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coverage.py

history:20090524T134300, brand new docs.
history:20090613T164000, final touches for 3.0
history:20090618T195900, minor tweaks
history:20090707T205200, changes for 3.0.1
history:20090913T084400, new command line syntax
history:20091004T211900, version 3.1
history:20091127T155100, version 3.2
history:20091205T161429, version 3.2 for real.
history:20100224T204700, version 3.3
history:20100306T181500, version 3.3.1
history:20100725T211700, updated for 3.4.
history:20100820T151500, updated for 3.4b1.
history:20100906T134700, updated for 3.4b2.
history:20100919T163500, updated for 3.4 release.

Coverage.py is a tool for measuring code coverage of Python programs. It monitors your program, noting which parts of the code have been executed, then analyzes the source to identify code that could have been executed but was not.

Coverage measurement is typically used to gauge the effectiveness of tests. It can show which parts of your code are being exercised by tests, and which are not.

The latest version is 3.4, released 19 September 2010. It is supported on Python 2.3 through 3.2 alpha 2.

Quick start

Getting started is easy:

  1. Install coverage.py from the coverage page on the Python Package Index, or by using "easy_install coverage". For a few more details, see :ref:`install`.

  2. Use coverage run to execute your program and gather data:

    $ coverage run my_program.py arg1 arg2
    blah blah ..your program's output.. blah blah
    
  3. Use coverage report to report on the results:

    $ coverage report -m
    Name                      Stmts   Miss  Cover   Missing
    -------------------------------------------------------
    my_program                   20      4    80%   33-35, 39
    my_other_module              56      6    89%   17-23
    -------------------------------------------------------
    TOTAL                        76     10    87%
    
  4. For a nicer presentation, use coverage html to get annotated HTML listings detailing missed lines:

    $ coverage html
    

    Then visit htmlcov/index.html in your browser, to see a report like this.

Using coverage.py

There are a few different ways to use coverage.py. The simplest is the :ref:`command line <cmd>`, which lets you run your program and see the results. If you need more control over how your project is measured, you can use the :ref:`API <api>`.

Some test runners provide coverage integration to make it easy to use coverage while running tests. For example, nose has a cover plug-in.

You can fine-tune coverage's view of your code by directing it to ignore parts that you know aren't interesting. See :ref:`source` and :ref:`excluding` for details.

History

Coverage.py was originally written by Gareth Rees. Since 2004, Ned Batchelder has extended and maintained it with the help of many others. The :ref:`change history <changes>` has all the details.

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