#763: Test/More.pir's is_deeply() needs work with hash corner cases
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Reporter: Infinoid | Owner:
Type: bug | Status: new
Priority: normal | Milestone:
Component: none | Version: 1.2.0
Severity: medium | Keywords:
Lang: | Patch:
Platform: |
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is_deeply() seems to compare simple hashes just fine.
However, I have some concerns; I can see a couple of things that need to
be fixed up.
Issue 1: is_deeply() can't handle hashes containing Undef values, at all.
It crashes when you try. I'm attaching a patch which adds a test for
that, but currently it crashes.
Issue 2: Once is_deeply() can handle Undefs, it will have some corner
cases to work out, with regards to undef values and nonexistent keys. I'm
not really sure what the right thing to do is, here. Say one hash is
declared with:
{{{
%hash1 = (
key1 => 1,
key2 => 2,
key3 => undef,
);
}}}
And the other was declared with:
{{{
%hash2 = (
key1 => 1,
key2 => 2,
);
}}}
Should they compare equal? Does %hash2{key3} return an Undef PMC, or
PMCNULL?
If they compare equal, then the fix I implemented in r39564 is
insufficient. r39564 fixed isues with iterator ordering by removing the
right iterator entirely, so it now does the whole comparison based on keys
from the left iterator, and relies on the (initial) key-count comparison
to ensure no extra keys are in the right hash. But if %hash2{key3}
returns an Undef PMC, it will compare successfully with %hash1{key3}. If
you add an additional "key4" key to %hash2, it will have 3 in total, thus
the hash-count check will also pass and is_deeply() will return a false
positive. So an additional pass on the right hash will need to be
performed, in order to make sure none of its keys are missing from the
left hash (except any that have Undef values).
Either way, we will need further tests to enforce that. And more eyeballs
looking for more corner cases too; it would be nice if is_deeply() worked
correctly as lots of other code should rely on it.
--
Ticket URL: <https://trac.parrot.org/parrot/ticket/763>
Parrot <https://trac.parrot.org/parrot/>
Parrot Development
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