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107 lines
4 KiB
Python
107 lines
4 KiB
Python
from textwrap import dedent
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from typing import Optional, Sequence, Type
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from libcst import PartialParserConfig, parse_module
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from libcst.codemod._codemod import Codemod
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from libcst.codemod._context import CodemodContext
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from libcst.codemod._runner import SkipFile
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from libcst.testing.utils import UnitTest
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# pyre-fixme[13]: This should be an ABC but there are metaclass conflicts due to
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# the way we implement the data_provider decorator, so pyre complains about the
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# uninitialized TRANSFORM below.
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class _CodemodTest:
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"""
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Mixin that can be added to a unit test framework in order to provide
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convenience features. This is provided as an internal-only feature so
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that CodemodTest can be used with other frameworks. This is necessary
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since we set a metaclass on our UnitTest implementation.
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"""
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TRANSFORM: Type[Codemod]
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@staticmethod
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def make_fixture_data(data: str) -> str:
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lines = dedent(data).split("\n")
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def filter_line(line: str) -> str:
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if len(line.strip()) == 0:
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return ""
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return line
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# Get rid of lines that are space only
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lines = [filter_line(line) for line in lines]
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# Get rid of leading and trailing newlines (because of """ style strings)
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while lines and lines[0] == "":
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lines = lines[1:]
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while lines and lines[-1] == "":
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lines = lines[:-1]
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code = "\n".join(lines)
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if not code.endswith("\n"):
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return code + "\n"
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else:
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return code
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def assertCodeEqual(self, expected: str, actual: str) -> None:
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"""
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Given a before and after code string, makes sure they equal. This ensures
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that both the expected and actual are sanitized, so its safe to use this
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on two strings that may have come from a triple-quoted string.
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"""
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# pyre-ignore This mixin needs to be used with a UnitTest subclass.
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self.assertEqual(
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CodemodTest.make_fixture_data(expected),
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CodemodTest.make_fixture_data(actual),
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)
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def assertCodemod(
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self,
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before: str,
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after: str,
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*args: object,
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context_override: Optional[CodemodContext] = None,
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python_version: str = "3.7",
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expected_warnings: Optional[Sequence[str]] = None,
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expected_skip: bool = False,
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**kwargs: object,
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) -> None:
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"""
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Given a before and after string, and optionally any args/kwargs that
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should be passed to the codemod visitor constructor, validate that
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the codemod executes as expected.
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"""
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context = context_override if context_override is not None else CodemodContext()
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transform_instance = self.TRANSFORM(context, *args, **kwargs)
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input_tree = parse_module(
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CodemodTest.make_fixture_data(before),
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config=PartialParserConfig(python_version=python_version),
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)
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try:
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output_tree = transform_instance.transform_module(input_tree)
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except SkipFile:
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if not expected_skip:
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raise
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output_tree = input_tree
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else:
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if expected_skip:
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# pyre-ignore This mixin needs to be used with a UnitTest subclass.
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self.fail("Expected SkipFile but was not raised")
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# pyre-ignore This mixin needs to be used with a UnitTest subclass.
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self.assertEqual(CodemodTest.make_fixture_data(after), output_tree.code)
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if expected_warnings is not None:
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# pyre-ignore This mixin needs to be used with a UnitTest subclass.
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self.assertSequenceEqual(expected_warnings, context.warnings)
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class CodemodTest(_CodemodTest, UnitTest):
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"""
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Base test class for a transform test. Provides facilities for auto-instantiating
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and executing a transform, given the args/kwargs that should be passed to it.
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Set the TRANSFORM class attribute to the class you wish to test and call
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assertCodemod to verify it transforms various code chunks correctly.
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"""
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