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import json
import os
import platform
import subprocess
import pytest
POSITIVE_FILE = "positive.py"
NEGATIVE_FILE = "negative.py"
pytestmark = [
pytest.mark.skipif(
platform.python_implementation() == "PyPy",
reason="MyPy does not work with PyPy yet",
)
]
def get_mypy_cmd(filename: str) -> list[str]:
return ["mypy", "-O", "json", "--strict", filename]
def get_negative_mypy_output() -> str:
"""
Get the output from running mypy on the negative examples file.
"""
process = subprocess.run(
get_mypy_cmd(NEGATIVE_FILE), stdout=subprocess.PIPE, check=False
)
output = process.stdout.decode()
assert output
return output
def get_expected_errors() -> dict[int, str]:
"""
Extract the expected errors from comments in the negative examples file.
"""
with open(NEGATIVE_FILE) as f:
lines = f.readlines()
expected = {}
for idx, line in enumerate(lines):
line = line.rstrip()
if "# error" in line:
expected[idx + 1] = line[line.index("# error") + 9 :]
# Sanity check. Should update if negative.py changes.
assert len(expected) == 9
return expected
def get_mypy_errors() -> dict[int, str]:
"""
Extract the errors from running mypy on the negative examples file.
"""
mypy_output = get_negative_mypy_output()
got = {}
for line in mypy_output.splitlines():
error = json.loads(line)
got[error["line"]] = f"{error['message']} [{error['code']}]"
return got
@pytest.fixture
def chdir_local() -> None:
"""
Change to the local directory. This is so that mypy treats imports from
typeguard as external imports instead of source code (which is handled
differently by mypy).
"""
os.chdir(os.path.dirname(__file__))
@pytest.mark.usefixtures("chdir_local")
def test_positive() -> None:
"""
Run mypy on the positive test file. There should be no errors.
"""
subprocess.check_call(get_mypy_cmd(POSITIVE_FILE))
@pytest.mark.usefixtures("chdir_local")
def test_negative() -> None:
"""
Run mypy on the negative test file. This should fail. The errors from mypy
should match the comments in the file.
"""
got_errors = get_mypy_errors()
expected_errors = get_expected_errors()
if set(got_errors) != set(expected_errors):
raise RuntimeError(
f"Expected error lines {set(expected_errors)} does not "
+ f"match mypy error lines {set(got_errors)}."
)
mismatches = [
(idx, expected_errors[idx], got_errors[idx])
for idx in expected_errors
if expected_errors[idx] != got_errors[idx]
]
for idx, expected, got in mismatches:
print(f"Line {idx}", f"Expected: {expected}", f"Got: {got}", sep="\n\t")
if mismatches:
raise RuntimeError("Error messages changed")
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