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

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 `testcode` block.

  This directive supports two options:

  - `hide`, a flag option, hides the output block in other builders. By default it is shown as a literal block without highlighting.
  - `options`, a string option, can be used to give doctest flags (comma-separated) just like in normal doctest blocks.

  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!

There are also these config values for customizing the doctest extension:

`doctest_path`

  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.