Function assert_format

tests/util.py:64–111

Convenience function to check that Black formats as expected. You can pass @minimum_version if you're passing code with newer syntax to guard safety guards so they don't just crash with a SyntaxError. Please note this is separate from TargetVerson Mode configuration.

(
    source: str,
    expected: str,
    mode: black.Mode = DEFAULT_MODE,
    *,
    fast: bool = False,
    minimum_version: Optional[Tuple[int, int]] = None,
)

def assert_format(
    source: str,
    expected: str,
    mode: black.Mode = DEFAULT_MODE,
    *,
    fast: bool = False,
    minimum_version: Optional[Tuple[int, int]] = None,
) -> None:
    """Convenience function to check that Black formats as expected.

    You can pass @minimum_version if you're passing code with newer syntax to guard
    safety guards so they don't just crash with a SyntaxError. Please note this is
    separate from TargetVerson Mode configuration.
    """
    _assert_format_inner(
        source, expected, mode, fast=fast, minimum_version=minimum_version
    )

    # For both preview and non-preview tests, ensure that Black doesn't crash on
    # this code, but don't pass "expected" because the precise output may differ.
    try:
        _assert_format_inner(
            source,
            None,
            replace(mode, preview=not mode.preview),
            fast=fast,
            minimum_version=minimum_version,
        )
    except Exception as e:
        text = "non-preview" if mode.preview else "preview"
        raise FormatFailure(
            f"Black crashed formatting this case in {text} mode."
        ) from e
    # Similarly, setting line length to 1 is a good way to catch
    # stability bugs. But only in non-preview mode because preview mode
    # currently has a lot of line length 1 bugs.
    try:
        _assert_format_inner(
            source,
            None,
            replace(mode, preview=False, line_length=1),
            fast=fast,
            minimum_version=minimum_version,
        )
    except Exception as e:
        raise FormatFailure(
            "Black crashed formatting this case with line-length set to 1."
        ) from e


def _assert_format_inner(