Initial commit: add .gitignore and README

.venv/lib/python3.12/site-packages/mypy/test/meta/_pytest.py

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+import shlex
+import subprocess
+import sys
+import textwrap
+import uuid
+from collections.abc import Iterable
+from dataclasses import dataclass
+from pathlib import Path
+
+from mypy.test.config import test_data_prefix
+
+
+@dataclass
+class PytestResult:
+    input: str
+    input_updated: str  # any updates made by --update-data
+    stdout: str
+    stderr: str
+
+
+def dedent_docstring(s: str) -> str:
+    return textwrap.dedent(s).lstrip()
+
+
+def run_pytest_data_suite(
+    data_suite: str,
+    *,
+    data_file_prefix: str = "check",
+    pytest_node_prefix: str = "mypy/test/testcheck.py::TypeCheckSuite",
+    extra_args: Iterable[str],
+    max_attempts: int,
+) -> PytestResult:
+    """
+    Runs a suite of data test cases through pytest until either tests pass
+    or until a maximum number of attempts (needed for incremental tests).
+
+    :param data_suite: the actual "suite" i.e. the contents of a .test file
+    """
+    p_test_data = Path(test_data_prefix)
+    p_root = p_test_data.parent.parent
+    p = p_test_data / f"{data_file_prefix}-meta-{uuid.uuid4()}.test"
+    assert not p.exists()
+    data_suite = dedent_docstring(data_suite)
+    try:
+        p.write_text(data_suite)
+
+        test_nodeid = f"{pytest_node_prefix}::{p.name}"
+        extra_args = [sys.executable, "-m", "pytest", "-n", "0", "-s", *extra_args, test_nodeid]
+        cmd = shlex.join(extra_args)
+        for i in range(max_attempts - 1, -1, -1):
+            print(f">> {cmd}")
+            proc = subprocess.run(extra_args, capture_output=True, check=False, cwd=p_root)
+            if proc.returncode == 0:
+                break
+            prefix = "NESTED PYTEST STDOUT"
+            for line in proc.stdout.decode().splitlines():
+                print(f"{prefix}: {line}")
+                prefix = " " * len(prefix)
+            prefix = "NESTED PYTEST STDERR"
+            for line in proc.stderr.decode().splitlines():
+                print(f"{prefix}: {line}")
+                prefix = " " * len(prefix)
+            print(f"Exit code {proc.returncode} ({i} attempts remaining)")
+
+        return PytestResult(
+            input=data_suite,
+            input_updated=p.read_text(),
+            stdout=proc.stdout.decode(),
+            stderr=proc.stderr.decode(),
+        )
+    finally:
+        p.unlink()

.venv/lib/python3.12/site-packages/mypy/test/meta/test_diff_helper.py

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+import io
+
+from mypy.test.helpers import Suite, diff_ranges, render_diff_range
+
+
+class DiffHelperSuite(Suite):
+    def test_render_diff_range(self) -> None:
+        expected = ["hello", "world"]
+        actual = ["goodbye", "world"]
+
+        expected_ranges, actual_ranges = diff_ranges(expected, actual)
+
+        output = io.StringIO()
+        render_diff_range(expected_ranges, expected, output=output)
+        assert output.getvalue() == "  hello (diff)\n  world\n"
+        output = io.StringIO()
+        render_diff_range(actual_ranges, actual, output=output)
+        assert output.getvalue() == "  goodbye (diff)\n  world\n"
+
+        expected = ["a", "b", "c", "d", "e", "f", "g", "h", "circle", "i", "j"]
+        actual = ["a", "b", "c", "d", "e", "f", "g", "h", "square", "i", "j"]
+
+        expected_ranges, actual_ranges = diff_ranges(expected, actual)
+
+        output = io.StringIO()
+        render_diff_range(expected_ranges, expected, output=output, indent=0)
+        assert output.getvalue() == "a\nb\nc\n...\nf\ng\nh\ncircle (diff)\ni\nj\n"
+        output = io.StringIO()
+        render_diff_range(actual_ranges, actual, output=output, indent=0)
+        assert output.getvalue() == "a\nb\nc\n...\nf\ng\nh\nsquare (diff)\ni\nj\n"
+
+    def test_diff_ranges(self) -> None:
+        a = ["hello", "world"]
+        b = ["hello", "world"]
+
+        assert diff_ranges(a, b) == (
+            [(0, 0), (0, 2), (2, 2), (2, 2)],
+            [(0, 0), (0, 2), (2, 2), (2, 2)],
+        )
+
+        a = ["hello", "world"]
+        b = ["goodbye", "world"]
+
+        assert diff_ranges(a, b) == (
+            [(0, 1), (1, 2), (2, 2), (2, 2)],
+            [(0, 1), (1, 2), (2, 2), (2, 2)],
+        )

.venv/lib/python3.12/site-packages/mypy/test/meta/test_parse_data.py

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+"""
+A "meta test" which tests the parsing of .test files. This is not meant to become exhaustive
+but to ensure we maintain a basic level of ergonomics for mypy contributors.
+"""
+
+from mypy.test.helpers import Suite
+from mypy.test.meta._pytest import PytestResult, run_pytest_data_suite
+
+
+def _run_pytest(data_suite: str) -> PytestResult:
+    return run_pytest_data_suite(data_suite, extra_args=[], max_attempts=1)
+
+
+class ParseTestDataSuite(Suite):
+    def test_parse_invalid_case(self) -> None:
+        # Act
+        result = _run_pytest(
+            """
+            [case abc]
+            s: str
+            [case foo-XFAIL]
+            s: str
+            """
+        )
+
+        # Assert
+        assert "Invalid testcase id 'foo-XFAIL'" in result.stdout
+
+    def test_parse_invalid_section(self) -> None:
+        # Act
+        result = _run_pytest(
+            """
+            [case abc]
+            s: str
+            [unknownsection]
+            abc
+            """
+        )
+
+        # Assert
+        expected_lineno = result.input.splitlines().index("[unknownsection]") + 1
+        expected = (
+            f".test:{expected_lineno}: Invalid section header [unknownsection] in case 'abc'"
+        )
+        assert expected in result.stdout
+
+    def test_bad_ge_version_check(self) -> None:
+        # Act
+        actual = _run_pytest(
+            """
+            [case abc]
+            s: str
+            [out version>=3.9]
+            abc
+            """
+        )
+
+        # Assert
+        assert "version>=3.9 always true since minimum runtime version is (3, 9)" in actual.stdout
+
+    def test_bad_eq_version_check(self) -> None:
+        # Act
+        actual = _run_pytest(
+            """
+            [case abc]
+            s: str
+            [out version==3.7]
+            abc
+            """
+        )
+
+        # Assert
+        assert "version==3.7 always false since minimum runtime version is (3, 9)" in actual.stdout

.venv/lib/python3.12/site-packages/mypy/test/meta/test_update_data.py

@@ -0,0 +1,135 @@
+"""
+A "meta test" which tests the `--update-data` feature for updating .test files.
+Updating the expected output, especially when it's in the form of inline (comment) assertions,
+can be brittle, which is why we're "meta-testing" here.
+"""
+
+from mypy.test.helpers import Suite
+from mypy.test.meta._pytest import PytestResult, dedent_docstring, run_pytest_data_suite
+
+
+def _run_pytest_update_data(data_suite: str) -> PytestResult:
+    """
+    Runs a suite of data test cases through 'pytest --update-data' until either tests pass
+    or until a maximum number of attempts (needed for incremental tests).
+    """
+    return run_pytest_data_suite(data_suite, extra_args=["--update-data"], max_attempts=3)
+
+
+class UpdateDataSuite(Suite):
+    def test_update_data(self) -> None:
+        # Note: We test multiple testcases rather than 'test case per test case'
+        #       so we could also exercise rewriting multiple testcases at once.
+        result = _run_pytest_update_data(
+            """
+            [case testCorrect]
+            s: str = 42  # E: Incompatible types in assignment (expression has type "int", variable has type "str")
+
+            [case testWrong]
+            s: str = 42  # E: wrong error
+
+            [case testXfail-xfail]
+            s: str = 42  # E: wrong error
+
+            [case testWrongMultiline]
+            s: str = 42  # E: foo \
+                         # N: bar
+
+            [case testMissingMultiline]
+            s: str = 42;  i: int = 'foo'
+
+            [case testExtraneous]
+            s: str = 'foo'  # E: wrong error
+
+            [case testExtraneousMultiline]
+            s: str = 'foo'  # E: foo \
+                            # E: bar
+
+            [case testExtraneousMultilineNonError]
+            s: str = 'foo'  # W: foo \
+                            # N: bar
+
+            [case testOutCorrect]
+            s: str = 42
+            [out]
+            main:1: error: Incompatible types in assignment (expression has type "int", variable has type "str")
+
+            [case testOutWrong]
+            s: str = 42
+            [out]
+            main:1: error: foobar
+
+            [case testOutWrongIncremental]
+            s: str = 42
+            [out]
+            main:1: error: foobar
+            [out2]
+            main:1: error: foobar
+
+            [case testWrongMultipleFiles]
+            import a, b
+            s: str = 42  # E: foo
+            [file a.py]
+            s1: str = 42  # E: bar
+            [file b.py]
+            s2: str = 43  # E: baz
+            [builtins fixtures/list.pyi]
+            """
+        )
+
+        # Assert
+        expected = dedent_docstring(
+            """
+        [case testCorrect]
+        s: str = 42  # E: Incompatible types in assignment (expression has type "int", variable has type "str")
+
+        [case testWrong]
+        s: str = 42  # E: Incompatible types in assignment (expression has type "int", variable has type "str")
+
+        [case testXfail-xfail]
+        s: str = 42  # E: wrong error
+
+        [case testWrongMultiline]
+        s: str = 42  # E: Incompatible types in assignment (expression has type "int", variable has type "str")
+
+        [case testMissingMultiline]
+        s: str = 42;  i: int = 'foo'  # E: Incompatible types in assignment (expression has type "int", variable has type "str") \\
+                                      # E: Incompatible types in assignment (expression has type "str", variable has type "int")
+
+        [case testExtraneous]
+        s: str = 'foo'
+
+        [case testExtraneousMultiline]
+        s: str = 'foo'
+
+        [case testExtraneousMultilineNonError]
+        s: str = 'foo'
+
+        [case testOutCorrect]
+        s: str = 42
+        [out]
+        main:1: error: Incompatible types in assignment (expression has type "int", variable has type "str")
+
+        [case testOutWrong]
+        s: str = 42
+        [out]
+        main:1: error: Incompatible types in assignment (expression has type "int", variable has type "str")
+
+        [case testOutWrongIncremental]
+        s: str = 42
+        [out]
+        main:1: error: Incompatible types in assignment (expression has type "int", variable has type "str")
+        [out2]
+        main:1: error: Incompatible types in assignment (expression has type "int", variable has type "str")
+
+        [case testWrongMultipleFiles]
+        import a, b
+        s: str = 42  # E: Incompatible types in assignment (expression has type "int", variable has type "str")
+        [file a.py]
+        s1: str = 42  # E: Incompatible types in assignment (expression has type "int", variable has type "str")
+        [file b.py]
+        s2: str = 43  # E: Incompatible types in assignment (expression has type "int", variable has type "str")
+        [builtins fixtures/list.pyi]
+        """
+        )
+        assert result.input_updated == expected