[Tarantool-patches] [PATCH 3/3] tap: is_deeply ignores __pairs metamethod

[olegrok@tarantool.org]

From: Oleg Babin <babinoleg@mail.ru>

After 1d85144a9b4bbbb026402848efde1ab98bf72633
is_deeply could use __pairs metamethod when
iterated through tables. It led to situation
when two similar tables could be considered
as different.
To eliminate such situation default pairs
was replaced with "pure" pairs that ignores
__pairs metamethod

Follow-up #4770, #4560
---
 src/lua/tap.lua           |  9 ++++++---
 test/app-tap/tap.result   |  6 ++++--
 test/app-tap/tap.test.lua | 24 +++++++++++++++++++++++-
 3 files changed, 33 insertions(+), 6 deletions(-)

diff --git a/src/lua/tap.lua b/src/lua/tap.lua
index 94b080d5a..23ca79f0b 100644
--- a/src/lua/tap.lua
+++ b/src/lua/tap.lua
@@ -77,7 +77,10 @@ local function skip(test, message, extra)
 end
 
 
-local nan = 0/0
+-- This pairs implementation doesn't trigger __pairs metamethod
+local function internal_pairs(tbl)
+    return next, tbl, nil
+end
 
 local function cmpdeeply(got, expected, extra)
     if type(expected) == "number" or type(got) == "number" then
@@ -107,7 +110,7 @@ local function cmpdeeply(got, expected, extra)
     local path = extra.path or '/'
     local visited_keys = {}
 
-    for i, v in pairs(got) do
+    for i, v in internal_pairs(got) do
         visited_keys[i] = true
         extra.path = path .. '/' .. i
         if not cmpdeeply(v, expected[i], extra) then
@@ -116,7 +119,7 @@ local function cmpdeeply(got, expected, extra)
     end
 
     -- check if expected contains more keys then got
-    for i, v in pairs(expected) do
+    for i, v in internal_pairs(expected) do
         if visited_keys[i] ~= true and (extra.strict or v ~= box.NULL) then
             extra.expected = 'key ' .. tostring(i)
             extra.got = 'nil'
diff --git a/test/app-tap/tap.result b/test/app-tap/tap.result
index 12bf86ec2..ecfdf11d1 100644
--- a/test/app-tap/tap.result
+++ b/test/app-tap/tap.result
@@ -137,7 +137,7 @@ not ok - failed subtests
   failed: 1
   ...
     # is_deeply
-    1..20
+    1..22
     ok - 1 and 1
     ok - abc and abc
     ok - empty tables
@@ -203,10 +203,12 @@ not ok - failed subtests
       strict: true
       ...
     ok - {a = box.NULL} and {a = box.NULL} strict true
+    ok - is_deeply ignores __pairs metamethod
+    ok - is_deeply ignores __pairs metamethod
     # is_deeply: end
 not ok - failed subtests
   ---
-  planned: 20
+  planned: 22
   failed: 8
   ...
     # like
diff --git a/test/app-tap/tap.test.lua b/test/app-tap/tap.test.lua
index e2a78f630..757781636 100755
--- a/test/app-tap/tap.test.lua
+++ b/test/app-tap/tap.test.lua
@@ -131,7 +131,7 @@ end)
 
 
 test:test('is_deeply', function(t)
-    t:plan(20)
+    t:plan(22)
 
     t:is_deeply(1, 1, '1 and 1')
     t:is_deeply('abc', 'abc', 'abc and abc')
@@ -166,6 +166,28 @@ test:test('is_deeply', function(t)
     t:is_deeply({a = box.NULL}, {a = box.NULL},
                 '{a = box.NULL} and {a = box.NULL} strict true')
     t.strict = false
+
+    --
+    -- gh-4770: is_deeply uses __pairs for iteration through the table.
+    --
+    local original = { a = 1, b = 2 }
+
+    local function custom_pairs(self)
+        local function step(tbl, k)
+            local k, v = next(tbl, k)
+            if v ~= nil then
+                v = v + 1
+            end
+            return k, v
+        end
+        return step, self, nil
+    end
+
+    setmetatable(original, {__pairs = custom_pairs })
+    t:is_deeply(original, {a = 1, b = 2},
+            'is_deeply ignores __pairs metamethod')
+    t:is_deeply({a = 1, b = 2}, original,
+            'is_deeply ignores __pairs metamethod')
 end)
 
 
-- 
2.23.0