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 6.5.0, released September 29, 2022. It is supported on:

  • Python versions 3.7 through 3.11.0 rc2.

  • PyPy3 7.3.8.

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Quick start

Getting started is easy:

  1. Install

    $ pip install coverage

    For more details, see Installation.

  2. Use coverage run to run your test suite and gather data. However you normally run your test suite, you can run your test runner under coverage. If your test runner command starts with “python”, just replace the initial “python” with “coverage run”.

    Instructions for specific test runners:

    • pytest

      If you usually use:

      $ pytest arg1 arg2 arg3

      then you can run your tests under coverage with:

      $ coverage run -m pytest arg1 arg2 arg3

      Many people choose to use the pytest-cov plugin, but for most purposes, it is unnecessary.

    • unittest

      Change “python” to “coverage run”, so this:

      $ python -m unittest discover


      $ coverage run -m unittest discover

    To limit coverage measurement to code in the current directory, and also find files that weren’t executed at all, add the --source=. argument to your coverage command line.

  3. Use coverage report to report on the results:

    $ coverage report -m
    Name                      Stmts   Miss  Cover   Missing
    -------------------------------------------------------                20      4    80%   33-35, 39           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 open htmlcov/index.html in your browser, to see a report like this.

Capabilities can do a number of things:


There are a few different ways to use The simplest is the command line, 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 API.

Some test runners provide coverage integration to make it easy to use while running tests. For example, pytest has the pytest-cov plugin.

You can fine-tune’s view of your code by directing it to ignore parts that you know aren’t interesting. See Specifying source files and Excluding code from for details.

Getting help

If the FAQ doesn’t answer your question, you can discuss or get help using it on the Testing In Python mailing list.

Bug reports are gladly accepted at the GitHub issue tracker. GitHub also hosts the code repository.

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