:is(r.body, json_body, "POST: body")
 
     r = responses.good_put
-    test:is(r.status, 200, "PUT: good status")
-    test:ok(r.headers['header'] == headers.header and
+    testcase:is(r.status, 200, "PUT: good status")
+    testcase:ok(r.headers['header'] == headers.header and
         r.headers['header2'] == headers.header2, "PUT: good headers")
 
     r = responses.bad_get
-    test:is(r.status, 404, "GET: http page not exists")
-    test:is(r.reason, 'Unknown', '404 - Unknown')
-    test:isnt(r.body:len(), 0, "GET: not empty body page not exists")
-    test:ok(string.find(r.body, "Not Found"),
+    testcase:is(r.status, 404, "GET: http page not exists")
+    testcase:is(r.reason, 'Unknown', '404 - Unknown')
+    testcase:isnt(r.body:len(), 0, "GET: not empty body page not exists")
+    testcase:ok(string.find(r.body, "Not Found"),
                 "GET: right body page not exists")
 
     local st = http:stat()
-    test:ok(st.sockets_added == st.sockets_deleted and
+    testcase:ok(st.sockets_added == st.sockets_deleted and
         st.active_requests == 0,
         "stats checking")
 end
 
-local function test_errors(test)
-    test:plan(2)
+local function test_errors(testcase)
+    testcase:plan(2)
     local http = client:new()
     local status, err = pcall(http.get, http, "htp://mail.ru")
-    test:ok(not status and string.find(json.encode(err),
+    testcase:ok(not status and string.find(json.encode(err),
                         "Unsupported protocol"),
                         "GET: exception on bad protocol")
     status, err = pcall(http.post, http, "htp://mail.ru", "")
-    test:ok(not status and string.find(json.encode(err),
+    testcase:ok(not status and string.find(json.encode(err),
                         "Unsupported protocol"),
                         "POST: exception on bad protocol")
-    local r = http:get("http://do_not_exist_8ffad33e0cb01e6a01a03d00089e71e5b2b7e9930dfcba.ru")
 end
 
 -- gh-3679 Check that opts.headers values can be strings only.
 -- gh-4281 Check that opts.headers can be a table and opts.headers
 -- keys can be strings only.
-local function test_request_headers(test, url, opts)
+local function test_request_headers(testcase, url, opts)
     local exp_err_bad_opts_headers = 'opts.headers should be a table'
     local exp_err_bad_key = 'opts.headers keys should be strings'
     local exp_err_bad_value = 'opts.headers values should be strings'
@@ -350,53 +348,53 @@ local function test_request_headers(test, url, opts)
             exp_err = exp_err_bad_value,
         },
     }
-    test:plan(#cases)
+    testcase:plan(#cases)
 
     local http = client:new()
 
     for _, case in ipairs(cases) do
-        local opts = merge(table.copy(opts), case.opts)
+        opts = merge(table.copy(opts), case.opts)
         local ok, err = pcall(http.get, http, url, opts)
         if case.postrequest_check ~= nil then
             case.postrequest_check(opts)
         end
         if case.exp_err == nil then
             -- expect success
-            test:ok(ok, case[1])
+            testcase:ok(ok, case[1])
         else
             -- expect fail
             assert(type(err) == 'string')
             err = err:gsub('^builtin/[a-z._]+.lua:[0-9]+: ', '')
-            test:is_deeply({ok, err}, {false, case.exp_err}, case[1])
+            testcase:is_deeply({ok, err}, {false, case.exp_err}, case[1])
         end
     end
 end
 
-local function test_headers(test, url, opts)
-    test:plan(21)
+local function test_headers(testcase, url, opts)
+    testcase:plan(21)
     local http = client:new()
     local r = http:get(url .. 'headers', opts)
-    test:is(type(r.headers["set-cookie"]), 'string', "set-cookie check")
-    test:ok(r.headers["set-cookie"]:match("likes=cheese"), "set-cookie check")
-    test:ok(r.headers["set-cookie"]:match("age = 17"), "set-cookie check")
-    test:is(r.headers["content-type"], "application/json", "content-type check")
-    test:is(r.headers["my_header"], "value1,value2", "other header check")
-    test:isnil(r.headers["11200ok"], "http status line not included in headers")
-    test:is(r.cookies["likes"][1], "cheese", "cookie value check")
-    test:ok(r.cookies["likes"][2][1]:match("Expires"), "cookie option check")
-    test:ok(r.cookies["likes"][2][3]:match("HttpOnly"), "cookie option check")
-    test:is(r.cookies["age"][1], "17", "cookie value check")
-    test:is(#r.cookies["age"][2], 1, "cookie option check")
-    test:is(r.cookies["age"][2][1], "Secure", "cookie option check")
-    test:ok(r.cookies["good_name"] ~= nil , "cookie name check")
-    test:ok(r.cookies["bad at name"] == nil , "cookie name check")
-    test:ok(r.cookies["badname"] == nil , "cookie name check")
-    test:ok(r.cookies["badcookie"] == nil , "cookie name check")
-    test:isnil(r.headers["very_very_very_long_headers_name1"], "no long header name")
-    test:is(r.headers["very_very_very_long_headers_name"], "true", "truncated name")
+    testcase:is(type(r.headers["set-cookie"]), 'string', "set-cookie check")
+    testcase:ok(r.headers["set-cookie"]:match("likes=cheese"), "set-cookie check")
+    testcase:ok(r.headers["set-cookie"]:match("age = 17"), "set-cookie check")
+    testcase:is(r.headers["content-type"], "application/json", "content-type check")
+    testcase:is(r.headers["my_header"], "value1,value2", "other header check")
+    testcase:isnil(r.headers["11200ok"], "http status line not included in headers")
+    testcase:is(r.cookies["likes"][1], "cheese", "cookie value check")
+    testcase:ok(r.cookies["likes"][2][1]:match("Expires"), "cookie option check")
+    testcase:ok(r.cookies["likes"][2][3]:match("HttpOnly"), "cookie option check")
+    testcase:is(r.cookies["age"][1], "17", "cookie value check")
+    testcase:is(#r.cookies["age"][2], 1, "cookie option check")
+    testcase:is(r.cookies["age"][2][1], "Secure", "cookie option check")
+    testcase:ok(r.cookies["good_name"] ~= nil , "cookie name check")
+    testcase:ok(r.cookies["bad at name"] == nil , "cookie name check")
+    testcase:ok(r.cookies["badname"] == nil , "cookie name check")
+    testcase:ok(r.cookies["badcookie"] == nil , "cookie name check")
+    testcase:isnil(r.headers["very_very_very_long_headers_name1"], "no long header name")
+    testcase:is(r.headers["very_very_very_long_headers_name"], "true", "truncated name")
     opts["max_header_name_length"] = 64
-    local r = http:get(url .. 'headers', opts)
-    test:is(r.headers["very_very_very_long_headers_name1"], "true", "truncated max_header_name_length")
+    r = http:get(url .. 'headers', opts)
+    testcase:is(r.headers["very_very_very_long_headers_name1"], "true", "truncated max_header_name_length")
     opts["max_header_name_length"] = nil
 
     -- Send large headers.
@@ -406,26 +404,25 @@ local function test_headers(test, url, opts)
     -- "${hname}: ${hvalue}" is 8192 bytes length
     local hvalue = string.rep('x', MAX_HEADER_NAME - hname:len() - 2)
     local headers = {[hname] = hvalue}
-    local r = http:post(url, nil, merge(opts, {headers = headers}))
-    test:is(r.headers[hname], hvalue, '8192 bytes header: success')
+    r = http:post(url, nil, merge(opts, {headers = headers}))
+    testcase:is(r.headers[hname], hvalue, '8192 bytes header: success')
 
     -- "${hname}: ${hvalue}" is 8193 bytes length
     local exp_err = 'header is too large'
-    local hvalue = string.rep('x', MAX_HEADER_NAME - hname:len() - 1)
-    local headers = {[hname] = hvalue}
+    hvalue = string.rep('x', MAX_HEADER_NAME - hname:len() - 1)
+    headers = {[hname] = hvalue}
     local ok, err = pcall(http.post, http, url, nil,
                           merge(opts, {headers = headers}))
-    test:is_deeply({ok, tostring(err)}, {false, exp_err},
+    testcase:is_deeply({ok, tostring(err)}, {false, exp_err},
                    '8193 KiB header: error')
 end
 
-local function test_special_methods(test, url, opts)
-    test:plan(14)
+local function test_special_methods(testcase, url, opts)
+    testcase:plan(14)
     local http = client.new()
     local responses = {}
     local fibers = 7
     local ch = fiber.channel(fibers)
-    local _
     fiber.create(function()
         responses.patch_data = http:patch(url, "{\"key\":\"val\"}", opts)
         ch:put(1)
@@ -454,39 +451,35 @@ local function test_special_methods(test, url, opts)
         responses.custom_data = http:request("CUSTOM", url, nil, opts)
         ch:put(1)
     end)
-    for i = 1, fibers do
+    for _ = 1, fibers do
         ch:get()
     end
 
-    test:is(responses.patch_data.status, 200, "HTTP:PATCH request")
-    test:ok(json.decode(responses.patch_data.body).key == "val",
+    testcase:is(responses.patch_data.status, 200, "HTTP:PATCH request")
+    testcase:ok(json.decode(responses.patch_data.body).key == "val",
         "HTTP:PATCH request content")
-    test:is(responses.delete_data.status, 200, "HTTP:DELETE request")
-    test:ok(responses.delete_data.headers.method == "DELETE",
+    testcase:is(responses.delete_data.status, 200, "HTTP:DELETE request")
+    testcase:ok(responses.delete_data.headers.method == "DELETE",
         "HTTP:DELETE request content")
-    test:is(responses.options_data.status, 200, "HTTP:OPTIONS request")
-    test:ok(responses.options_data.headers.method == "OPTIONS",
+    testcase:is(responses.options_data.status, 200, "HTTP:OPTIONS request")
+    testcase:ok(responses.options_data.headers.method == "OPTIONS",
         "HTTP:OPTIONS request content")
-    test:is(responses.head_data.status, 200, "HTTP:HEAD request code")
-    test:ok(responses.head_data.headers.method == "HEAD",
+    testcase:is(responses.head_data.status, 200, "HTTP:HEAD request code")
+    testcase:ok(responses.head_data.headers.method == "HEAD",
         "HTTP:HEAD request content")
-    test:is(responses.connect_data.status, 200, "HTTP:CONNECT request")
-    test:ok(responses.connect_data.headers.method == "CONNECT",
+    testcase:is(responses.connect_data.status, 200, "HTTP:CONNECT request")
+    testcase:ok(responses.connect_data.headers.method == "CONNECT",
         "HTTP:OPTIONS request content")
-    test:is(responses.trace_data.status, 200, "HTTP:TRACE request")
-    test:ok(responses.trace_data.headers.method == "TRACE",
+    testcase:is(responses.trace_data.status, 200, "HTTP:TRACE request")
+    testcase:ok(responses.trace_data.headers.method == "TRACE",
         "HTTP:TRACE request content")
-    test:is(responses.custom_data.status, 400, "HTTP:CUSTOM request")
-    test:ok(responses.custom_data.headers.method == "CUSTOM",
+    testcase:is(responses.custom_data.status, 400, "HTTP:CUSTOM request")
+    testcase:ok(responses.custom_data.headers.method == "CUSTOM",
         "HTTP:CUSTOM request content")
 end
 
-local function test_concurrent(test, url, opts)
-    test:plan(3)
-    local http = client.new()
-    local headers = { my_header = "1", my_header2 = "2" }
-    local my_body = { key = "value" }
-    local json_body = json.encode(my_body)
+local function test_concurrent(testcase, url, opts)
+    testcase:plan(3)
     local num_test = 10
     local num_load = 10
     local curls   = { }
@@ -497,7 +490,7 @@ local function test_concurrent(test, url, opts)
         headers["My-header" .. i] = "my-value"
     end
 
-    for i = 1, num_test do
+    for _ = 1, num_test do
         table.insert(curls, {
             url = url,
             http = client.new(),
@@ -515,7 +508,7 @@ local function test_concurrent(test, url, opts)
     -- Creating concurrent clients
     for i=1,num_test do
         local obj = curls[i]
-        for j=1,num_load do
+        for _=1,num_load do
             fiber.create(function()
                 local r = obj.http:post(obj.url, obj.body, merge(opts, {
                     headers = obj.headers,
@@ -540,13 +533,11 @@ local function test_concurrent(test, url, opts)
     end
     local ok_sockets_added = true
     local ok_active = true
-    local ok_timeout = true
     local ok_req = true
 
     -- Join test
     local rest = num_test
     while true do
-        local ticks = 0
         for i = 1, num_load do
             local obj = curls[i]
             -- checking that stats in concurrent are ok
@@ -577,23 +568,23 @@ local function test_concurrent(test, url, opts)
             break
         end
     end
-    test:is(ok_req, true, "All requests are ok")
-    test:ok(ok_sockets_added, "free sockets")
-    test:ok(ok_active, "no active requests")
+    testcase:is(ok_req, true, "All requests are ok")
+    testcase:ok(ok_sockets_added, "free sockets")
+    testcase:ok(ok_active, "no active requests")
 end
 
-function run_tests(test, sock_family, sock_addr)
-    test:plan(11)
-    local server, url, opts = start_server(test, sock_family, sock_addr)
-    test:test("http.client", test_http_client, url, opts)
-    test:test("http.client headers redefine", test_http_client_headers_redefine,
+local function run_tests(testcase, sock_family, sock_addr)
+    testcase:plan(11)
+    local server, url, opts = start_server(testcase, sock_family, sock_addr)
+    testcase:test("http.client", test_http_client, url, opts)
+    testcase:test("http.client headers redefine", test_http_client_headers_redefine,
               url, opts)
-    test:test("cancel and errinj", test_cancel_and_errinj, url .. 'long_query', opts)
-    test:test("basic http post/get", test_post_and_get, url, opts)
-    test:test("errors", test_errors)
-    test:test("request_headers", test_request_headers, url, opts)
-    test:test("headers", test_headers, url, opts)
-    test:test("special methods", test_special_methods, url, opts)
+    testcase:test("cancel and errinj", test_cancel_and_errinj, url .. 'long_query', opts)
+    testcase:test("basic http post/get", test_post_and_get, url, opts)
+    testcase:test("errors", test_errors)
+    testcase:test("request_headers", test_request_headers, url, opts)
+    testcase:test("headers", test_headers, url, opts)
+    testcase:test("special methods", test_special_methods, url, opts)
     if sock_family == 'AF_UNIX' and jit.os ~= "Linux" then
         --
         -- BSD-based operating systems (including OS X) will fail
@@ -604,25 +595,25 @@ function run_tests(test, sock_family, sock_addr)
         -- however, is fine - instead of returning ECONNEREFUSED
         -- it will suspend connect() until backlog is processed.
         --
-        test:skip("concurrent")
+        testcase:skip("concurrent")
     else
-        test:test("concurrent", test_concurrent, url, opts)
+        testcase:test("concurrent", test_concurrent, url, opts)
     end
-    stop_server(test, server)
+    stop_server(testcase, server)
 end
 
 test:plan(2)
 
-test:test("http over AF_INET", function(test)
+test:test("http over AF_INET", function(testcase)
     local s = socketlib('AF_INET', 'SOCK_STREAM', 0)
     s:bind('127.0.0.1', 0)
     local host = s:name().host
     local port = s:name().port
     s:close()
-    run_tests(test, 'AF_INET', string.format("%s:%d", host, port))
+    run_tests(testcase, 'AF_INET', string.format("%s:%d", host, port))
 end)
 
-test:test("http over AF_UNIX", function(test)
+test:test("http over AF_UNIX", function(testcase)
     local path = os.tmpname()
     os.remove(path)
     local status = pcall(client.get, 'http://localhost/', {unix_socket = path})
@@ -630,7 +621,7 @@ test:test("http over AF_UNIX", function(test)
         -- Unix domain sockets are not supported, skip the test.
         return
     end
-    run_tests(test, 'AF_UNIX', path)
+    run_tests(testcase, 'AF_UNIX', path)
     os.remove(path)
 end)
 
diff --git a/test/app-tap/iconv.test.lua b/test/app-tap/iconv.test.lua
index 6f6a04b14..b4e8e7339 100755
--- a/test/app-tap/iconv.test.lua
+++ b/test/app-tap/iconv.test.lua
@@ -3,7 +3,7 @@
 local tap   = require('tap')
 local iconv = require('iconv')
 
-test = tap.test("iconv")
+local test = tap.test("iconv")
 test:plan(11)
 
 local simple_str  = 'ascii string'
@@ -34,7 +34,7 @@ test:is(c8_1251(c1251_16(c16_16be(c16be_8(cyrillic_str)))), cyrillic_str,
         'complex multi-format conversion')
 
 -- test huge string
-huge_str = string.rep(cyrillic_str, 50)
+local huge_str = string.rep(cyrillic_str, 50)
 
 test:is(c16be_8(c8_16be(huge_str)), huge_str, "huge string")
 
@@ -42,7 +42,7 @@ local stat, err = pcall(iconv.new, 'NOT EXISTS', 'UTF-8')
 test:is(stat, false, 'error was thrown on bad encoding')
 test:ok(err:match('Invalid') ~= nil, 'correct error')
 
-local stat, err = pcall(c_ascii_8, cyrillic_str)
+stat, err = pcall(c_ascii_8, cyrillic_str)
 test:is(stat, false, 'error was thrown on sequence')
 test:ok(err:match('Incomplete multibyte sequence') ~= nil, 'correct error')
 
diff --git a/test/app-tap/init_script.test.lua b/test/app-tap/init_script.test.lua
index 155f149a7..5831ffa77 100755
--- a/test/app-tap/init_script.test.lua
+++ b/test/app-tap/init_script.test.lua
@@ -9,14 +9,14 @@ box.cfg{
     log="tarantool.log"
 }
 
-yaml = require('yaml')
-fiber = require('fiber')
+local yaml = require('yaml')
+local fiber = require('fiber')
 
 if box.space.tweedledum ~= nil then
     box.space.space1:drop()
 end
 
-space = box.schema.space.create('tweedledum')
+local space = box.schema.space.create('tweedledum')
 space:create_index('primary', { type = 'hash' })
 
 print[[
@@ -24,7 +24,7 @@ print[[
 -- Access to box.cfg from init script
 --
 ]]
-t = {}
+local t = {}
 
 for k,v in pairs(box.cfg) do
     if k == 'listen' then
@@ -44,7 +44,7 @@ local function do_insert()
     space:insert{1, 2, 4, 8}
 end
 
-fiber1 = fiber.create(do_insert)
+fiber.create(do_insert)
 
 print[[
 --
@@ -71,12 +71,12 @@ print[[
 -- Check that require function(math.floor) reachable in the init script
 --
 ]]
-floor = require("math").floor
+local floor = require("math").floor
 print(floor(0.5))
 print(floor(0.9))
 print(floor(1.1))
 
-mod = require('require_mod')
+local mod = require('require_mod')
 print(mod.test(10, 15))
 --
 -- A test case for https://github.com/tarantool/tarantool/issues/53
diff --git a/test/app-tap/inspector.test.lua b/test/app-tap/inspector.test.lua
index ed10020a2..cda3eda2c 100755
--- a/test/app-tap/inspector.test.lua
+++ b/test/app-tap/inspector.test.lua
@@ -1,9 +1,6 @@
 #!/usr/bin/env tarantool
 
-local socket = require('socket')
-
-test_run = require('test_run')
-inspector = test_run.new()
+local inspector = require('test_run').new()
 
 print('create instance')
 print(inspector:cmd("create server replica with rpl_master=default, script='box/box.lua'\n"))
diff --git a/test/app-tap/json.test.lua b/test/app-tap/json.test.lua
index fadfc74ec..186d6ad46 100755
--- a/test/app-tap/json.test.lua
+++ b/test/app-tap/json.test.lua
@@ -2,7 +2,6 @@
 
 package.path = "lua/?.lua;"..package.path
 
-local ffi = require('ffi')
 local tap = require('tap')
 local common = require('serializer_test')
 
diff --git a/test/app-tap/logger.test.lua b/test/app-tap/logger.test.lua
index 492d5ea0b..87cde953b 100755
--- a/test/app-tap/logger.test.lua
+++ b/test/app-tap/logger.test.lua
@@ -26,7 +26,7 @@ end
 log.info(message)
 local line = file:read()
 test:is(line:sub(-message:len()), message, "message")
-s, err = pcall(json.decode, line)
+local s = pcall(json.decode, line)
 test:ok(not s, "plain")
 --
 -- gh-700: Crash on calling log.info() with formatting characters
@@ -45,7 +45,7 @@ test:is(file:read():match('I>%s+(.*)'), '{"key":"value"}', "table is handled as
 log.info({message="value"})
 test:is(file:read():match('I>%s+(.*)'), '{"message":"value"}', "table is handled as json")
 
-function help() log.info("gh-2340: %s %s", 'help') end
+local function help() log.info("gh-2340: %s %s", 'help') end
 
 xpcall(help, function(err)
     test:ok(err:match("bad argument #3"), "found error string")
@@ -56,34 +56,34 @@ file:close()
 
 test:ok(log.pid() >= 0, "pid()")
 
--- logger uses 'debug', try to set it to nil
+-- luacheck: ignore (logger uses 'debug', try to set it to nil)
 debug = nil
 log.info("debug is nil")
 debug = require('debug')
 
 test:ok(log.info(true) == nil, 'check tarantool crash (gh-2516)')
 
-s, err = pcall(box.cfg, {log_format='json', log="syslog:identity:tarantool"})
+s = pcall(box.cfg, {log_format='json', log="syslog:identity:tarantool"})
 test:ok(not s, "check json not in syslog")
 
 box.cfg{log=filename,
     memtx_memory=107374182,
     log_format = "json"}
 
-local file = io.open(filename)
+file = io.open(filename)
 while file:read() do
 end
 
 log.error("error")
 
-local line = file:read()
+line = file:read()
 message = json.decode(line)
 test:is(type(message), 'table', "json valid in log.error")
 test:is(message.level, "ERROR", "check type error")
 test:is(message.message, "error", "check error message")
 
 log.info({key="value", level=48})
-local line = file:read()
+line = file:read()
 message = json.decode(line)
 test:is(type(message), 'table', "json valid in log.info")
 test:is(message.level, "INFO", "check type info")
@@ -91,7 +91,7 @@ test:is(message.message, nil, "check message is nil")
 test:is(message.key, "value", "custom table encoded")
 
 log.info('this is "')
-local line = file:read()
+line = file:read()
 message = json.decode(line)
 test:is(message.message, "this is \"", "check message with escaped character")
 
@@ -101,13 +101,14 @@ line = file:read()
 test:ok(line:len() < 20000, "big line truncated")
 
 log.info("json")
-local line = file:read()
+line = file:read()
 message = json.decode(line)
 test:is(message.message, "json", "check message with internal key word")
 log.log_format("plain")
 log.info("hello")
 line = file:read()
 test:ok(not line:match("{"), "log change format")
+local e
 s, e = pcall(log.log_format, "non_format")
 test:ok(not s, "bad format")
 file:close()
@@ -120,7 +121,7 @@ file = fio.open(filename)
 while file == nil do file = fio.open(filename) fiber.sleep(0.0001) end
 line = file:read()
 while line == nil or line == ""  do line = file:read() fiber.sleep(0.0001) end
-index = line:find('\n')
+local index = line:find('\n')
 line = line:sub(1, index)
 message = json.decode(line)
 test:is(message.message, "log file has been reopened", "check message after log.rotate()")
diff --git a/test/app-tap/lua/serializer_test.lua b/test/app-tap/lua/serializer_test.lua
index 2a668f898..fdbfb3b24 100644
--- a/test/app-tap/lua/serializer_test.lua
+++ b/test/app-tap/lua/serializer_test.lua
@@ -2,7 +2,7 @@ local ffi = require('ffi')
 
 local function rt(test, s, x, t)
     local buf1 = s.encode(x)
-    local x1, offset1 = s.decode(buf1)
+    local x1 = s.decode(buf1)
     local xstr
     if type(x) == "table" then
         xstr = "table"
@@ -189,8 +189,6 @@ local function test_double(test, s)
     ss.cfg{decode_invalid_numbers = true}
     rt(test, s, nan)
     rt(test, s, inf)
-
-    ss = nil
 end
 
 local function test_decimal(test, s)
@@ -258,14 +256,14 @@ local function test_table(test, s, is_array, is_map)
     test:ok(is_map(s.encode({k1 = 'v1', k2 = 'v2', k3 = 'v3'})), "map is map")
 
     -- utf-8 pairs
-    rt(test, s, {Метапеременная = { 'Метазначение' }})
+    rt(test, s, {['Метапеременная'] = { 'Метазначение' }})
     rt(test, s, {test = { 'Результат' }})
 
     local arr = setmetatable({1, 2, 3, k1 = 'v1', k2 = 'v2', 4, 5},
         { __serialize = 'seq'})
     local map = setmetatable({1, 2, 3, 4, 5}, { __serialize = 'map'})
     local obj = setmetatable({}, {
-        __serialize = function(x) return 'serialize' end
+        __serialize = function() return 'serialize' end
     })
 
     -- __serialize on encode
@@ -306,14 +304,12 @@ local function test_table(test, s, is_array, is_map)
     -- string (from __serialize hook)
     test:is(ss.decode(ss.encode(obj)), "serialize", "object load __serialize")
 
-    ss = nil
-
     --
     -- decode_save_metatables
     --
 
-    local arr = {1, 2, 3}
-    local map = {k1 = 'v1', k2 = 'v2', k3 = 'v3'}
+    arr = {1, 2, 3}
+    map = {k1 = 'v1', k2 = 'v2', k3 = 'v3'}
 
     ss = s.new()
     ss.cfg{decode_save_metatables = false}
@@ -325,14 +321,12 @@ local function test_table(test, s, is_array, is_map)
         "array save __serialize")
     test:is(getmetatable(ss.decode(ss.encode(map))).__serialize, "map",
         "map save __serialize")
-    ss = nil
-
 
     --
     -- encode_sparse_convert / encode_sparse_ratio / encode_sparse_safe
     --
 
-    local ss = s.new()
+    ss = s.new()
 
     ss.cfg{encode_sparse_ratio = 2, encode_sparse_safe = 10}
 
@@ -359,8 +353,6 @@ local function test_table(test, s, is_array, is_map)
     -- array
     test:ok(is_array(ss.encode({1, 2, 3, 4, 5, [100] = 100})),
         "sparse safe 2")
-
-    ss = nil
 end
 
 local function test_ucdata(test, s)
@@ -374,9 +366,9 @@ local function test_ucdata(test, s)
     local ctype = ffi.typeof('struct serializer_cdata_test')
     ffi.metatype(ctype, {
         __index = {
-            __serialize = function(obj) return 'unpack' end,
+            __serialize = function() return 'unpack' end,
         },
-        __tostring = function(obj) return 'tostring' end
+        __tostring = function() return 'tostring' end
     });
 
     local cdata = ffi.new(ctype)
@@ -409,8 +401,6 @@ local function test_ucdata(test, s)
     test:istable(ss.decode(ss.encode(udata)), 'udata  hook priority')
     -- gh-1226: luaL_convertfield should ignore __serialize hook for ctypes
     test:like(ss.decode(ss.encode(ctype)), 'ctype<struct', 'ctype __serialize')
-
-    ss = nil
 end
 
 local function test_depth(test, s)
@@ -433,12 +423,12 @@ local function test_depth(test, s)
     s.cfg({encode_deep_as_nil = false})
 
     local t = nil
-    for i = 1, max_depth + 1 do t = {t} end
-    local ok, err = pcall(s.encode, t)
+    for i = 1, max_depth + 1 do t = {t} end -- luacheck: ignore
+    local ok = pcall(s.encode, t)
     test:ok(not ok, "too deep encode depth")
 
     s.cfg({encode_max_depth = max_depth + 1})
-    ok, err = pcall(s.encode, t)
+    ok = pcall(s.encode, t)
     test:ok(ok, "no throw in a corner case")
 
     s.cfg({encode_deep_as_nil = deep_as_nil, encode_max_depth = max_depth})
@@ -483,21 +473,21 @@ local function test_decode_buffer(test, s)
     test:plan(#cases)
 
     for _, case in ipairs(cases) do
-        test:test(case[1], function(test)
-            test:plan(4)
+        test:test(case[1], function(testcase)
+            testcase:plan(4)
             local args_len = table.maxn(case.args)
             local res, res_buf = case.func(unpack(case.args, 1, args_len))
-            test:is_deeply(res, case.exp_res, 'verify result')
+            testcase:is_deeply(res, case.exp_res, 'verify result')
             local buf = case.args[1]
             local rewind = res_buf - buf
-            test:is(rewind, case.exp_rewind, 'verify resulting buffer')
+            testcase:is(rewind, case.exp_rewind, 'verify resulting buffer')
             -- test:iscdata() is not sufficient here, because it
             -- ignores 'const' qualifier (because of using
             -- ffi.istype()).
-            test:is(type(res_buf), 'cdata', 'verify resulting buffer type')
+            testcase:is(type(res_buf), 'cdata', 'verify resulting buffer type')
             local buf_ctype = tostring(ffi.typeof(buf))
             local res_buf_ctype = tostring(ffi.typeof(res_buf))
-            test:is(res_buf_ctype, buf_ctype, 'verify resulting buffer ctype')
+            testcase:is(res_buf_ctype, buf_ctype, 'verify resulting buffer ctype')
         end)
     end
 end
diff --git a/test/app-tap/minimal.test.lua b/test/app-tap/minimal.test.lua
index e44a0f6a7..8b261a03e 100755
--- a/test/app-tap/minimal.test.lua
+++ b/test/app-tap/minimal.test.lua
@@ -24,13 +24,13 @@ os.execute("tarantool ./script-args.lua 1 2 3")
 --
 -- LUA_PATH and LUA_CPATH argument handling
 --
-local script = io.open('script-path.lua', 'w')
+script = io.open('script-path.lua', 'w')
 script:write([[
 print(package.path)
 os.exit(0)
 ]])
 script:close()
-local script = io.open('script-cpath.lua', 'w')
+script = io.open('script-cpath.lua', 'w')
 script:write([[
 print(package.cpath)
 os.exit(0)
diff --git a/test/app-tap/module_api.test.lua b/test/app-tap/module_api.test.lua
index a6658cc61..d7be56a9b 100755
--- a/test/app-tap/module_api.test.lua
+++ b/test/app-tap/module_api.test.lua
@@ -5,7 +5,7 @@ local fio = require('fio')
 box.cfg{log = "tarantool.log"}
 -- Use BUILDDIR passed from test-run or cwd when run w/o
 -- test-run to find test/app-tap/module_api.{so,dylib}.
-build_path = os.getenv("BUILDDIR") or '.'
+local build_path = os.getenv("BUILDDIR") or '.'
 package.cpath = fio.pathjoin(build_path, 'test/app-tap/?.so'   ) .. ';' ..
                 fio.pathjoin(build_path, 'test/app-tap/?.dylib') .. ';' ..
                 package.cpath
@@ -17,10 +17,10 @@ local function test_pushcdata(test, module)
     local gc_counter = 0;
     local ct = ffi.typeof('struct module_api_test')
     ffi.metatype(ct, {
-        __tostring = function(obj)
+        __tostring = function()
             return 'ok'
         end;
-        __gc = function(obj)
+        __gc = function()
             gc_counter = gc_counter + 1;
         end
     })
@@ -33,7 +33,7 @@ local function test_pushcdata(test, module)
     test:is(ctid, ctid2, 'checkcdata type')
     test:is(ptr, ptr2, 'checkcdata value')
     test:is(gc_counter, 0, 'pushcdata gc')
-    obj = nil
+    obj = nil -- luacheck: ignore
     collectgarbage('collect')
     test:is(gc_counter, 1, 'pushcdata gc')
 end
@@ -116,7 +116,7 @@ local function test_iscallable(test, module)
     end
 end
 
-local test = require('tap').test("module_api", function(test)
+require('tap').test("module_api", function(test)
     test:plan(24)
     local status, module = pcall(require, 'module_api')
     test:is(status, true, "module")
@@ -138,7 +138,7 @@ local test = require('tap').test("module_api", function(test)
         end
     end
 
-    local status, msg = pcall(module.check_error)
+    local _, msg = pcall(module.check_error)
     test:like(msg, 'luaT_error', 'luaT_error')
 
     test:test("pushcdata", test_pushcdata, module)
diff --git a/test/app-tap/msgpackffi.test.lua b/test/app-tap/msgpackffi.test.lua
index 0ee5f5edc..058b74f3d 100755
--- a/test/app-tap/msgpackffi.test.lua
+++ b/test/app-tap/msgpackffi.test.lua
@@ -4,7 +4,6 @@ package.path = "lua/?.lua;"..package.path
 
 local tap = require('tap')
 local common = require('serializer_test')
-local ffi = require('ffi')
 
 local function is_map(s)
     local b = string.byte(string.sub(s, 1, 1))
@@ -76,7 +75,7 @@ local function test_other(test, s)
     --
     local function check_depth(depth_to_try)
         local t = nil
-        for i = 1, depth_to_try do t = {t} end
+        for _ = 1, depth_to_try do t = {t} end
         t = s.decode_unchecked(s.encode(t))
         local level = 0
         while t ~= nil do level = level + 1 t = t[1] end
diff --git a/test/app-tap/pcall.test.lua b/test/app-tap/pcall.test.lua
index 30163a41a..3ae16c8aa 100755
--- a/test/app-tap/pcall.test.lua
+++ b/test/app-tap/pcall.test.lua
@@ -12,7 +12,7 @@ box.cfg{
     log="tarantool.log",
     memtx_memory=107374182,
 }
-function pcalltest()
+local function pcalltest()
     local ERRMSG = "module 'some_invalid_module' not found"
     local status, msg = pcall(require, 'some_invalid_module')
     if status == false and msg ~= nil and msg:match(ERRMSG) ~= nil then
@@ -27,10 +27,10 @@ local status, msg = xpcall(pcalltest, function(msg)
 end)
 print('pcall inside xpcall:', status, msg)
 
-local status, msg = pcall(function() error('some message') end)
+status, msg = pcall(function() error('some message') end)
 print('pcall with Lua error():', status, msg:match('some message'))
 
-local status, msg = pcall(function()
+status, msg = pcall(function()
     box.error(box.error.ILLEGAL_PARAMS, 'some message')
 end)
 print('pcall with box.error():', status, msg)
diff --git a/test/app-tap/popen.test.lua b/test/app-tap/popen.test.lua
index e1aef9ef9..8bec6aab6 100755
--- a/test/app-tap/popen.test.lua
+++ b/test/app-tap/popen.test.lua
@@ -90,12 +90,13 @@ local function test_trivial_echo_output(test)
     test:ok(is_dead, 'the process is killed after close()')
 
     -- Verify that :close() is idempotent.
-    local res, err = ph:close()
+    res, err = ph:close()
     test:is_deeply({res, err}, {true, nil}, 'close() is idempotent')
 
     -- Sending a signal using a closed handle gives an error.
     local exp_err = 'popen: attempt to operate on a closed handle'
-    local ok, err = pcall(ph.signal, ph, popen.signal.SIGTERM)
+    local ok
+    ok, err = pcall(ph.signal, ph, popen.signal.SIGTERM)
     test:is_deeply({ok, err.type, tostring(err)},
                    {false, 'IllegalParams', exp_err},
                    'signal() on closed handle gives an error')
@@ -195,28 +196,28 @@ local function test_read_write(test)
     test:is_deeply({res, err}, {true, nil}, 'write() succeeds')
     local ok = ph:shutdown({stdin = true})
     test:ok(ok, 'shutdown() succeeds')
-    local res, err = ph:read()
+    res, err = ph:read()
     test:is_deeply({res, err}, {payload, nil}, 'read() from stdout succeeds')
 
     ph:close()
 
     -- The script copies data from stdin to stderr.
-    local script = 'prompt=""; read -r prompt; printf "$prompt" 1>&2'
-    local ph = popen.shell(script, 'Rw')
+    script = 'prompt=""; read -r prompt; printf "$prompt" 1>&2'
+    ph = popen.shell(script, 'Rw')
 
     -- Write to stdin, read from stderr.
-    local res, err = ph:write(payload .. '\n')
+    res, err = ph:write(payload .. '\n')
     test:is_deeply({res, err}, {true, nil}, 'write() succeeds')
-    local ok = ph:shutdown({stdin = true})
+    ok = ph:shutdown({stdin = true})
     test:ok(ok, 'shutdown() succeeds')
-    local res, err = ph:read({stderr = true})
+    res, err = ph:read({stderr = true})
     test:is_deeply({res, err}, {payload, nil}, 'read() from stderr succeeds')
 
     ph:close()
 
     -- The same script: copy from stdin to stderr.
-    local script = 'prompt=""; read -r prompt; printf "$prompt" 1>&2'
-    local ph = popen.shell(script, 'Rw')
+    script = 'prompt=""; read -r prompt; printf "$prompt" 1>&2'
+    ph = popen.shell(script, 'Rw')
 
     -- Ensure that read waits for data and does not return
     -- prematurely.
@@ -226,7 +227,7 @@ local function test_read_write(test)
         res_w, err_w = ph:write(payload .. '\n')
         ph:shutdown({stdin = true})
     end)
-    local res, err = ph:read({stderr = true})
+    res, err = ph:read({stderr = true})
     test:is_deeply({res_w, err_w}, {true, nil}, 'write() succeeds')
     test:is_deeply({res, err}, {payload, nil}, 'read() from stderr succeeds')
 
@@ -251,10 +252,10 @@ local function test_read_timeout(test)
                    'timeout error')
 
     -- Write and read after the timeout error.
-    local res, err = ph:write(payload .. '\n')
+    res, err = ph:write(payload .. '\n')
     test:is_deeply({res, err}, {true, nil}, 'write data')
     ph:shutdown({stdin = true})
-    local res, err = ph:read()
+    res, err = ph:read()
     test:is_deeply({res, err}, {payload, nil}, 'read data')
 
     ph:close()
@@ -294,13 +295,13 @@ local function test_shutdown(test)
     test:plan(9)
 
     -- Verify std* status.
-    local function test_stream_status(test, ph, pstream, exp_pstream)
-        test:plan(6)
+    local function test_stream_status(testcase, ph, pstream, exp_pstream)
+        testcase:plan(6)
         local info = ph:info()
         for _, s in ipairs({'stdin', 'stdout', 'stderr'}) do
             local exp_status = s == pstream and exp_pstream or nil
-            test:is(ph[s], exp_status, ('%s open'):format(s))
-            test:is(info[s], exp_status, ('%s open'):format(s))
+            testcase:is(ph[s], exp_status, ('%s open'):format(s))
+            testcase:is(info[s], exp_status, ('%s open'):format(s))
         end
     end
 
diff --git a/test/app-tap/snapshot.test.lua b/test/app-tap/snapshot.test.lua
index 587f8279b..6cae662c6 100755
--- a/test/app-tap/snapshot.test.lua
+++ b/test/app-tap/snapshot.test.lua
@@ -3,7 +3,6 @@
 local math = require('math')
 local fiber = require('fiber')
 local tap = require('tap')
-local ffi = require('ffi')
 local fio = require('fio')
 
 box.cfg{ log="tarantool.log", memtx_memory=107374182}
@@ -75,18 +74,18 @@ snap_chan:get()
 test:ok(true, 'gh-695: avoid overwriting tuple data necessary for smfree()')
 
 -------------------------------------------------------------------------------
--- gh-1185: Crash in matras_touch in snapshot_daemon.test 
+-- gh-1185: Crash in matras_touch in snapshot_daemon.test
 -------------------------------------------------------------------------------
 
 local s1 = box.schema.create_space('test1', { engine = 'memtx'})
-local i1 = s1:create_index('test', { type = 'tree', parts = {1, 'unsigned'} })
+s1:create_index('test', { type = 'tree', parts = {1, 'unsigned'} })
 
 local s2 = box.schema.create_space('test2', { engine = 'memtx'})
-local i2 = s2:create_index('test', { type = 'tree', parts = {1, 'unsigned'} })
+s2:create_index('test', { type = 'tree', parts = {1, 'unsigned'} })
 
 for i = 1,1000 do s1:insert{i, i, i} end
 
-local snap_chan = fiber.channel()
+snap_chan = fiber.channel()
 fiber.create(function () box.snapshot() snap_chan:put(true) end)
 
 fiber.sleep(0)
@@ -126,11 +125,11 @@ local function gh1094()
             break
         end
     end
-    local sf, mf = pcall(box.snapshot)
-    for i, f in pairs(files) do
+    local sf = pcall(box.snapshot)
+    for _, f in pairs(files) do
         f:close()
     end
-    local ss, ms = pcall(box.snapshot)
+    local ss = pcall(box.snapshot)
     test:ok(not sf and ss, msg)
 end
 gh1094()
@@ -141,7 +140,7 @@ box.snapshot()
 box.snapshot()
 box.snapshot()
 test:ok(true, 'No crash for second snapshot w/o any changes')
-files = fio.glob(box.cfg.memtx_dir .. '/*.snap')
+local files = fio.glob(box.cfg.memtx_dir .. '/*.snap')
 table.sort(files)
 fio.unlink(files[#files])
 box.snapshot()
diff --git a/test/app-tap/string.test.lua b/test/app-tap/string.test.lua
index 02a1a84d7..bd4db6e43 100755
--- a/test/app-tap/string.test.lua
+++ b/test/app-tap/string.test.lua
@@ -5,40 +5,40 @@ local test = tap.test("string extensions")
 
 test:plan(7)
 
-test:test("split", function(test)
-    test:plan(10)
+test:test("split", function(testcase)
+    testcase:plan(10)
 
     -- testing basic split (works over gsplit)
-    test:ok(not pcall(string.split, "", ""), "empty separator")
-    test:ok(not pcall(string.split, "a", ""), "empty separator")
-    test:is_deeply((""):split("z"), {""},  "empty split")
-    test:is_deeply(("a"):split("a"), {"", ""}, "split self")
-    test:is_deeply(
+    testcase:ok(not pcall(string.split, "", ""), "empty separator")
+    testcase:ok(not pcall(string.split, "a", ""), "empty separator")
+    testcase:is_deeply((""):split("z"), {""},  "empty split")
+    testcase:is_deeply(("a"):split("a"), {"", ""}, "split self")
+    testcase:is_deeply(
         (" 1 2  3  "):split(),
         {"1", "2", "3"},
         "complex split on empty separator"
     )
-    test:is_deeply(
+    testcase:is_deeply(
         (" 1 2  3  "):split(" "),
         {"", "1", "2", "", "3", "", ""},
         "complex split on space separator"
     )
-    test:is_deeply(
+    testcase:is_deeply(
         (" 1 2  \n\n\n\r\t\n3  "):split(),
         {"1", "2", "3"},
         "complex split on empty separator"
     )
-    test:is_deeply(
+    testcase:is_deeply(
         ("a*bb*c*ddd"):split("*"),
         {"a", "bb", "c", "ddd"},
         "another * separator"
     )
-    test:is_deeply(
+    testcase:is_deeply(
         ("dog:fred:bonzo:alice"):split(":", 2),
         {"dog", "fred", "bonzo:alice"},
         "testing max separator"
     )
-    test:is_deeply(
+    testcase:is_deeply(
         ("///"):split("/"),
         {"", "", "", ""},
         "testing splitting on one char"
@@ -46,231 +46,231 @@ test:test("split", function(test)
 end)
 
 -- gh-2214 - string.ljust()/string.rjust() Lua API
-test:test("ljust/rjust/center", function(test)
-    test:plan(18)
+test:test("ljust/rjust/center", function(testcase)
+    testcase:plan(18)
 
-    test:is(("help"):ljust(0),  "help", "ljust, length 0, do nothing")
-    test:is(("help"):rjust(0),  "help", "rjust, length 0, do nothing")
-    test:is(("help"):center(0), "help", "center, length 0, do nothing")
+    testcase:is(("help"):ljust(0),  "help", "ljust, length 0, do nothing")
+    testcase:is(("help"):rjust(0),  "help", "rjust, length 0, do nothing")
+    testcase:is(("help"):center(0), "help", "center, length 0, do nothing")
 
-    test:is(("help"):ljust(3),  "help", "ljust, length 3, do nothing")
-    test:is(("help"):rjust(3),  "help", "rjust, length 3, do nothing")
-    test:is(("help"):center(3), "help", "center, length 3, do nothing")
+    testcase:is(("help"):ljust(3),  "help", "ljust, length 3, do nothing")
+    testcase:is(("help"):rjust(3),  "help", "rjust, length 3, do nothing")
+    testcase:is(("help"):center(3), "help", "center, length 3, do nothing")
 
-    test:is(("help"):ljust(5),  "help ", "ljust, length 5, one extra charachter")
-    test:is(("help"):rjust(5),  " help", "rjust, length 5, one extra charachter")
-    test:is(("help"):center(5), "help ", "center, length 5, one extra charachter")
+    testcase:is(("help"):ljust(5),  "help ", "ljust, length 5, one extra charachter")
+    testcase:is(("help"):rjust(5),  " help", "rjust, length 5, one extra charachter")
+    testcase:is(("help"):center(5), "help ", "center, length 5, one extra charachter")
 
-    test:is(("help"):ljust(6),  "help  ", "ljust, length 6, two extra charachters")
-    test:is(("help"):rjust(6),  "  help", "rjust, length 6, two extra charachters")
-    test:is(("help"):center(6), " help ", "center, length 6, two extra charachters")
+    testcase:is(("help"):ljust(6),  "help  ", "ljust, length 6, two extra charachters")
+    testcase:is(("help"):rjust(6),  "  help", "rjust, length 6, two extra charachters")
+    testcase:is(("help"):center(6), " help ", "center, length 6, two extra charachters")
 
-    test:is(("help"):ljust(6, '.'),  "help..", "ljust, length 6, two extra charachters, custom fill char")
-    test:is(("help"):rjust(6, '.'),  "..help", "rjust, length 6, two extra charachters, custom fill char")
-    test:is(("help"):center(6, '.'), ".help.", "center, length 6, two extra charachters, custom fill char")
+    testcase:is(("help"):ljust(6, '.'),  "help..", "ljust, length 6, two extra charachters, custom fill char")
+    testcase:is(("help"):rjust(6, '.'),  "..help", "rjust, length 6, two extra charachters, custom fill char")
+    testcase:is(("help"):center(6, '.'), ".help.", "center, length 6, two extra charachters, custom fill char")
     local errmsg = "%(char expected, got string%)"
     local _, err = pcall(function() ("help"):ljust(6, "XX") end)
-    test:ok(err and err:match(errmsg), "wrong params")
+    testcase:ok(err and err:match(errmsg), "wrong params")
     _, err = pcall(function() ("help"):rjust(6, "XX") end)
-    test:ok(err and err:match(errmsg), "wrong params")
+    testcase:ok(err and err:match(errmsg), "wrong params")
     _, err = pcall(function() ("help"):center(6, "XX") end)
-    test:ok(err and err:match(errmsg), "wrong params")
+    testcase:ok(err and err:match(errmsg), "wrong params")
 end)
 
 -- gh-2215 - string.startswith()/string.endswith() Lua API
-test:test("startswith/endswith", function(test)
-    test:plan(21)
-
-    test:ok((""):startswith(""),      "empty+empty startswith")
-    test:ok((""):endswith(""),        "empty+empty endswith")
-    test:ok(not (""):startswith("a"), "empty+non-empty startswith")
-    test:ok(not (""):endswith("a"),   "empty+non-empty endswith")
-    test:ok(("a"):startswith(""),     "non-empty+empty startswith")
-    test:ok(("a"):endswith(""),       "non-empty+empty endswith")
-
-    test:ok(("12345"):startswith("123")            , "simple startswith")
-    test:ok(("12345"):startswith("123", 1, 5)      , "startswith with good begin/end")
-    test:ok(("12345"):startswith("123", 1, 3)      , "startswith with good begin/end")
-    test:ok(("12345"):startswith("123", -5, 3)     , "startswith with good negative begin/end")
-    test:ok(("12345"):startswith("123", -5, -3)    , "startswith with good negative begin/end")
-    test:ok(not ("12345"):startswith("123", 2, 5)  , "bad startswith with good begin/end")
-    test:ok(not ("12345"):startswith("123", 1, 2)  , "bad startswith with good begin/end")
-
-    test:ok(("12345"):endswith("345")              , "simple endswith")
-    test:ok(("12345"):endswith("345", 1, 5)        , "endswith with good begin/end")
-    test:ok(("12345"):endswith("345", 3, 5)        , "endswith with good begin/end")
-    test:ok(("12345"):endswith("345", -3, 5)       , "endswith with good begin/end")
-    test:ok(("12345"):endswith("345", -3, -1)      , "endswith with good begin/end")
-    test:ok(not ("12345"):endswith("345", 1, 4)    , "bad endswith with good begin/end")
-    test:ok(not ("12345"):endswith("345", 4, 5)    , "bad endswith with good begin/end")
+test:test("startswith/endswith", function(testcase)
+    testcase:plan(21)
+
+    testcase:ok((""):startswith(""),      "empty+empty startswith")
+    testcase:ok((""):endswith(""),        "empty+empty endswith")
+    testcase:ok(not (""):startswith("a"), "empty+non-empty startswith")
+    testcase:ok(not (""):endswith("a"),   "empty+non-empty endswith")
+    testcase:ok(("a"):startswith(""),     "non-empty+empty startswith")
+    testcase:ok(("a"):endswith(""),       "non-empty+empty endswith")
+
+    testcase:ok(("12345"):startswith("123")            , "simple startswith")
+    testcase:ok(("12345"):startswith("123", 1, 5)      , "startswith with good begin/end")
+    testcase:ok(("12345"):startswith("123", 1, 3)      , "startswith with good begin/end")
+    testcase:ok(("12345"):startswith("123", -5, 3)     , "startswith with good negative begin/end")
+    testcase:ok(("12345"):startswith("123", -5, -3)    , "startswith with good negative begin/end")
+    testcase:ok(not ("12345"):startswith("123", 2, 5)  , "bad startswith with good begin/end")
+    testcase:ok(not ("12345"):startswith("123", 1, 2)  , "bad startswith with good begin/end")
+
+    testcase:ok(("12345"):endswith("345")              , "simple endswith")
+    testcase:ok(("12345"):endswith("345", 1, 5)        , "endswith with good begin/end")
+    testcase:ok(("12345"):endswith("345", 3, 5)        , "endswith with good begin/end")
+    testcase:ok(("12345"):endswith("345", -3, 5)       , "endswith with good begin/end")
+    testcase:ok(("12345"):endswith("345", -3, -1)      , "endswith with good begin/end")
+    testcase:ok(not ("12345"):endswith("345", 1, 4)    , "bad endswith with good begin/end")
+    testcase:ok(not ("12345"):endswith("345", 4, 5)    , "bad endswith with good begin/end")
 
     local _, err = pcall(function() ("help"):startswith({'n', 1}) end)
-    test:ok(err and err:match("%(string expected, got table%)"), "wrong params")
+    testcase:ok(err and err:match("%(string expected, got table%)"), "wrong params")
 end)
 
-test:test("hex", function(test)
-    test:plan(2)
-    test:is(string.hex("hello"), "68656c6c6f", "hex non-empty string")
-    test:is(string.hex(""), "", "hex empty string")
+test:test("hex", function(testcase)
+    testcase:plan(2)
+    testcase:is(string.hex("hello"), "68656c6c6f", "hex non-empty string")
+    testcase:is(string.hex(""), "", "hex empty string")
 end)
 
-test:test("fromhex", function(test)
-    test:plan(11)
-    test:is(string.fromhex("48656c6c6f"), "Hello", "from hex to bin")
-    test:is(string.fromhex("4c696e7578"), "Linux", "from hex to bin")
-    test:is(string.fromhex("6C6F72656D"), "lorem", "from hex to bin")
-    test:is(string.fromhex("697073756D"), "ipsum", "from hex to bin")
-    test:is(string.fromhex("6c6f72656d"), "lorem", "from hex to bin")
-    test:is(string.fromhex("697073756d"), "ipsum", "from hex to bin")
-    test:is(string.fromhex("6A6B6C6D6E6F"), "jklmno", "from hex to bin")
-    test:is(string.fromhex("6a6b6c6d6e6f"), "jklmno", "from hex to bin")
+test:test("fromhex", function(testcase)
+    testcase:plan(11)
+    testcase:is(string.fromhex("48656c6c6f"), "Hello", "from hex to bin")
+    testcase:is(string.fromhex("4c696e7578"), "Linux", "from hex to bin")
+    testcase:is(string.fromhex("6C6F72656D"), "lorem", "from hex to bin")
+    testcase:is(string.fromhex("697073756D"), "ipsum", "from hex to bin")
+    testcase:is(string.fromhex("6c6f72656d"), "lorem", "from hex to bin")
+    testcase:is(string.fromhex("697073756d"), "ipsum", "from hex to bin")
+    testcase:is(string.fromhex("6A6B6C6D6E6F"), "jklmno", "from hex to bin")
+    testcase:is(string.fromhex("6a6b6c6d6e6f"), "jklmno", "from hex to bin")
     local _, err = pcall(string.fromhex, "aaa")
-    test:ok(err and err:match("(even amount of chars expected," ..
+    testcase:ok(err and err:match("(even amount of chars expected," ..
                               " got odd amount)"))
-    local _, err = pcall(string.fromhex, "qq")
-    test:ok(err and err:match("(hex string expected, got non hex chars)"))
-    local _, err = pcall(string.fromhex, 795)
-    test:ok(err and err:match("(string expected, got number)"))
+    _, err = pcall(string.fromhex, "qq")
+    testcase:ok(err and err:match("(hex string expected, got non hex chars)"))
+    _, err = pcall(string.fromhex, 795)
+    testcase:ok(err and err:match("(string expected, got number)"))
 end)
 
-test:test("strip", function(test)
-    test:plan(45)
+test:test("strip", function(testcase)
+    testcase:plan(45)
     local str = "  Hello world! "
-    test:is(string.strip(str), "Hello world!", "strip (without chars)")
-    test:is(string.lstrip(str), "Hello world! ", "lstrip (without chars)")
-    test:is(string.rstrip(str), "  Hello world!", "rstrip (without chars)")
+    testcase:is(string.strip(str), "Hello world!", "strip (without chars)")
+    testcase:is(string.lstrip(str), "Hello world! ", "lstrip (without chars)")
+    testcase:is(string.rstrip(str), "  Hello world!", "rstrip (without chars)")
     str = ""
-    test:is(string.strip(str), str, "strip (0-len inp without chars)")
-    test:is(string.lstrip(str), str, "lstrip (0-len inp without chars)")
-    test:is(string.rstrip(str), str, "rstrip (0-len inp without chars)")
+    testcase:is(string.strip(str), str, "strip (0-len inp without chars)")
+    testcase:is(string.lstrip(str), str, "lstrip (0-len inp without chars)")
+    testcase:is(string.rstrip(str), str, "rstrip (0-len inp without chars)")
     str = " "
-    test:is(string.strip(str), "", "strip (1-len inp without chars)")
-    test:is(string.lstrip(str), "", "lstrip (1-len inp without chars)")
-    test:is(string.rstrip(str), "", "rstrip (1-len inp without chars)")
+    testcase:is(string.strip(str), "", "strip (1-len inp without chars)")
+    testcase:is(string.lstrip(str), "", "lstrip (1-len inp without chars)")
+    testcase:is(string.rstrip(str), "", "rstrip (1-len inp without chars)")
     str = "\t\v"
-    test:is(string.strip(str), "", "strip (strip everything without chars)")
-    test:is(string.lstrip(str), "", "lstrip (strip everything without chars)")
-    test:is(string.rstrip(str), "", "rstrip (strip everything without chars)")
+    testcase:is(string.strip(str), "", "strip (strip everything without chars)")
+    testcase:is(string.lstrip(str), "", "lstrip (strip everything without chars)")
+    testcase:is(string.rstrip(str), "", "rstrip (strip everything without chars)")
     str = "hello"
-    test:is(string.strip(str), str, "strip (strip nothing without chars)")
-    test:is(string.lstrip(str), str, "lstrip (strip nothing without chars)")
-    test:is(string.rstrip(str), str, "rstrip (strip nothing without chars)")
+    testcase:is(string.strip(str), str, "strip (strip nothing without chars)")
+    testcase:is(string.lstrip(str), str, "lstrip (strip nothing without chars)")
+    testcase:is(string.rstrip(str), str, "rstrip (strip nothing without chars)")
     str = " \t\n\v\f\rTEST \t\n\v\f\r"
-    test:is(string.strip(str), "TEST", "strip (all space characters without chars)")
-    test:is(string.lstrip(str), "TEST \t\n\v\f\r", "lstrip (all space characters without chars)")
-    test:is(string.rstrip(str), " \t\n\v\f\rTEST", "rstrip (all space characters without chars)")
+    testcase:is(string.strip(str), "TEST", "strip (all space characters without chars)")
+    testcase:is(string.lstrip(str), "TEST \t\n\v\f\r", "lstrip (all space characters without chars)")
+    testcase:is(string.rstrip(str), " \t\n\v\f\rTEST", "rstrip (all space characters without chars)")
 
     local chars = "#\0"
     str = "##Hello world!#"
-    test:is(string.strip(str, chars), "Hello world!", "strip (with chars)")
-    test:is(string.lstrip(str, chars), "Hello world!#", "lstrip (with chars)")
-    test:is(string.rstrip(str, chars), "##Hello world!", "rstrip (with chars)")
+    testcase:is(string.strip(str, chars), "Hello world!", "strip (with chars)")
+    testcase:is(string.lstrip(str, chars), "Hello world!#", "lstrip (with chars)")
+    testcase:is(string.rstrip(str, chars), "##Hello world!", "rstrip (with chars)")
     str = ""
-    test:is(string.strip(str, chars), str, "strip (0-len inp with chars)")
-    test:is(string.lstrip(str, chars), str, "lstrip (0-len inp with chars)")
-    test:is(string.rstrip(str, chars), str, "rstrip (0-len inp with chars)")
+    testcase:is(string.strip(str, chars), str, "strip (0-len inp with chars)")
+    testcase:is(string.lstrip(str, chars), str, "lstrip (0-len inp with chars)")
+    testcase:is(string.rstrip(str, chars), str, "rstrip (0-len inp with chars)")
     str = "#"
-    test:is(string.strip(str, chars), "", "strip (1-len inp with chars)")
-    test:is(string.lstrip(str, chars), "", "lstrip (1-len inp with chars)")
-    test:is(string.rstrip(str, chars), "", "rstrip (1-len inp with chars)")
+    testcase:is(string.strip(str, chars), "", "strip (1-len inp with chars)")
+    testcase:is(string.lstrip(str, chars), "", "lstrip (1-len inp with chars)")
+    testcase:is(string.rstrip(str, chars), "", "rstrip (1-len inp with chars)")
     str = "##"
-    test:is(string.strip(str, chars), "", "strip (strip everything with chars)")
-    test:is(string.lstrip(str, chars), "", "lstrip (strip everything with chars)")
-    test:is(string.rstrip(str, chars), "", "rstrip (strip everything with chars)")
+    testcase:is(string.strip(str, chars), "", "strip (strip everything with chars)")
+    testcase:is(string.lstrip(str, chars), "", "lstrip (strip everything with chars)")
+    testcase:is(string.rstrip(str, chars), "", "rstrip (strip everything with chars)")
     str = "hello"
-    test:is(string.strip(str, chars), str, "strip (strip nothing with chars)")
-    test:is(string.lstrip(str, chars), str, "lstrip (strip nothing with chars)")
-    test:is(string.rstrip(str, chars), str, "rstrip (strip nothing with chars)")
+    testcase:is(string.strip(str, chars), str, "strip (strip nothing with chars)")
+    testcase:is(string.lstrip(str, chars), str, "lstrip (strip nothing with chars)")
+    testcase:is(string.rstrip(str, chars), str, "rstrip (strip nothing with chars)")
     str = "\0\0\0TEST\0"
-    test:is(string.strip(str, chars), "TEST", "strip (embedded 0s with chars)")
-    test:is(string.lstrip(str, chars), "TEST\0", "lstrip (embedded 0s with chars)")
-    test:is(string.rstrip(str, chars), "\0\0\0TEST", "rstrip (embedded 0s with chars)")
+    testcase:is(string.strip(str, chars), "TEST", "strip (embedded 0s with chars)")
+    testcase:is(string.lstrip(str, chars), "TEST\0", "lstrip (embedded 0s with chars)")
+    testcase:is(string.rstrip(str, chars), "\0\0\0TEST", "rstrip (embedded 0s with chars)")
     chars = ""
-    test:is(string.strip(str, chars), str, "strip (0-len chars)")
-    test:is(string.lstrip(str, chars), str, "lstrip (0-len chars)")
-    test:is(string.rstrip(str, chars), str, "rstrip (0-len chars)")
+    testcase:is(string.strip(str, chars), str, "strip (0-len chars)")
+    testcase:is(string.lstrip(str, chars), str, "lstrip (0-len chars)")
+    testcase:is(string.rstrip(str, chars), str, "rstrip (0-len chars)")
 
     local _, err = pcall(string.strip, 12)
-    test:ok(err and err:match("#1 to '.-%.strip' %(string expected, got number%)"), "strip err 1")
+    testcase:ok(err and err:match("#1 to '.-%.strip' %(string expected, got number%)"), "strip err 1")
     _, err = pcall(string.lstrip, 12)
-    test:ok(err and err:match("#1 to '.-%.lstrip' %(string expected, got number%)"), "lstrip err 1")
+    testcase:ok(err and err:match("#1 to '.-%.lstrip' %(string expected, got number%)"), "lstrip err 1")
     _, err = pcall(string.rstrip, 12)
-    test:ok(err and err:match("#1 to '.-%.rstrip' %(string expected, got number%)"), "rstrip err 1")
+    testcase:ok(err and err:match("#1 to '.-%.rstrip' %(string expected, got number%)"), "rstrip err 1")
 
     _, err = pcall(string.strip, "foo", 12)
-    test:ok(err and err:match("#2 to '.-%.strip' %(string expected, got number%)"), "strip err 2")
+    testcase:ok(err and err:match("#2 to '.-%.strip' %(string expected, got number%)"), "strip err 2")
     _, err = pcall(string.lstrip, "foo", 12)
-    test:ok(err and err:match("#2 to '.-%.lstrip' %(string expected, got number%)"), "lstrip err 2")
+    testcase:ok(err and err:match("#2 to '.-%.lstrip' %(string expected, got number%)"), "lstrip err 2")
     _, err = pcall(string.rstrip, "foo", 12)
-    test:ok(err and err:match("#2 to '.-%.rstrip' %(string expected, got number%)"), "rstrip err 2")
+    testcase:ok(err and err:match("#2 to '.-%.rstrip' %(string expected, got number%)"), "rstrip err 2")
 end)
 
-test:test("unicode", function(test)
-    test:plan(104)
+test:test("unicode", function(testcase)
+    testcase:plan(104)
     local str = 'хеЛлоу вОрЛд ё Ё я Я э Э ъ Ъ hElLo WorLd 1234 i I İ 勺#☢༺'
     local upper_res = 'ХЕЛЛОУ ВОРЛД Ё Ё Я Я Э Э Ъ Ъ HELLO WORLD 1234 I I İ 勺#☢༺'
     local lower_res = 'хеллоу ворлд ё ё я я э э ъ ъ hello world 1234 i i i̇ 勺#☢༺'
     local s = utf8.upper(str)
-    test:is(s, upper_res, 'default locale upper')
+    testcase:is(s, upper_res, 'default locale upper')
     s = utf8.lower(str)
-    test:is(s, lower_res, 'default locale lower')
-    test:is(utf8.upper(''), '', 'empty string upper')
-    test:is(utf8.lower(''), '', 'empty string lower')
-    local err
-    s, err = pcall(utf8.upper, true)
-    test:isnt(err:find('Usage'), nil, 'upper usage is checked')
-    s, err = pcall(utf8.lower, true)
-    test:isnt(err:find('Usage'), nil, 'lower usage is checked')
-
-    test:is(utf8.isupper('a'), false, 'isupper("a")')
-    test:is(utf8.isupper('A'), true, 'isupper("A")')
-    test:is(utf8.islower('a'), true, 'islower("a")')
-    test:is(utf8.islower('A'), false, 'islower("A")')
-    test:is(utf8.isalpha('a'), true, 'isalpha("a")')
-    test:is(utf8.isalpha('A'), true, 'isalpha("A")')
-    test:is(utf8.isalpha('aa'), false, 'isalpha("aa")')
-    test:is(utf8.isalpha('勺'), true, 'isalpha("勺")')
-    test:is(utf8.isupper('Ё'), true, 'isupper("Ё")')
-    test:is(utf8.islower('ё'), true, 'islower("ё")')
-    test:is(utf8.isdigit('a'), false, 'isdigit("a")')
-    test:is(utf8.isdigit('1'), true, 'isdigit("1")')
-    test:is(utf8.isdigit('9'), true, 'isdigit("9")')
-
-    test:is(utf8.len(str), 56, 'len works on complex string')
+    testcase:is(s, lower_res, 'default locale lower')
+    testcase:is(utf8.upper(''), '', 'empty string upper')
+    testcase:is(utf8.lower(''), '', 'empty string lower')
+    local err, _
+    _, err = pcall(utf8.upper, true)
+    testcase:isnt(err:find('Usage'), nil, 'upper usage is checked')
+    _, err = pcall(utf8.lower, true)
+    testcase:isnt(err:find('Usage'), nil, 'lower usage is checked')
+
+    testcase:is(utf8.isupper('a'), false, 'isupper("a")')
+    testcase:is(utf8.isupper('A'), true, 'isupper("A")')
+    testcase:is(utf8.islower('a'), true, 'islower("a")')
+    testcase:is(utf8.islower('A'), false, 'islower("A")')
+    testcase:is(utf8.isalpha('a'), true, 'isalpha("a")')
+    testcase:is(utf8.isalpha('A'), true, 'isalpha("A")')
+    testcase:is(utf8.isalpha('aa'), false, 'isalpha("aa")')
+    testcase:is(utf8.isalpha('勺'), true, 'isalpha("勺")')
+    testcase:is(utf8.isupper('Ё'), true, 'isupper("Ё")')
+    testcase:is(utf8.islower('ё'), true, 'islower("ё")')
+    testcase:is(utf8.isdigit('a'), false, 'isdigit("a")')
+    testcase:is(utf8.isdigit('1'), true, 'isdigit("1")')
+    testcase:is(utf8.isdigit('9'), true, 'isdigit("9")')
+
+    testcase:is(utf8.len(str), 56, 'len works on complex string')
     s = '12İ☢勺34'
-    test:is(utf8.len(s), 7, 'len works no options')
-    test:is(utf8.len(s, 1), 7, 'default start is 1')
-    test:is(utf8.len(s, 2), 6, 'start 2')
-    test:is(utf8.len(s, 3), 5, 'start 3')
+    testcase:is(utf8.len(s), 7, 'len works no options')
+    testcase:is(utf8.len(s, 1), 7, 'default start is 1')
+    testcase:is(utf8.len(s, 2), 6, 'start 2')
+    testcase:is(utf8.len(s, 3), 5, 'start 3')
     local c
     c, err = utf8.len(s, 4)
-    test:isnil(c, 'middle of symbol offset is error')
-    test:is(err, 4, 'error on 4 byte')
-    test:is(utf8.len(s, 5), 4, 'start 5')
-    c, err = utf8.len(s, 6)
-    test:is(err, 6, 'error on 6 byte')
-    c, err = utf8.len(s, 0)
-    test:is(err, 'position is out of string', 'range is out of string')
-    test:is(utf8.len(s, #s), 1, 'start from the end')
-    test:is(utf8.len(s, #s + 1), 0, 'position is out of string')
-    test:is(utf8.len(s, 1, -1), 7, 'default end is -1')
-    test:is(utf8.len(s, 1, -2), 6, 'end -2')
-    test:is(utf8.len(s, 1, -3), 5, 'end -3')
-    test:is(utf8.len(s, 1, -4), 5, 'end in the middle of symbol')
-    test:is(utf8.len(s, 1, -5), 5, 'end in the middle of symbol')
-    test:is(utf8.len(s, 1, -6), 5, 'end in the middle of symbol')
-    test:is(utf8.len(s, 1, -7), 4, 'end -7')
-    test:is(utf8.len(s, 2, -7), 3, '[2, -7]')
-    test:is(utf8.len(s, 3, -7), 2, '[3, -7]')
-    c, err = utf8.len(s, 4, -7)
-    test:is(err, 4, '[4, -7] is error - start from the middle of symbol')
-    test:is(utf8.len(s, 10, -100), 0, 'it is ok to be out of str by end pos')
-    test:is(utf8.len(s, 10, -10), 0, 'it is ok to swap end and start pos')
-    test:is(utf8.len(''), 0, 'empty len')
-    test:is(utf8.len(s, -6, -1), 3, 'pass both negative offsets')
-    test:is(utf8.len(s, 3, 3), 1, "end in the middle on the same symbol as start")
-    c, err = utf8.len('a\xF4')
-    test:is(err, 2, "invalid unicode in the middle of the string")
+    testcase:isnil(c, 'middle of symbol offset is error')
+    testcase:is(err, 4, 'error on 4 byte')
+    testcase:is(utf8.len(s, 5), 4, 'start 5')
+    _, err = utf8.len(s, 6)
+    testcase:is(err, 6, 'error on 6 byte')
+    _, err = utf8.len(s, 0)
+    testcase:is(err, 'position is out of string', 'range is out of string')
+    testcase:is(utf8.len(s, #s), 1, 'start from the end')
+    testcase:is(utf8.len(s, #s + 1), 0, 'position is out of string')
+    testcase:is(utf8.len(s, 1, -1), 7, 'default end is -1')
+    testcase:is(utf8.len(s, 1, -2), 6, 'end -2')
+    testcase:is(utf8.len(s, 1, -3), 5, 'end -3')
+    testcase:is(utf8.len(s, 1, -4), 5, 'end in the middle of symbol')
+    testcase:is(utf8.len(s, 1, -5), 5, 'end in the middle of symbol')
+    testcase:is(utf8.len(s, 1, -6), 5, 'end in the middle of symbol')
+    testcase:is(utf8.len(s, 1, -7), 4, 'end -7')
+    testcase:is(utf8.len(s, 2, -7), 3, '[2, -7]')
+    testcase:is(utf8.len(s, 3, -7), 2, '[3, -7]')
+    _, err = utf8.len(s, 4, -7)
+    testcase:is(err, 4, '[4, -7] is error - start from the middle of symbol')
+    testcase:is(utf8.len(s, 10, -100), 0, 'it is ok to be out of str by end pos')
+    testcase:is(utf8.len(s, 10, -10), 0, 'it is ok to swap end and start pos')
+    testcase:is(utf8.len(''), 0, 'empty len')
+    testcase:is(utf8.len(s, -6, -1), 3, 'pass both negative offsets')
+    testcase:is(utf8.len(s, 3, 3), 1, "end in the middle on the same symbol as start")
+    _, err = utf8.len('a\xF4')
+    testcase:is(err, 2, "invalid unicode in the middle of the string")
 
     local chars = {}
     local codes = {}
@@ -278,21 +278,21 @@ test:test("unicode", function(test)
         table.insert(chars, utf8.char(code))
         table.insert(codes, code)
     end
-    test:is(table.concat(chars), s, "next and char works")
-    c, err = pcall(utf8.char, 'kek')
-    test:isnt(err:find('bad argument'), nil, 'char usage is checked')
-    c, err = pcall(utf8.next, true)
-    test:isnt(err:find('Usage'), nil, 'next usage is checked')
-    c, err = pcall(utf8.next, '1234', true)
-    test:isnt(err:find('bad argument'), nil, 'next usage is checked')
+    testcase:is(table.concat(chars), s, "next and char works")
+    _, err = pcall(utf8.char, 'kek')
+    testcase:isnt(err:find('bad argument'), nil, 'char usage is checked')
+    _, err = pcall(utf8.next, true)
+    testcase:isnt(err:find('Usage'), nil, 'next usage is checked')
+    _, err = pcall(utf8.next, '1234', true)
+    testcase:isnt(err:find('bad argument'), nil, 'next usage is checked')
     local offset
     offset, c = utf8.next('')
-    test:isnil(offset, 'next on empty - nil offset')
-    test:isnil(c, 'next on empty - nil code')
+    testcase:isnil(offset, 'next on empty - nil offset')
+    testcase:isnil(c, 'next on empty - nil code')
     offset, c = utf8.next('123', 100)
-    test:isnil(offset, 'out of string - nil offset')
-    test:isnil(c, 'out of string - nil code')
-    test:is(utf8.char(unpack(codes)), s, 'char with multiple values')
+    testcase:isnil(offset, 'out of string - nil offset')
+    testcase:isnil(c, 'out of string - nil code')
+    testcase:is(utf8.char(unpack(codes)), s, 'char with multiple values')
 
     local uppers = 0
     local lowers = 0
@@ -304,70 +304,70 @@ test:test("unicode", function(test)
         if utf8.isalpha(code) then letters = letters + 1 end
         if utf8.isdigit(code) then digits = digits + 1 end
     end
-    test:is(uppers, 13, 'uppers by code')
-    test:is(lowers, 19, 'lowers by code')
-    test:is(letters, 33, 'letters by code')
-    test:is(digits, 4, 'digits by code')
+    testcase:is(uppers, 13, 'uppers by code')
+    testcase:is(lowers, 19, 'lowers by code')
+    testcase:is(letters, 33, 'letters by code')
+    testcase:is(digits, 4, 'digits by code')
 
     s = '12345678'
-    test:is(utf8.sub(s, 1, 1), '1', 'sub [1]')
-    test:is(utf8.sub(s, 1, 2), '12', 'sub [1:2]')
-    test:is(utf8.sub(s, 2, 2), '2', 'sub [2:2]')
-    test:is(utf8.sub(s, 0, 2), '12', 'sub [0:2]')
-    test:is(utf8.sub(s, 3, 7), '34567', 'sub [3:7]')
-    test:is(utf8.sub(s, 7, 3), '', 'sub [7:3]')
-    test:is(utf8.sub(s, 3, 100), '345678', 'sub [3:100]')
-    test:is(utf8.sub(s, 100, 3), '', 'sub [100:3]')
-
-    test:is(utf8.sub(s, 5), '5678', 'sub [5:]')
-    test:is(utf8.sub(s, 1, -1), s, 'sub [1:-1]')
-    test:is(utf8.sub(s, 1, -2), '1234567', 'sub [1:-2]')
-    test:is(utf8.sub(s, 2, -2), '234567', 'sub [2:-2]')
-    test:is(utf8.sub(s, 3, -3), '3456', 'sub [3:-3]')
-    test:is(utf8.sub(s, 5, -4), '5', 'sub [5:-4]')
-    test:is(utf8.sub(s, 7, -7), '', 'sub[7:-7]')
-
-    test:is(utf8.sub(s, -2, -1), '78', 'sub [-2:-1]')
-    test:is(utf8.sub(s, -1, -1), '8', 'sub [-1:-1]')
-    test:is(utf8.sub(s, -4, -2), '567', 'sub [-4:-2]')
-    test:is(utf8.sub(s, -400, -2), '1234567', 'sub [-400:-2]')
-    test:is(utf8.sub(s, -3, -5), '', 'sub [-3:-5]')
-
-    test:is(utf8.sub(s, -6, 5), '345', 'sub [-6:5]')
-    test:is(utf8.sub(s, -5, 4), '4', 'sub [-5:4]')
-    test:is(utf8.sub(s, -2, 2), '', 'sub [-2:2]')
-    test:is(utf8.sub(s, -1, 8), '8', 'sub [-1:8]')
-
-    c, err = pcall(utf8.sub)
-    test:isnt(err:find('Usage'), nil, 'usage is checked')
-    c, err = pcall(utf8.sub, true)
-    test:isnt(err:find('Usage'), nil, 'usage is checked')
-    c, err = pcall(utf8.sub, '123')
-    test:isnt(err:find('Usage'), nil, 'usage is checked')
-    c, err = pcall(utf8.sub, '123', true)
-    test:isnt(err:find('bad argument'), nil, 'usage is checked')
-    c, err = pcall(utf8.sub, '123', 1, true)
-    test:isnt(err:find('bad argument'), nil, 'usage is checked')
+    testcase:is(utf8.sub(s, 1, 1), '1', 'sub [1]')
+    testcase:is(utf8.sub(s, 1, 2), '12', 'sub [1:2]')
+    testcase:is(utf8.sub(s, 2, 2), '2', 'sub [2:2]')
+    testcase:is(utf8.sub(s, 0, 2), '12', 'sub [0:2]')
+    testcase:is(utf8.sub(s, 3, 7), '34567', 'sub [3:7]')
+    testcase:is(utf8.sub(s, 7, 3), '', 'sub [7:3]')
+    testcase:is(utf8.sub(s, 3, 100), '345678', 'sub [3:100]')
+    testcase:is(utf8.sub(s, 100, 3), '', 'sub [100:3]')
+
+    testcase:is(utf8.sub(s, 5), '5678', 'sub [5:]')
+    testcase:is(utf8.sub(s, 1, -1), s, 'sub [1:-1]')
+    testcase:is(utf8.sub(s, 1, -2), '1234567', 'sub [1:-2]')
+    testcase:is(utf8.sub(s, 2, -2), '234567', 'sub [2:-2]')
+    testcase:is(utf8.sub(s, 3, -3), '3456', 'sub [3:-3]')
+    testcase:is(utf8.sub(s, 5, -4), '5', 'sub [5:-4]')
+    testcase:is(utf8.sub(s, 7, -7), '', 'sub[7:-7]')
+
+    testcase:is(utf8.sub(s, -2, -1), '78', 'sub [-2:-1]')
+    testcase:is(utf8.sub(s, -1, -1), '8', 'sub [-1:-1]')
+    testcase:is(utf8.sub(s, -4, -2), '567', 'sub [-4:-2]')
+    testcase:is(utf8.sub(s, -400, -2), '1234567', 'sub [-400:-2]')
+    testcase:is(utf8.sub(s, -3, -5), '', 'sub [-3:-5]')
+
+    testcase:is(utf8.sub(s, -6, 5), '345', 'sub [-6:5]')
+    testcase:is(utf8.sub(s, -5, 4), '4', 'sub [-5:4]')
+    testcase:is(utf8.sub(s, -2, 2), '', 'sub [-2:2]')
+    testcase:is(utf8.sub(s, -1, 8), '8', 'sub [-1:8]')
+
+    _, err = pcall(utf8.sub)
+    testcase:isnt(err:find('Usage'), nil, 'usage is checked')
+    _, err = pcall(utf8.sub, true)
+    testcase:isnt(err:find('Usage'), nil, 'usage is checked')
+    _, err = pcall(utf8.sub, '123')
+    testcase:isnt(err:find('Usage'), nil, 'usage is checked')
+    _, err = pcall(utf8.sub, '123', true)
+    testcase:isnt(err:find('bad argument'), nil, 'usage is checked')
+    _, err = pcall(utf8.sub, '123', 1, true)
+    testcase:isnt(err:find('bad argument'), nil, 'usage is checked')
 
     local s1 = '☢'
     local s2 = 'İ'
-    test:is(s1 < s2, false, 'test binary cmp')
-    test:is(utf8.cmp(s1, s2) < 0, true, 'test unicode <')
-    test:is(utf8.cmp(s1, s1) == 0, true, 'test unicode eq')
-    test:is(utf8.cmp(s2, s1) > 0, true, 'test unicode >')
-    test:is(utf8.casecmp('a', 'A') == 0, true, 'test icase ==')
-    test:is(utf8.casecmp('b', 'A') > 0, true, 'test icase >, first')
-    test:is(utf8.casecmp('B', 'a') > 0, true, 'test icase >, second >')
-    test:is(utf8.cmp('', '') == 0, true, 'test empty compare')
-    test:is(utf8.cmp('', 'a') < 0, true, 'test left empty compare')
-    test:is(utf8.cmp('a', '') > 0, true, 'test right empty compare')
-    test:is(utf8.casecmp('', '') == 0, true, 'test empty icompare')
-    test:is(utf8.casecmp('', 'a') < 0, true, 'test left empty icompare')
-    test:is(utf8.casecmp('a', '') > 0, true, 'test right empty icompare')
+    testcase:is(s1 < s2, false, 'test binary cmp')
+    testcase:is(utf8.cmp(s1, s2) < 0, true, 'test unicode <')
+    testcase:is(utf8.cmp(s1, s1) == 0, true, 'test unicode eq')
+    testcase:is(utf8.cmp(s2, s1) > 0, true, 'test unicode >')
+    testcase:is(utf8.casecmp('a', 'A') == 0, true, 'test icase ==')
+    testcase:is(utf8.casecmp('b', 'A') > 0, true, 'test icase >, first')
+    testcase:is(utf8.casecmp('B', 'a') > 0, true, 'test icase >, second >')
+    testcase:is(utf8.cmp('', '') == 0, true, 'test empty compare')
+    testcase:is(utf8.cmp('', 'a') < 0, true, 'test left empty compare')
+    testcase:is(utf8.cmp('a', '') > 0, true, 'test right empty compare')
+    testcase:is(utf8.casecmp('', '') == 0, true, 'test empty icompare')
+    testcase:is(utf8.casecmp('', 'a') < 0, true, 'test left empty icompare')
+    testcase:is(utf8.casecmp('a', '') > 0, true, 'test right empty icompare')
 
     -- gh-3709: utf8 can not handle an empty string.
-    test:is(utf8.lower(''), '', 'lower empty')
-    test:is(utf8.upper(''), '', 'upper empty')
+    testcase:is(utf8.lower(''), '', 'lower empty')
+    testcase:is(utf8.upper(''), '', 'upper empty')
 end)
 
 os.exit(test:check() == true and 0 or -1)
diff --git a/test/app-tap/tap.test.lua b/test/app-tap/tap.test.lua
index e2a78f630..0a8d8c6a1 100755
--- a/test/app-tap/tap.test.lua
+++ b/test/app-tap/tap.test.lua
@@ -11,7 +11,7 @@ local tap = require "tap"
 --
 -- Create a root test
 --
-test = tap.test("root test")
+local test = tap.test("root test")
 -- Disable stack traces for this test because Tarantool test system also
 -- checks test output.
 test.trace = false
@@ -88,7 +88,7 @@ end)
 --
 -- Subtest without callbacks.
 --
-sub2 = test:test("subtest 2")
+local sub2 = test:test("subtest 2")
     sub2:plan(1)
     sub2:ok(true, 'true in subtest')
     sub2:diag('hello from subtest')
@@ -97,17 +97,17 @@ sub2 = test:test("subtest 2")
 --
 -- Multisubtest
 --
-test:test("1 level", function(t)
-    t:plan(1)
-    t:test("2 level", function(t)
-        t:plan(1)
-        t:test("3 level", function(t)
-            t:plan(1)
-            t:test("4 level", function(t)
-                t:plan(1)
-                t:test("5 level", function(t)
-                    t:plan(1)
-                    t:ok(true, 'ok')
+test:test("1 level", function(t1)
+    t1:plan(1)
+    t1:test("2 level", function(t2)
+        t2:plan(1)
+        t2:test("3 level", function(t3)
+            t3:plan(1)
+            t3:test("4 level", function(t4)
+                t4:plan(1)
+                t4:test("5 level", function(t5)
+                    t5:plan(1)
+                    t5:ok(true, 'ok')
                 end)
             end)
         end)
diff --git a/test/app-tap/tarantoolctl.test.lua b/test/app-tap/tarantoolctl.test.lua
index 4d7059559..5797b4e6b 100755
--- a/test/app-tap/tarantoolctl.test.lua
+++ b/test/app-tap/tarantoolctl.test.lua
@@ -4,7 +4,6 @@ local ffi      = require('ffi')
 local fio      = require('fio')
 local tap      = require('tap')
 local uuid     = require('uuid')
-local yaml     = require('yaml')
 local errno    = require('errno')
 local fiber    = require('fiber')
 local ok, test_run = pcall(require, 'test_run')
@@ -33,7 +32,7 @@ local function recursive_rmdir(path)
         end
     end
     if fio.rmdir(path) == false then
-        print(string.format('!!! failed to rmdir path "%s"', file))
+        print(string.format('!!! failed to rmdir path "%s"', path))
         print(string.format('!!! [errno %s]: %s', errno(), errno.strerror()))
     end
 end
@@ -51,7 +50,7 @@ int execvp(const char *file, char *const argv[]);
 ]]
 
 -- background checks
-tctlcfg_code = [[default_cfg = {
+local tctlcfg_code = [[default_cfg = {
     pid_file  = '.', wal_dir = '.', memtx_dir   = '.' ,
     vinyl_dir = '.', log  = '.', background = true,
 }
@@ -97,23 +96,14 @@ local function tctl_wait_start(dir, name)
             fiber.sleep(0.01)
         end
         ::again::
-        while true do
-            local stat, nb = pcall(require('net.box').new, path, {
-                wait_connected = true, console = true
-            })
-            if stat == false then
-                fiber.sleep(0.01)
-                goto again
-            else
-                break
-            end
-            local stat, msg = pcall(nb.eval, nb, 'require("fiber").time()')
-            if stat == false then
-                fiber.sleep(0.01)
-            else
-                break
-            end
+        local stat, _ = pcall(require('net.box').new, path, {
+            wait_connected = true, console = true
+        })
+        if stat == false then
+            fiber.sleep(0.01)
+            goto again
         end
+        return
     end
 end
 
@@ -124,8 +114,7 @@ local function tctl_wait_stop(dir, name)
     end
 end
 
-local function tctl_command(dir, cmd, args, name)
-    local pid = nil
+local function tctl_command(dir, cmd, args)
     if not fio.stat(fio.pathjoin(dir, '.tarantoolctl')) then
         create_script(dir, '.tarantoolctl', tctlcfg_code)
     end
@@ -224,7 +213,7 @@ do
     -- bad code
     local code = [[ box.cfg{ ]]
     create_script(dir, 'bad_script.lua',  code)
-    local code = [[ box.cfg{memtx_memory = 104857600} ]]
+    code = [[ box.cfg{memtx_memory = 104857600} ]]
     create_script(dir, 'good_script.lua', code)
 
     local status, err = pcall(function()
@@ -258,9 +247,9 @@ do
     -- bad code
     local code = [[ error('help'); return 1]]
     create_script(dir, 'bad_script.lua',  code)
-    local code = [[ return 1]]
+    code = [[ return 1]]
     create_script(dir, 'ok_script.lua',  code)
-    local code = [[ box.cfg{memtx_memory = 104857600} box.once('help', function() end)]]
+    code = [[ box.cfg{memtx_memory = 104857600} box.once('help', function() end)]]
     create_script(dir, 'good_script.lua', code)
 
     local status, err = pcall(function()
@@ -327,12 +316,12 @@ end
 do
     local dir = fio.tempdir()
 
-    local function test_help(test, dir, cmd, e_stderr)
-        local desc = dir and 'with config' or 'without config'
-        dir = dir or './'
-        local res, stdout, stderr = run_command(dir, cmd)
+    local function test_help(testcase, directory, cmd, e_stderr)
+        local desc = directory and 'with config' or 'without config'
+        directory = directory or './'
+        local _, _, stderr = run_command(directory, cmd)
         if e_stderr ~= nil then
-            if not test:ok(stderr:find(e_stderr), ("check stderr of '%s' %s"):format(cmd, desc)) then
+            if not testcase:ok(stderr:find(e_stderr), ("check stderr of '%s' %s"):format(cmd, desc)) then
                 print(("Expected to find '%s' in '%s'"):format(e_stderr, stderr))
             end
         end
@@ -381,22 +370,22 @@ do
 
     create_script(dir, 'filler.lua', filler_code)
 
-    local function check_ctlcat_xlog(test, dir, args, delim, lc)
+    local function check_ctlcat_xlog(testcase, directory, args, delim, lc)
         local command_base = 'tarantoolctl cat filler/00000000000000000000.xlog'
         local desc = args and "cat + " .. args or "cat"
         args = args and " " .. args or ""
-        local res, stdout, stderr = run_command(dir, command_base .. args)
-        test:is(res, 0, desc .. " result")
-        test:is(select(2, stdout:gsub(delim, delim)), lc, desc .. " line count")
+        local res, stdout, _ = run_command(directory, command_base .. args)
+        testcase:is(res, 0, desc .. " result")
+        testcase:is(select(2, stdout:gsub(delim, delim)), lc, desc .. " line count")
     end
 
-    local function check_ctlcat_snap(test, dir, args, delim, lc)
+    local function check_ctlcat_snap(testcase, directory, args, delim, lc)
         local command_base = 'tarantoolctl cat filler/00000000000000000000.snap'
         local desc = args and "cat + " .. args or "cat"
         args = args and " " .. args or ""
-        local res, stdout, stderr = run_command(dir, command_base .. args)
-        test:is(res, 0, desc .. " result")
-        test:is(select(2, stdout:gsub(delim, delim)), lc, desc .. " line count")
+        local res, stdout, _ = run_command(directory, command_base .. args)
+        testcase:is(res, 0, desc .. " result")
+        testcase:is(select(2, stdout:gsub(delim, delim)), lc, desc .. " line count")
     end
 
     local status, err = pcall(function()
@@ -413,7 +402,8 @@ do
             check_ctlcat_xlog(test_i, dir, "--from=3 --to=6 --format=json --show-system", "\n", 3)
             check_ctlcat_xlog(test_i, dir, "--from=6 --to=3 --format=json --show-system", "\n", 0)
             check_ctlcat_xlog(test_i, dir, "--from=3 --to=6 --format=json --show-system --replica 1", "\n", 3)
-            check_ctlcat_xlog(test_i, dir, "--from=3 --to=6 --format=json --show-system --replica 1 --replica 2", "\n", 3)
+            check_ctlcat_xlog(test_i, dir,
+		"--from=3 --to=6 --format=json --show-system --replica 1 --replica 2", "\n", 3)
             check_ctlcat_xlog(test_i, dir, "--from=3 --to=6 --format=json --show-system --replica 2", "\n", 0)
             check_ctlcat_snap(test_i, dir, "--space=280", "---\n", 25)
             check_ctlcat_snap(test_i, dir, "--space=288", "---\n", 53)
@@ -478,10 +468,10 @@ else
             check_ok(test_i, dir, 'start', 'filler', 0)
             local lsn_before = test_run:get_lsn("remote", 1)
             test_i:is(lsn_before, 4, "check lsn before")
-            local res, stdout, stderr = run_command(dir, command_base)
+            local res, _, _ = run_command(dir, command_base)
             test_i:is(res, 0, "execution result")
             test_i:is(test_run:get_lsn("remote", 1), 10, "check lsn after")
-            local res, stdout, stderr = run_command(dir, command_base)
+            res, _, _ = run_command(dir, command_base)
             test_i:is(res, 0, "execution result")
             test_i:is(test_run:get_lsn("remote", 1), 16, "check lsn after")
         end)
@@ -497,7 +487,7 @@ else
     end
 end
 
-test:test('filter_xlog', function(test)
+test:test('filter_xlog', function(testcase)
     local xlog_data = {
         -- [1] =
         {
@@ -615,13 +605,13 @@ test:test('filter_xlog', function(test)
             exp_result = {x[7], x[9]},
         },
     }
-    test:plan(#cases)
+    testcase:plan(#cases)
 
     rawset(_G, 'TARANTOOLCTL_UNIT_TEST', true)
     local tarantoolctl = dofile(TARANTOOLCTL_PATH)
 
     -- Like xlog.pairs().
-    local function gen(param, lsn)
+    local function gen(param)
         local row = param.data[param.idx]
         if row == nil then
             return
@@ -635,14 +625,14 @@ test:test('filter_xlog', function(test)
     end
 
     for _, case in ipairs(cases) do
-        local gen, param, state = xlog_data_pairs(xlog_data)
+        local data_pairs, param, state = xlog_data_pairs(xlog_data)
         local res = {}
-        tarantoolctl.internal.filter_xlog(gen, param, state, case.opts,
+        tarantoolctl.internal.filter_xlog(data_pairs, param, state, case.opts,
             function(record)
                 table.insert(res, record)
             end
         )
-        test:is_deeply(res, case.exp_result, case[1])
+        testcase:is_deeply(res, case.exp_result, case[1])
     end
 end)
 
diff --git a/test/app-tap/trigger.test.lua b/test/app-tap/trigger.test.lua
index a31d45e5f..ea23b3325 100755
--- a/test/app-tap/trigger.test.lua
+++ b/test/app-tap/trigger.test.lua
@@ -14,8 +14,8 @@ test:plan(3)
 local trigger_list = trigger.new("sweet trigger")
 test:ok(trigger_list ~= nil, "test that trigger list is created")
 
-test:test("simple trigger test", function(test)
-    test:plan(10)
+test:test("simple trigger test", function(testcase)
+    testcase:plan(10)
 
     local cnt = 0
     local function trigger_cnt() cnt = cnt + 1 end
@@ -23,35 +23,35 @@ test:test("simple trigger test", function(test)
     -- Append first trigger
     trigger_list(trigger_cnt)
     trigger_list:run()
-    test:is(cnt, 1, "check first run")
+    testcase:is(cnt, 1, "check first run")
     -- Append second trigger
     trigger_list(trigger_cnt)
     trigger_list:run()
-    test:is(cnt, 3, "check first run")
+    testcase:is(cnt, 3, "check first run")
     -- Check listing
     local list_copy = trigger_list()
-    test:is(#list_copy, 2, "trigger() count")
+    testcase:is(#list_copy, 2, "trigger() count")
     table.remove(list_copy)
-    test:is(#trigger_list(), 2, "check that we've returned copy")
+    testcase:is(#trigger_list(), 2, "check that we've returned copy")
 
     -- Delete both triggers
-    test:is(trigger_list(nil, trigger_cnt), trigger_cnt, "pop trigger")
+    testcase:is(trigger_list(nil, trigger_cnt), trigger_cnt, "pop trigger")
     trigger_list:run()
-    test:is(#trigger_list(), 1, "check trigger count after delete")
-    test:is(cnt, 4, "check third run")
-    test:is(trigger_list(nil, trigger_cnt), trigger_cnt, "pop trigger")
+    testcase:is(#trigger_list(), 1, "check trigger count after delete")
+    testcase:is(cnt, 4, "check third run")
+    testcase:is(trigger_list(nil, trigger_cnt), trigger_cnt, "pop trigger")
     trigger_list:run()
-    test:is(#trigger_list(), 0, "check trigger count after delete")
+    testcase:is(#trigger_list(), 0, "check trigger count after delete")
 
 
     -- Check that we've failed to delete trigger
-    local stat, err = pcall(getmetatable(trigger_list).__call, trigger_list,
+    local _, err = pcall(getmetatable(trigger_list).__call, trigger_list,
                             nil, trigger_cnt)
-    test:ok(string.find(err, "is not found"), "check error")
+    testcase:ok(string.find(err, "is not found"), "check error")
 end)
 
-test:test("errored trigger test", function(test)
-    test:plan(6)
+test:test("errored trigger test", function(testcase)
+    testcase:plan(6)
 
     --
     -- Check that trigger:run() fails on the first error
@@ -61,27 +61,27 @@ test:test("errored trigger test", function(test)
     local function trigger_cnt() cnt = cnt + 1 end
     local function trigger_errored() error("test error") end
 
-    test:is(#trigger_list(), 0, "check for empty triggers")
+    testcase:is(#trigger_list(), 0, "check for empty triggers")
 
     -- Append first trigger
     trigger_list(trigger_cnt)
     trigger_list:run()
-    test:is(cnt, 1, "check simple trigger")
+    testcase:is(cnt, 1, "check simple trigger")
     -- Append errored trigger
     trigger_list(trigger_errored)
-    local status = pcall(function() trigger_list:run() end)
-    test:is(cnt, 2, "check simple+error trigger")
+    pcall(function() trigger_list:run() end)
+    testcase:is(cnt, 2, "check simple+error trigger")
     -- Flush triggers
     table_clear(trigger_list)
-    test:is(#trigger_list(), 0, "successfull flush")
+    testcase:is(#trigger_list(), 0, "successfull flush")
     -- Append first trigger
     trigger_list(trigger_errored)
-    local status = pcall(function() trigger_list:run() end)
-    test:is(cnt, 2, "check error trigger")
+    pcall(function() trigger_list:run() end)
+    testcase:is(cnt, 2, "check error trigger")
     -- Append errored trigger
     trigger_list(trigger_cnt)
-    local status = pcall(function() trigger_list:run() end)
-    test:is(cnt, 2, "check error+simple trigger")
+    pcall(function() trigger_list:run() end)
+    testcase:is(cnt, 2, "check error+simple trigger")
 end)
 
 os.exit(test:check() == true and 0 or -1)
diff --git a/test/app-tap/yaml.test.lua b/test/app-tap/yaml.test.lua
index 4669b6102..82fcb90c0 100755
--- a/test/app-tap/yaml.test.lua
+++ b/test/app-tap/yaml.test.lua
@@ -37,8 +37,6 @@ local function test_compact(test, s)
         "---\n- {'k': 'v'}\n...\n", "flow map")
     test:is(getmetatable(ss.decode(ss.encode({k = 'v'}))).__serialize, "map",
         "decoded __serialize is map")
-
-    ss = nil
 end
 
 local function test_output(test, s)
@@ -83,11 +81,11 @@ local function test_tagged(test, s)
     -- Test encoding tags.
     --
     local prefix = 'tag:tarantool.io/push,2018'
-    local ok, err = pcall(s.encode, 200, {tag_handle = true, tag_prefix = 100})
+    local _, err = pcall(s.encode, 200, {tag_handle = true, tag_prefix = 100})
     test:isnt(err:find('Usage'), nil, "encode usage")
-    ok, err = pcall(s.encode, 100, {tag_handle = 'handle'})
+    _, err = pcall(s.encode, 100, {tag_handle = 'handle'})
     test:isnt(err:find('Usage'), nil, "encode usage, no prefix")
-    ok, err = pcall(s.encode, 100, {tag_prefix = 'prefix'})
+    _, err = pcall(s.encode, 100, {tag_prefix = 'prefix'})
     test:isnt(err:find('Usage'), nil, "encode usage, no handle")
     local ret
     ret, err = s.encode(300, {tag_handle = '!push', tag_prefix = prefix})
@@ -100,11 +98,12 @@ local function test_tagged(test, s)
     --
     -- Test decoding tags.
     --
-    ok, err = pcall(s.decode)
+    _, err = pcall(s.decode)
     test:isnt(err:find('Usage'), nil, "decode usage")
-    ok, err = pcall(s.decode, false)
+    _, err = pcall(s.decode, false)
     test:isnt(err:find('Usage'), nil, "decode usage")
-    local handle, prefix = s.decode(ret, {tag_only = true})
+    local handle
+    handle, prefix = s.decode(ret, {tag_only = true})
     test:is(handle, "!print!", "handle is decoded ok")
     test:is(prefix, "tag:tarantool.io/push,2018", "prefix is decoded ok")
     local several_tags =
@@ -114,6 +113,7 @@ local function test_tagged(test, s)
 - 100
 ...
 ]]
+    local ok
     ok, err = s.decode(several_tags, {tag_only = true})
     test:is(ok, nil, "can not decode multiple tags")
     test:is(err, "can not decode multiple tags", "same")
-- 
2.23.0



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