Black compatible configurations

All of Black’s changes are harmless (or at least, they should be), but a few do conflict against other tools. It is not uncommon to be using other tools alongside Black like linters and type checkers. Some of them need a bit of tweaking to resolve the conflicts. Listed below are Black compatible configurations in various formats for the common tools out there.

Please note that Black only supports the TOML file format for its configuration (e.g. pyproject.toml). The provided examples are to only configure their corresponding tools, using their supported file formats.

Compatible configuration files can be found here.

isort

isort helps to sort and format imports in your Python code. Black also formats imports, but in a different way from isort’s defaults which leads to conflicting changes.

Configuration

multi_line_output = 3
include_trailing_comma = True
force_grid_wrap = 0
use_parentheses = True
ensure_newline_before_comments = True
line_length = 88

Why those options above?

Black wraps imports that surpass line-length by moving identifiers into their own indented line. If that still doesn’t fit the bill, it will put all of them in separate lines and put a trailing comma. A more detailed explanation of this behaviour can be found here.

isort’s default mode of wrapping imports that extend past the line_length limit is “Grid”.

from third_party import (lib1, lib2, lib3,
                         lib4, lib5, ...)

This style is incompatible with Black, but isort can be configured to use a different wrapping mode called “Vertical Hanging Indent” which looks like this:

from third_party import (
    lib1,
    lib2,
    lib3,
    lib4,
)

This style is Black compatible and can be achieved by multi-line-output = 3. Also, as mentioned above, when wrapping long imports Black puts a trailing comma and uses parentheses. isort should follow the same behaviour and passing the options include_trailing_comma = True and use_parentheses = True configures that.

The option force_grid_wrap = 0 is just to tell isort to only wrap imports that surpass the line_length limit.

Finally, isort should be told to wrap imports when they surpass Black’s default limit of 88 characters via line_length = 88 as well as ensure_newline_before_comments = True to ensure spacing import sections with comments works the same as with Black.

Please note ensure_newline_before_comments = True only works since isort >= 5 but does not break older versions so you can keep it if you are running previous versions. If only isort >= 5 is used you can add profile = black instead of all the options since profiles are available and do the configuring for you.

Formats

.isort.cfg
[settings]
multi_line_output = 3
include_trailing_comma = True
force_grid_wrap = 0
use_parentheses = True
ensure_newline_before_comments = True
line_length = 88
setup.cfg
[isort]
multi_line_output = 3
include_trailing_comma = True
force_grid_wrap = 0
use_parentheses = True
ensure_newline_before_comments = True
line_length = 88
pyproject.toml
[tool.isort]
multi_line_output = 3
include_trailing_comma = true
force_grid_wrap = 0
use_parentheses = true
ensure_newline_before_comments = true
line_length = 88
.editorconfig
[*.py]
multi_line_output = 3
include_trailing_comma = True
force_grid_wrap = 0
use_parentheses = True
ensure_newline_before_comments = True
line_length = 88

Flake8

Flake8 is a code linter. It warns you of syntax errors, possible bugs, stylistic errors, etc. For the most part, Flake8 follows PEP 8 when warning about stylistic errors. There are a few deviations that cause incompatibilities with Black.

Configuration

max-line-length = 88
extend-ignore = E203

Why those options above?

In some cases, as determined by PEP 8, Black will enforce an equal amount of whitespace around slice operators. Due to this, Flake8 will raise E203 whitespace before ':' warnings. Since this warning is not PEP 8 compliant, Flake8 should be configured to ignore it via extend-ignore = E203.

When breaking a line, Black will break it before a binary operator. This is compliant with PEP 8 as of April 2016. There’s a disabled-by-default warning in Flake8 which goes against this PEP 8 recommendation called W503 line break before binary operator. It should not be enabled in your configuration.

Also, as like with isort, flake8 should be configured to allow lines up to the length limit of 88, Black’s default. This explains max-line-length = 88.

Formats

.flake8
[flake8]
max-line-length = 88
extend-ignore = E203
setup.cfg
[flake8]
max-line-length = 88
extend-ignore = E203
tox.ini
[flake8]
max-line-length = 88
extend-ignore = E203

Pylint

Pylint is also a code linter like Flake8. It has the same checks as flake8 and more. In particular, it has more formatting checks regarding style conventions like variable naming. With so many checks, Pylint is bound to have some mixed feelings about Black’s formatting style.

Configuration

disable = C0330, C0326
max-line-length = 88

Why those options above?

When Black is folding very long expressions, the closing brackets will be dedented.

ImportantClass.important_method(
    exc, limit, lookup_lines, capture_locals, callback
)

Although, this style is PEP 8 compliant, Pylint will raise C0330: Wrong hanging indentation before block (add 4 spaces) warnings. Since Black isn’t configurable on this style, Pylint should be told to ignore these warnings via disable = C0330.

Also, since Black deals with whitespace around operators and brackets, Pylint’s warning C0326: Bad whitespace should be disabled using disable = C0326.

And as usual, Pylint should be configured to only complain about lines that surpass 88 characters via max-line-length = 88.

Formats

pylintrc
[MESSAGES CONTROL]
disable = C0330, C0326

[format]
max-line-length = 88
setup.cfg
[pylint]
max-line-length = 88

[pylint.messages_control]
disable = C0330, C0326
pyproject.toml
[tool.pylint.messages_control]
disable = "C0330, C0326"

[tool.pylint.format]
max-line-length = "88"