Show how @parameterized could replace @data_provider

[lpetre]

Summary

@data_provider seems unnecessary to include in libcst. Why not use a pypi equivalent. Here is an example using parameterized

Let me know what you think and I'll convert the rest of the tests

Test Plan

(libcstvenv) lpetre@lpetre-mbp LibCST % python -m unittest libcst._nodes.tests.test_assert
..........
----------------------------------------------------------------------
Ran 10 tests in 0.080s

OK

[codecov-commenter]

Codecov Report

Merging #558 (842aab3) into main (d0f8fa9) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##             main     #558   +/-   ##
=======================================
  Coverage   94.77%   94.77%           
=======================================
  Files         235      235           
  Lines       23274    23274           
=======================================
  Hits        22058    22058           
  Misses       1216     1216           

Impacted Files	Coverage Δ
libcst/_nodes/tests/test_assert.py	100.00% <100.00%> (ø)

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[zsol]

Do failures look decent? I'm mainly looking for if a failure message includes the inputs or at least some label.
How does this play with pyre?

[lpetre]

Do failures look decent? I'm mainly looking for if a failure message includes the inputs or at least some label.

Error w/ libcst.testing.utils.data_provider

(libcstvenv) lpetre@lpetre-mbp LibCST % python -m unittest libcst._nodes.tests.test_assign
........F................
======================================================================
FAIL: test_valid_6 (libcst._nodes.tests.test_assign.AnnAssignTest)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Users/lpetre/dev/src/github.com/lpetre/LibCST/libcst/testing/utils.py", line 87, in new_test
    return member(self, **data)
  File "/Users/lpetre/dev/src/github.com/lpetre/LibCST/libcst/_nodes/tests/test_assign.py", line 290, in test_valid
    self.validate_node(**kwargs)
  File "/Users/lpetre/dev/src/github.com/lpetre/LibCST/libcst/_nodes/tests/base.py", line 77, in validate_node
    self.__assert_codegen(node, code, expected_position)
  File "/Users/lpetre/dev/src/github.com/lpetre/LibCST/libcst/_nodes/tests/base.py", line 114, in __assert_codegen
    self.assertEqual(module.code_for_node(node), expected)
AssertionError: 'foo :  Optional[str]  =  5' != 'for :  Optional[str]  =  5'
- foo :  Optional[str]  =  5
?   ^
+ for :  Optional[str]  =  5
?   ^

Errors with equivalent parameterized.expand:

(libcstvenv) lpetre@lpetre-mbp LibCST % python -m unittest libcst._nodes.tests.test_assign
........F................
======================================================================
FAIL: test_valid_6_Whitespace_test (libcst._nodes.tests.test_assign.AnnAssignTest)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Users/lpetre/dev/src/github.com/lpetre/libcstvenv/lib/python3.7/site-packages/parameterized/parameterized.py", line 533, in standalone_func
    return func(*(a + p.args), **p.kwargs)
  File "/Users/lpetre/dev/src/github.com/lpetre/LibCST/libcst/_nodes/tests/test_assign.py", line 291, in test_valid
    self.validate_node(**kwargs)
  File "/Users/lpetre/dev/src/github.com/lpetre/LibCST/libcst/_nodes/tests/base.py", line 77, in validate_node
    self.__assert_codegen(node, code, expected_position)
  File "/Users/lpetre/dev/src/github.com/lpetre/LibCST/libcst/_nodes/tests/base.py", line 114, in __assert_codegen
    self.assertEqual(module.code_for_node(node), expected)
AssertionError: 'foo :  Optional[str]  =  5' != 'for :  Optional[str]  =  5'
- foo :  Optional[str]  =  5
?   ^
+ for :  Optional[str]  =  5
?   ^

[lpetre]

How does this play with pyre?

It doesn't. The arguments to the decorator aren't typechecked against the arguments of the test method.

I would argue that migrating to parameterized is better than the broken attempt at typing in data_provider. It doesn't feel like a feature that will be supported any time soon by pyre or mypy.

Generally I question the value of implementing a parameterized testing in libcst (vs a standalone lib)

[zsol]

Generally I question the value of implementing a parameterized testing in libcst (vs a standalone lib)

Fully agree.

Alright, I'm on board :)

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