Function test_output_json

mypy/test/testoutput.py:26–64

Runs Mypy in a subprocess, and ensures that `--output=json` works as intended.

(testcase: DataDrivenTestCase)

def test_output_json(testcase: DataDrivenTestCase) -> None:
    """Runs Mypy in a subprocess, and ensures that `--output=json` works as intended."""
    program_text = "\n".join(testcase.input)
    flags_match = re.search("# flags: (.*)$", program_text, flags=re.MULTILINE)
    if flags_match is not None:
        mypy_cmdline = flags_match.group(1).split()
    else:
        mypy_cmdline = ["--output=json"]
    mypy_cmdline.append(f"--python-version={'.'.join(map(str, PYTHON3_VERSION))}")

    # Write the program to a file.
    program_path = os.path.join(test_temp_dir, "main")
    mypy_cmdline.append(program_path)
    with open(program_path, "w", encoding="utf8") as file:
        for s in testcase.input:
            file.write(f"{s}\n")

    output = []
    # Type check the program.
    out, err, returncode = api.run(mypy_cmdline)
    # split lines, remove newlines, and remove directory of test case
    for line in (out + err).rstrip("\n").splitlines():
        if line.startswith(test_temp_dir + os.sep):
            output.append(line[len(test_temp_dir + os.sep) :].rstrip("\r\n"))
        else:
            output.append(line.rstrip("\r\n"))

    if returncode > 1:
        output.append("!!! Mypy crashed !!!")

    # Remove temp file.
    os.remove(program_path)

    # JSON encodes every `\` character into `\\`, so we need to remove `\\` from windows paths
    # and `/` from POSIX paths
    json_os_separator = os.sep.replace("\\", "\\\\")
    normalized_output = [line.replace(test_temp_dir + json_os_separator, "") for line in output]

    assert normalized_output == testcase.output