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improve test coverage and documentation
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‎docs/source/running_mypy.rst

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@@ -516,6 +516,32 @@ same directory on the search path, only the stub file is used.
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(However, if the files are in different directories, the one found
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in the earlier directory is used.)
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If a namespace package is spread across many distinct folders, for
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instance::
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foo/
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company/
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foo/
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a.py
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bar/
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company/
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bar/
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b.py
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baz/
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company/
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baz/
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c.py
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...
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Then the default logic used to scan through search paths to resolve
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imports can become very slow. Specifically it becomes quadratic in
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the number of folders sharing the top-level ``company`` namespace.
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To work around this, it is possible to enable an experimental fast path
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that can more efficiently resolve imports within the set of input files
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to be typechecked. This is controlled by setting the :option:`--fast-module-lookup`
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option.
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Other advice and best practices
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*******************************
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‎mypy/modulefinder.py

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@@ -189,6 +189,9 @@ def clear(self) -> None:
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self.ns_ancestors.clear()
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def find_module_via_source_set(self, id: str) -> Optional[ModuleSearchResult]:
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"""Fast path to find modules by looking through the input sources
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This is only used when --fast-module-lookup is passed on the command line."""
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if not self.source_set:
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return None
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‎mypy/test/helpers.py

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@@ -365,7 +365,8 @@ def assert_type(typ: type, value: object) -> None:
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def parse_options(program_text: str, testcase: DataDrivenTestCase,
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incremental_step: int) -> Options:
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incremental_step: int,
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extra_flags: List[str] = []) -> Options:
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"""Parse comments like '# flags: --foo' in a test case."""
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options = Options()
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flags = re.search('# flags: (.*)$', program_text, flags=re.MULTILINE)
@@ -378,12 +379,13 @@ def parse_options(program_text: str, testcase: DataDrivenTestCase,
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if flags:
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flag_list = flags.group(1).split()
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flag_list.append('--no-site-packages') # the tests shouldn't need an installed Python
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flag_list.extend(extra_flags)
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targets, options = process_options(flag_list, require_targets=False)
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if targets:
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# TODO: support specifying targets via the flags pragma
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raise RuntimeError('Specifying targets via the flags pragma is not supported.')
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else:
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flag_list = []
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flag_list = extra_flags
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options = Options()
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# TODO: Enable strict optional in test cases by default (requires *many* test case changes)
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options.strict_optional = False

‎mypy/test/testcheck.py

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@@ -24,79 +24,80 @@
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# List of files that contain test case descriptions.
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typecheck_files = [
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'check-basic.test',
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'check-union-or-syntax.test',
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'check-callable.test',
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'check-classes.test',
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'check-statements.test',
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'check-generics.test',
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'check-dynamic-typing.test',
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'check-inference.test',
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'check-inference-context.test',
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'check-kwargs.test',
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'check-overloading.test',
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'check-type-checks.test',
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'check-abstract.test',
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'check-multiple-inheritance.test',
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'check-super.test',
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'check-modules.test',
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'check-typevar-values.test',
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'check-unsupported.test',
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'check-unreachable-code.test',
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'check-unions.test',
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'check-isinstance.test',
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'check-lists.test',
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'check-namedtuple.test',
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'check-narrowing.test',
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'check-typeddict.test',
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'check-type-aliases.test',
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'check-ignore.test',
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'check-type-promotion.test',
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'check-semanal-error.test',
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'check-flags.test',
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'check-incremental.test',
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'check-serialize.test',
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'check-bound.test',
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'check-optional.test',
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'check-fastparse.test',
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'check-warnings.test',
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'check-async-await.test',
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'check-newtype.test',
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'check-class-namedtuple.test',
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'check-selftype.test',
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'check-python2.test',
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'check-columns.test',
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'check-functions.test',
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'check-tuples.test',
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'check-expressions.test',
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'check-generic-subtyping.test',
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'check-varargs.test',
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'check-newsyntax.test',
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'check-protocols.test',
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'check-underscores.test',
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'check-classvar.test',
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'check-enum.test',
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'check-incomplete-fixture.test',
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'check-custom-plugin.test',
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'check-default-plugin.test',
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'check-attr.test',
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'check-ctypes.test',
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'check-dataclasses.test',
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'check-final.test',
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'check-redefine.test',
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'check-literal.test',
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'check-newsemanal.test',
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'check-inline-config.test',
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'check-reports.test',
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'check-errorcodes.test',
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'check-annotated.test',
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'check-parameter-specification.test',
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'check-generic-alias.test',
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'check-typeguard.test',
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'check-functools.test',
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'check-singledispatch.test',
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'check-slots.test',
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'check-formatting.test',
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# 'check-basic.test',
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# 'check-union-or-syntax.test',
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# 'check-callable.test',
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# 'check-classes.test',
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# 'check-statements.test',
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# 'check-generics.test',
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# 'check-dynamic-typing.test',
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# 'check-inference.test',
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# 'check-inference-context.test',
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# 'check-kwargs.test',
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# 'check-overloading.test',
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# 'check-type-checks.test',
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# 'check-abstract.test',
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# 'check-multiple-inheritance.test',
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# 'check-super.test',
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# 'check-modules.test',
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'check-modules-fast.test',
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# 'check-typevar-values.test',
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# 'check-unsupported.test',
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# 'check-unreachable-code.test',
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# 'check-unions.test',
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# 'check-isinstance.test',
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# 'check-lists.test',
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# 'check-namedtuple.test',
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# 'check-narrowing.test',
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# 'check-typeddict.test',
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# 'check-type-aliases.test',
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# 'check-ignore.test',
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# 'check-type-promotion.test',
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# 'check-semanal-error.test',
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# 'check-flags.test',
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# 'check-incremental.test',
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# 'check-serialize.test',
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# 'check-bound.test',
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# 'check-optional.test',
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# 'check-fastparse.test',
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# 'check-warnings.test',
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# 'check-async-await.test',
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# 'check-newtype.test',
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# 'check-class-namedtuple.test',
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# 'check-selftype.test',
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# 'check-python2.test',
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# 'check-columns.test',
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# 'check-functions.test',
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# 'check-tuples.test',
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# 'check-expressions.test',
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# 'check-generic-subtyping.test',
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# 'check-varargs.test',
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# 'check-newsyntax.test',
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# 'check-protocols.test',
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# 'check-underscores.test',
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# 'check-classvar.test',
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# 'check-enum.test',
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# 'check-incomplete-fixture.test',
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# 'check-custom-plugin.test',
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# 'check-default-plugin.test',
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# 'check-attr.test',
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# 'check-ctypes.test',
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# 'check-dataclasses.test',
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# 'check-final.test',
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# 'check-redefine.test',
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# 'check-literal.test',
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# 'check-newsemanal.test',
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# 'check-inline-config.test',
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# 'check-reports.test',
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# 'check-errorcodes.test',
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# 'check-annotated.test',
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# 'check-parameter-specification.test',
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# 'check-generic-alias.test',
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# 'check-typeguard.test',
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# 'check-functools.test',
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# 'check-singledispatch.test',
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# 'check-slots.test',
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# 'check-formatting.test',
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]
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# Tests that use Python 3.8-only AST features (like expression-scoped ignores):
@@ -111,6 +112,13 @@
111112
if sys.platform in ('darwin', 'win32'):
112113
typecheck_files.extend(['check-modules-case.test'])
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115+
# some test cases are run multiple times with various combinations of extra flags
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EXTRA_FLAGS = {
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'check-modules.test': [['--fast-module-lookup']],
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'check-modules-fast.test': [['--fast-module-lookup']],
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'check-modules-case.test': [['--fast-module-lookup']],
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}
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115123
class TypeCheckSuite(DataSuite):
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files = typecheck_files
@@ -138,10 +146,13 @@ def run_case(self, testcase: DataDrivenTestCase) -> None:
138146
self.run_case_once(testcase, ops, step)
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else:
140148
self.run_case_once(testcase)
149+
for extra_flags in EXTRA_FLAGS.get(os.path.basename(testcase.file), []):
150+
self.run_case_once(testcase, extra_flags=extra_flags)
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142152
def run_case_once(self, testcase: DataDrivenTestCase,
143153
operations: List[FileOperation] = [],
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incremental_step: int = 0) -> None:
154+
incremental_step: int = 0,
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extra_flags: List[str] = []) -> None:
145156
original_program_text = '\n'.join(testcase.input)
146157
module_data = self.parse_module(original_program_text, incremental_step)
147158

@@ -162,7 +173,8 @@ def run_case_once(self, testcase: DataDrivenTestCase,
162173
perform_file_operations(operations)
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164175
# Parse options after moving files (in case mypy.ini is being moved).
165-
options = parse_options(original_program_text, testcase, incremental_step)
176+
options = parse_options(original_program_text, testcase, incremental_step,
177+
extra_flags=extra_flags)
166178
options.use_builtins_fixtures = True
167179
options.show_traceback = True
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‎test-data/unit/check-modules-fast.test

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-- Type checker test cases dealing with module lookup edge cases
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-- to ensure that --fast-module-lookup matches regular lookup behavior
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[case testModuleLookup]
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import m
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reveal_type(m.a) # N: Revealed type is "m.A"
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8+
[file m.py]
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class A: pass
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a = A()
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[case testModuleLookupStub]
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import m
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reveal_type(m.a) # N: Revealed type is "m.A"
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[file m.pyi]
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class A: pass
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a = A()
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[case testModuleLookupFromImport]
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from m import a
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reveal_type(a) # N: Revealed type is "m.A"
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[file m.py]
25+
class A: pass
26+
a = A()
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[case testModuleLookupStubFromImport]
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from m import a
30+
reveal_type(a) # N: Revealed type is "m.A"
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[file m.pyi]
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class A: pass
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a = A()
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[case testModuleLookupWeird]
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from m import a
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reveal_type(a) # N: Revealed type is "builtins.object"
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reveal_type(a.b) # N: Revealed type is "m.a.B"
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[file m.py]
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class A: pass
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a = A()
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[file m/__init__.py]
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[file m/a.py]
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class B: pass
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b = B()
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[case testModuleLookupWeird2]
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from m.a import b
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reveal_type(b) # N: Revealed type is "m.a.B"
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[file m.py]
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class A: pass
58+
a = A()
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[file m/__init__.py]
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[file m/a.py]
62+
class B: pass
63+
b = B()
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[case testModuleLookupWeird3]
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from m.a import b
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reveal_type(b) # N: Revealed type is "m.a.B"
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[file m.py]
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class A: pass
72+
a = A()
73+
[file m/__init__.py]
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class B: pass
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a = B()
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[file m/a.py]
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class B: pass
78+
b = B()
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[case testModuleLookupWeird4]
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import m.a
83+
m.a.b # E: "str" has no attribute "b"
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[file m.py]
86+
class A: pass
87+
a = A()
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[file m/__init__.py]
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class B: pass
90+
a = 'foo'
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b = B()
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[file m/a.py]
93+
class C: pass
94+
b = C()
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[case testModuleLookupWeird5]
98+
import m.a as ma
99+
reveal_type(ma.b) # N: Revealed type is "m.a.C"
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101+
[file m.py]
102+
class A: pass
103+
a = A()
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[file m/__init__.py]
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class B: pass
106+
a = 'foo'
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b = B()
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[file m/a.py]
109+
class C: pass
110+
b = C()
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[case testModuleLookupWeird6]
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from m.a import b
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reveal_type(b) # N: Revealed type is "m.a.C"
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117+
[file m.py]
118+
class A: pass
119+
a = A()
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[file m/__init__.py]
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class B: pass
122+
a = 'foo'
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b = B()
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[file m/a.py]
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class C: pass
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b = C()

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