Hi, Igor!
LGTM, except for a few nits below.
 
 
> 
>>Unfortunately, <utils.selfrun> is too complex to be maintained, so the
>>corresponding tests are split into two files: the test itself and the
>>script to be run by the test. As a result of the patch <utils.makecmd>
>>helper is introduced: it inherits some approaches from <utils.selfrun>,
>>but it's considered for more general use.
>>
>>Relates to tarantool/tarantool#8252
>>
>>Signed-off-by: Igor Munkin < imun@tarantool.org >
>>---
>> .../gh-4427-ffi-sandwich.test.lua | 69 ++++++++-----------
>> .../gh-4427-ffi-sandwich/script.lua | 25 +++++++
>> .../lj-351-print-tostring-number.test.lua | 34 +++------
>> .../lj-351-print-tostring-number/script.lua | 9 +++
>> .../lj-586-debug-non-string-error.test.lua | 2 +-
>> .../lj-flush-on-trace.test.lua | 68 ++++++++----------
>> .../lj-flush-on-trace/script.lua | 23 +++++++
>> test/tarantool-tests/utils.lua | 66 +++++-------------
>> 8 files changed, 148 insertions(+), 148 deletions(-)
>> create mode 100644 test/tarantool-tests/gh-4427-ffi-sandwich/script.lua
>> create mode 100644 test/tarantool-tests/lj-351-print-tostring-number/script.lua
>> create mode 100644 test/tarantool-tests/lj-flush-on-trace/script.lua
>>
>>diff --git a/test/tarantool-tests/gh-4427-ffi-sandwich.test.lua b/test/tarantool-tests/gh-4427-ffi-sandwich.test.lua
>>index dd02130c..f4795db0 100644
>>--- a/test/tarantool-tests/gh-4427-ffi-sandwich.test.lua
>>+++ b/test/tarantool-tests/gh-4427-ffi-sandwich.test.lua
>>@@ -3,52 +3,43 @@ local utils = require('utils')
><snipped>
>>+ -- TODO: Leave another toxic comment regarding SIP on macOS.
>That comment is unnecessary. Here and below.
> 
><snipped>
>>
>>diff --git a/test/tarantool-tests/utils.lua b/test/tarantool-tests/utils.lua
>>index eb11d40d..41a7c22a 100644
>>--- a/test/tarantool-tests/utils.lua
>>+++ b/test/tarantool-tests/utils.lua
>>@@ -1,7 +1,6 @@
>> local M = {}
>> 
>> local ffi = require('ffi')
>>-local tap = require('tap')
>> local bc = require('jit.bc')
>> local bit = require('bit')
>> 
>>@@ -44,55 +43,28 @@ function M.luacmd(args)
>>   return table.concat(args, ' ', idx + 1, -1)
>> end
>> 
>>-local function unshiftenv(variable, value, sep)
>>- local envvar = os.getenv(variable)
>>- return ('%s="%s%s"'):format(variable, value,
>>- envvar and ('%s%s'):format(sep, envvar) or '')
>>+local function makeenv(tabenv)
>>+ if tabenv == nil then return '' end
>>+ local flatenv = {}
>>+ for var, value in pairs(tabenv) do
>>+ table.insert(flatenv, ('%s=%s'):format(var, value))
>>+ end
>>+ return table.concat(flatenv, ' ')
>> end
>> 
>>-function M.selfrun(arg, checks)
>>- -- If TEST_SELFRUN is set, it means the test has been run via
>>- -- <io.popen>, so just return from this routine and proceed
>>- -- the execution to the test payload, ...
>>- if os.getenv('TEST_SELFRUN') then return end
>>-
>>- -- ... otherwise initialize <tap>, setup testing environment
>>- -- and run this chunk via <io.popen> for each case in <checks>.
>>- -- XXX: The function doesn't return back from this moment. It
>>- -- checks whether all assertions are fine and exits.
>>-
>>- local test = tap.test(arg[0]:match('/?(.+)%.test%.lua'))
>>-
>>- test:plan(#checks)
>>-
>>- local libext = package.cpath:match('?.(%a+);')
>>- local vars = {
>>+function M.makecmd(arg, opts)
>>+ return setmetatable({
>>     LUABIN = M.luacmd(arg),
>>- SCRIPT = arg[0],
>>- PATH = arg[0]:gsub('%.test%.lua', ''),
>>- SUFFIX = libext,
>>- ENV = table.concat({
>>- unshiftenv('LUA_PATH', '<PATH>/?.lua', ';'),
>>- unshiftenv('LUA_CPATH', '<PATH>/?.<SUFFIX>', ';'),
>>- unshiftenv((libext == 'dylib' and 'DYLD' or 'LD') .. '_LIBRARY_PATH',
>>- '<PATH>', ':'),
>>- 'TEST_SELFRUN=1',
>>- }, ' '),
>>- }
>>-
>>- local cmd = string.gsub('<ENV> <LUABIN> 2>&1 <SCRIPT>', '%<(%w+)>', vars)
>>-
>>- for _, ch in pairs(checks) do
>>- local testf = test[ch.test]
>>- assert(testf, ("tap doesn't provide test.%s function"):format(ch.test))
>>- local proc = io.popen((cmd .. (' %s'):rep(#ch.arg)):format(unpack(ch.arg)))
>>- local res = proc:read('*all'):gsub('^%s+', ''):gsub('%s+$', '')
>>- -- XXX: explicitly pass <test> as an argument to <testf>
>>- -- to emulate test:is(...), test:like(...), etc.
>>- testf(test, res, ch.res, ch.msg)
>>- end
>>-
>>- os.exit(test:check() and 0 or 1)
>>+ SCRIPT = opts and opts.script or arg[0]:gsub('%.test%.lua$', '/script.lua'),
>>+ ENV = opts and makeenv(opts.env) or '',
>>+ REDIRECT = opts and opts.redirect or '',
>>+ }, {
>>+ __call = function(self, ...)
>>+ local cmd = ('<ENV> <LUABIN> <REDIRECT> <SCRIPT>'):gsub('%<(%w+)>', self)
>>+ .. (' %s'):rep(select('#', ...)):format(...)
>>+ return io.popen(cmd):read('*all'):gsub('^%s+', ''):gsub('%s+$', '')
>>+ end
>>+ })
>That part is barely readable, so I think you should either drop
>a comment with explanation, or rewrite it in a more readable way.
>> end
>> 
>> function M.skipcond(condition, message)
>>--
>>2.30.2
>--
>Best regards,
>Maxim Kokryashkin
>