sphinx.ext.doctest – Test snippets in the documentation

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2023-12-01

This extension allows you to test snippets in the documentation in a natural way. It works by collecting specially-marked up code blocks and running them as doctest tests.

Within one document, test code is partitioned in groups, where 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.

The doctest extension provides four directives. The group argument 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.

.. 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.

New in version 1.1.

.. 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. 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 (not comparing tracebacks), DONT_ACCEPT_TRUE_FOR_1 (by default, doctest accepts “True” in the output where “1” is given – this is a relic of pre-Python 2.2 times).

This directive supports two options:

hide, a flag option, hides the doctest block in other builders. By default it is shown as a highlighted doctest block.
options, a string option, can be used to give 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.)

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.).

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

>>> datetime.date.now()   # doctest: +SKIP
datetime.date(2008, 1, 1)

They will be respected when the test is run, but stripped from presentation output.

.. testcode:: [group]

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

This directive supports one option:

hide, a flag option, hides the code block in other builders. By default it is shown as a highlighted code block.

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; 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

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.

New in version 0.6.

doctest_global_cleanup

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.

New in version 1.1.

doctest_test_doctest_blocks

If this is a nonempty string (the default is 'default'), standard reST doctest blocks will be tested too. They will be assigned to the group name given.

reST 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 reST 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.