Collection matchers

[bpjatfb]

What:

Add Collection matchers, as requested in #346

• AnyContaining(element): A container that contains element
• AnyContainingAll(element_list): A container that contains every element of element_list
• AnyIterable(): Any iterable
• IterableWithElements(element_list): an iterable containing all the elements in element_list in the same order"
• AnyNotEmpty(): An object where len() does not evaluate to zero"
• AnyEmpty(): An object where len() evaluates to zero"

Why:

Currently, the official matchers support Lists and Dicts, but not much in the way of abstract collections. This PR enables patterns like:

actual = deque([1, 2, 3], maxlen=100)
self.assertEqual(actual, IterableWithElements([1, 2, 3]))

How:

I added these matchers to matchers.py alongside their List/Dict counterparts. I added unittests to matchers_unittest.py. Finally, I added documentation in patching/argument_matchers/.

Risks:

No risk of breaking existing code, since these are largely standalone, however there are some edge cases for these matchers that may or may not be intuitive to the user.

• AnyEmpty/AnyNotEmpty rely on len(), so they will throw on AnyEmpty() == iter([1, 2, 3]), for example.
• AnyContaining()/AnyContainingAll() rely on in, so will try to match anything that implements __contains__
  • They may also exhaust iterators leading to unexpected results.

Checklist:

• Added tests, if you've added code that should be tested
• Updated the documentation, if you've changed APIs
• Ensured the test suite passes
• Made sure your code lints
• Completed the Contributor License Agreement ("CLA")

[coveralls]

Pull Request Test Coverage Report for Build 4537294758

• 34 of 37 (91.89%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.03%) to 93.728%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
testslide/matchers.py	34	37	91.89%

Totals
Change from base Build 4472249756:	-0.03%
Covered Lines:	2660
Relevant Lines:	2838

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💛 - Coveralls

[facebook-github-bot]

@deathowl has imported this pull request. If you are a Meta employee, you can view this diff on Phabricator.

[deathowl]

Very nice, imported, feel free to accept ship once internal tests finish

[bpjatfb]

Awesome, thanks @deathowl!

[facebook-github-bot]

@deathowl merged this pull request in 798c9e8.