Sphinx

# `sphinx.ext.doctest` – Test snippets in the documentation

It is often helpful to include snippets of code in your documentation and demonstrate the results of executing them. But it is important to ensure that the documentation stays up-to-date with the code.

This extension allows you to test such code snippets in the documentation in a natural way. If you mark the code blocks as shown here, the `doctest` builder will collect them and run them as doctest tests.

Within each document, you can assign each snippet to a group. Each group consists of:

- zero or more setup code blocks (e.g. importing the module to test)

- one or more test blocks

When building the docs with the `doctest` builder, groups are collected for each document and run one after the other, first executing setup code blocks, then the test blocks in the order they appear in the file.

There are two kinds of test blocks:

- doctest-style blocks mimic interactive sessions by interleaving Python code (including the interpreter prompt) and output.

- code-output-style blocks consist of an ordinary piece of Python code, and optionally, a piece of output for that code.

## Directives

The group argument below is interpreted as follows: if it is empty, the block is assigned to the group named `default`. If it is `*`, the block is assigned to all groups (including the `default` group). Otherwise, it must be a comma-separated list of group names.

.. testsetup:: [group]

  A setup code block. This code is not shown in the output for other builders, but executed before the doctests of the group(s) it belongs to.

  Options

  :skipif: condition (text)

    Skip the directive if the python expression condition is True. See skipping tests conditionally.

.. testcleanup:: [group]

  A cleanup code block. This code is not shown in the output for other builders, but executed after the doctests of the group(s) it belongs to.

  Added in version 1.1.

  Options

  :skipif: condition (text)

    Skip the directive if the python expression condition is True. See skipping tests conditionally.

.. doctest:: [group]

  A doctest-style code block. You can use standard `doctest` flags for controlling how actual output is compared with what you give as output. The default set of flags is specified by the `doctest_default_flags` configuration variable.

  Options

  :hide:

    Hide the doctest block in other builders. By default it is shown as a highlighted doctest block.

  :options: doctest flags (comma separated list)

    A comma-separated list of doctest flags that apply to each example in the tests. (You still can give explicit flags per example, with doctest comments, but they will show up in other builders too.)

    Alternatively, you can give inline doctest options, like in doctest:

        >>> datetime.date.now()
        datetime.date(2008, 1, 1)

    They will be respected when the test is run, but by default will be stripped from presentation output. You can prevent stripping using the option `doctest:no-trim-doctest-flags`.

  :pyversion: (text)

    Specify the required Python version for the example to be tested. For instance, in the following case the example will be tested only for Python versions greater than 3.14:

        .. doctest::
           :pyversion: > 3.14

    The following operands are supported:

    - `~=`: Compatible release clause

    - `==`: Version matching clause

    - `!=`: Version exclusion clause

    - `<=`, `>=`: Inclusive ordered comparison clause

    - `<`, `>`: Exclusive ordered comparison clause

    - `===`: Arbitrary equality clause.

    `pyversion` option is followed PEP-440: Version Specifiers.

    Added in version 1.6.

    Changed in version 1.7: Supported PEP-440 operands and notations

  :trim-doctest-flags:
  :no-trim-doctest-flags:

    Whether to trim remove doctest flags (comments looking like `# doctest: FLAG, ...`) at the ends of lines and `<BLANKLINE>` markers individually. Default is `trim-doctest-flags`.

    Note that like with standard doctests, you have to use `<BLANKLINE>` to signal a blank line in the expected output. The `<BLANKLINE>` is removed when building presentation output (HTML, LaTeX etc.).

  :skipif: condition (text)

    Skip the directive if the python expression condition is True. See skipping tests conditionally.

.. testcode:: [group]

  A code block for a code-output-style test.

  Options

  :hide:

    Hide the code block in other builders. By default it is shown as a highlighted code block.

  :trim-doctest-flags:
  :no-trim-doctest-flags:

    Whether to trim remove doctest flags (comments looking like `# doctest: FLAG, ...`) at the ends of lines and `<BLANKLINE>` markers individually. Default is `trim-doctest-flags`.

  :skipif: condition (text)

    Skip the directive if the python expression condition is True. See skipping tests conditionally.

  Note

  Code in a `testcode` block is always executed all at once, no matter how many statements it contains. Therefore, output will not be generated for bare expressions – use `print`. Example:

      .. testcode::

         1+1         # this will give no output!
         print(2+2)  # this will give output

      .. testoutput::

         4

  Also, please be aware that since the doctest module does not support mixing regular output and an exception message in the same snippet, this applies to testcode/testoutput as well.

.. testoutput:: [group]

  The corresponding output, or the exception message, for the last `testcode` block.

  :hide:

    Hide the doctest block in other builders. By default it is shown as a highlighted doctest block.

  :options: doctest flags (comma separated list)

    A comma-separated list of doctest flags.

  :trim-doctest-flags:
  :no-trim-doctest-flags:

    Whether to trim remove doctest flags (comments looking like `# doctest: FLAG, ...`) at the ends of lines and `<BLANKLINE>` markers individually. Default is `trim-doctest-flags`.

  :skipif: condition (text)

    Skip the directive if the python expression condition is True. See skipping tests conditionally.

  Example:

      .. testcode::

         print('Output     text.')

      .. testoutput::
         :hide:
         :options: -ELLIPSIS, +NORMALIZE_WHITESPACE

         Output text.

The following is an example for the usage of the directives. The test via `doctest` and the test via `testcode` and `testoutput` are equivalent.

    The parrot module
    =================

    .. testsetup:: *

       import parrot

    The parrot module is a module about parrots.

    Doctest example:

    .. doctest::

       >>> parrot.voom(3000)
       This parrot wouldn't voom if you put 3000 volts through it!

    Test-Output example:

    .. testcode::

       parrot.voom(3000)

    This would output:

    .. testoutput::

       This parrot wouldn't voom if you put 3000 volts through it!

## Skipping tests conditionally

`skipif`, a string option, can be used to skip directives conditionally. This may be useful e.g. when a different set of tests should be run depending on the environment (hardware, network/VPN, optional dependencies or different versions of dependencies). The `skipif` option is supported by all of the doctest directives. Below are typical use cases for `skipif` when used for different directives:

- `testsetup` and `testcleanup`

  - conditionally skip test setup and/or cleanup

  - customize setup/cleanup code per environment

- `doctest`

  - conditionally skip both a test and its output verification

- `testcode`

  - conditionally skip a test

  - customize test code per environment

- `testoutput`

  - conditionally skip output assertion for a skipped test

  - expect different output depending on the environment

The value of the `skipif` option is evaluated as a Python expression. If the result is a true value, the directive is omitted from the test run just as if it wasn’t present in the file at all.

Instead of repeating an expression, the `doctest_global_setup` configuration option can be used to assign it to a variable which can then be used instead.

Here’s an example which skips some tests if Pandas is not installed:

conf.py

    extensions = ['sphinx.ext.doctest']
    doctest_global_setup = '''
    try:
        import pandas as pd
    except ImportError:
        pd = None
    '''

contents.rst

    .. testsetup::
       :skipif: pd is None

       data = pd.Series([42])

    .. doctest::
       :skipif: pd is None

       >>> data.iloc[0]
       42

    .. testcode::
       :skipif: pd is None

       print(data.iloc[-1])

    .. testoutput::
       :skipif: pd is None

       42

## Configuration

The doctest extension uses the following configuration values:

doctest_default_flags
  Type:
    `int`
  Default:
    `ELLIPSIS | IGNORE_EXCEPTION_DETAIL | DONT_ACCEPT_TRUE_FOR_1`

  By default, these options are enabled:

  - `ELLIPSIS`, allowing you to put ellipses in the expected output that match anything in the actual output;

  - `IGNORE_EXCEPTION_DETAIL`, causing everything following the leftmost colon and any module information in the exception name to be ignored;

  - `DONT_ACCEPT_TRUE_FOR_1`, rejecting “True” in the output where “1” is given – the default behavior of accepting this substitution is a relic of pre-Python 2.2 times.

  Added in version 1.5.

doctest_show_successes
  Type:
    `bool`
  Default:
    `True`

  Controls whether successes are reported.

  For a project with many doctests, it may be useful to set this to `False` to only highlight failures.

  Added in version 7.2.

doctest_path
  Type:
    `Sequence[str]`
  Default:
    `()`

  A list of directories that will be added to `sys.path` when the doctest builder is used. (Make sure it contains absolute paths.)

doctest_global_setup
  Type:
    `str`
  Default:
    `''`

  Python code that is treated like it were put in a `testsetup` directive for every file that is tested, and for every group. You can use this to e.g. import modules you will always need in your doctests.

  Added in version 0.6.

doctest_global_cleanup
  Type:
    `str`
  Default:
    `''`

  Python code that is treated like it were put in a `testcleanup` directive for every file that is tested, and for every group. You can use this to e.g. remove any temporary files that the tests leave behind.

  Added in version 1.1.

doctest_test_doctest_blocks
  Type:
    `str`
  Default:
    `'default'`

  If this is a nonempty string, standard reStructuredText doctest blocks will be tested too. They will be assigned to the group name given.

  reStructuredText doctest blocks are simply doctests put into a paragraph of their own, like so:

      Some documentation text.

      >>> print(1)
      1

      Some more documentation text.

  (Note that no special `::` is used to introduce a doctest block; docutils recognizes them from the leading `>>>`. Also, no additional indentation is used, though it doesn’t hurt.)

  If this value is left at its default value, the above snippet is interpreted by the doctest builder exactly like the following:

      Some documentation text.

      .. doctest::

         >>> print(1)
         1

      Some more documentation text.

  This feature makes it easy for you to test doctests in docstrings included with the `autodoc` extension without marking them up with a special directive.

  Note though that you can’t have blank lines in reStructuredText doctest blocks. They will be interpreted as one block ending and another one starting. Also, removal of `<BLANKLINE>` and `# doctest:` options only works in `doctest` blocks, though you may set `trim_doctest_flags` to achieve that in all code blocks with Python console content.

doctest_fail_fast
  Type:
    `bool`
  Default:
    `False`

  Exit when the first failure is encountered.

  Added in version 9.0.