Doctest Formatting

While Black makes some decisions about styling for docstrings, it does not make any assumptions about the contents of documentation. Thus, executable Python code inside docstrings or documentation files (e.g. doctests), will not be formatted by Black.

Listed below are tools that apply Black formatting to code inside docstrings and documentation files.

Note: There are some observed inconsistencies between the below packages. Because of this, we hesitate to make any recommendations. Any installed packages are installed at your own risk. We also encourage anyone to contribute documentation for additional packages that apply Black formatting to doctests.

blacken-docs

blacken-docs is primarily used to apply Black formatting to code in documentation files (e.g. .rst, .md, .tex).

blacken-docs supports the following:

Python code blocks in Markdown, reStructuredText, and LaTeX files. Similar to blackdoc, normal Black formatting is applied, so doctests inside Python code blocks will not be formatted.
md
```
```python
print("Hello world!")
```
```
rst
```
.. code-block:: python
    print("Hello world!")
```
latex
```
\begin{minted}{python}
print("Hello world!")
\end{minted}
```

Doctests inside Pycon code blocks in Markdown and reStructuredText. The code blocks may be included in a .md or .rst file, or inside a docstring in a Python file.

```python
>>> print("Hello world!")
```

rst

.. code-block:: pycon
    >>> print("Hello world!")

python

def add_one(n: int) -> int:
    """
    Examples
    --------
    ```pycon
    >>> add_one(1) == 2
    ```
    """
    return n + 1

blackdoc

blackdoc is primarily used to apply Black formatting to doctests in Python files. It will not format any file contents that are otherwise covered by Black.

blackdoc supports the following:

Doctests in Python files.

python

def add_one(n: int) -> int:
    """
    Examples
    --------
    >>> add_one(1) == 2
    """
    return n + 1

Python code blocks in Markdown or reStructuredText files. In these cases, normal Black formatting is applied, i.e., doctests inside Python code blocks will not be formatted.
md
```
```python
print("Hello world!")
```
```
rst
```
.. code-block:: python
    print("Hello world!")
```