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pytest-cov /

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pytest-cov

This plugin produces coverage reports. It supports centralised testing and distributed testing in both load and each modes. It also supports coverage of subprocesses.

All features offered by the coverage package should be available, either through pytest-cov or through coverage's config file.

Installation

The pytest-cov package may be installed with pip or easy_install:

pip install pytest-cov
easy_install pytest-cov

Uninstallation

Uninstalling packages is supported by pip:

pip uninstall pytest-cov

However easy_install does not provide an uninstall facility.

Important

Ensure that you manually delete the init_cov_core.pth file in your site-packages directory.

This file starts coverage collection of subprocesses if appropriate during site initialisation at python startup.

Usage

Centralised Testing

Centralised testing will report on the combined coverage of the main process and all of it's subprocesses.

Running centralised testing:

py.test --cov myproj tests/

Shows a terminal report:

-------------------- coverage: platform linux2, python 2.6.4-final-0 ---------------------
Name                 Stmts   Miss  Cover
----------------------------------------
myproj/__init__          2      0   100%
myproj/myproj          257     13    94%
myproj/feature4286      94      7    92%
----------------------------------------
TOTAL                  353     20    94%

Distributed Testing: Load

Distributed testing with dist mode set to load will report on the combined coverage of all slaves. The slaves may be spread out over any number of hosts and each slave may be located anywhere on the file system. Each slave will have it's subprocesses measured.

Running distributed testing with dist mode set to load:

py.test --cov myproj -n 2 tests/

Shows a terminal report:

-------------------- coverage: platform linux2, python 2.6.4-final-0 ---------------------
Name                 Stmts   Miss  Cover
----------------------------------------
myproj/__init__          2      0   100%
myproj/myproj          257     13    94%
myproj/feature4286      94      7    92%
----------------------------------------
TOTAL                  353     20    94%

Again but spread over different hosts and different directories:

py.test --cov myproj --dist load
        --tx ssh=memedough@host1//chdir=testenv1
        --tx ssh=memedough@host2//chdir=/tmp/testenv2//python=/tmp/env1/bin/python
        --rsyncdir myproj --rsyncdir tests --rsync examples
        tests/

Shows a terminal report:

-------------------- coverage: platform linux2, python 2.6.4-final-0 ---------------------
Name                 Stmts   Miss  Cover
----------------------------------------
myproj/__init__          2      0   100%
myproj/myproj          257     13    94%
myproj/feature4286      94      7    92%
----------------------------------------
TOTAL                  353     20    94%

Distributed Testing: Each

Distributed testing with dist mode set to each will report on the combined coverage of all slaves. Since each slave is running all tests this allows generating a combined coverage report for multiple environments.

Running distributed testing with dist mode set to each:

py.test --cov myproj --dist each
        --tx popen//chdir=/tmp/testenv3//python=/usr/local/python27/bin/python
        --tx ssh=memedough@host2//chdir=/tmp/testenv4//python=/tmp/env2/bin/python
        --rsyncdir myproj --rsyncdir tests --rsync examples
        tests/

Shows a terminal report:

---------------------------------------- coverage ----------------------------------------
                          platform linux2, python 2.6.5-final-0
                          platform linux2, python 2.7.0-final-0
Name                 Stmts   Miss  Cover
----------------------------------------
myproj/__init__          2      0   100%
myproj/myproj          257     13    94%
myproj/feature4286      94      7    92%
----------------------------------------
TOTAL                  353     20    94%

Reporting

It is possible to generate any combination of the reports for a single test run.

The available reports are terminal (with or without missing line numbers shown), HTML, XML and annotated source code.

The terminal report without line numbers (default):

py.test --cov-report term --cov myproj tests/

-------------------- coverage: platform linux2, python 2.6.4-final-0 ---------------------
Name                 Stmts   Miss  Cover
----------------------------------------
myproj/__init__          2      0   100%
myproj/myproj          257     13    94%
myproj/feature4286      94      7    92%
----------------------------------------
TOTAL                  353     20    94%

The terminal report with line numbers:

py.test --cov-report term-missing --cov myproj tests/

-------------------- coverage: platform linux2, python 2.6.4-final-0 ---------------------
Name                 Stmts   Miss  Cover   Missing
--------------------------------------------------
myproj/__init__          2      0   100%
myproj/myproj          257     13    94%   24-26, 99, 149, 233-236, 297-298, 369-370
myproj/feature4286      94      7    92%   183-188, 197
--------------------------------------------------
TOTAL                  353     20    94%

The remaining three reports output to files without showing anything on the terminal (useful for when the output is going to a continuous integration server):

py.test --cov-report html
        --cov-report xml
        --cov-report annotate
        --cov myproj tests/

Coverage Data File

The data file is erased at the beginning of testing to ensure clean data for each test run.

The data file is left at the end of testing so that it is possible to use normal coverage tools to examine it.

Limitations

For distributed testing the slaves must have the pytest-cov package installed. This is needed since the plugin must be registered through setuptools / distribute for pytest to start the plugin on the slave.

For subprocess measurement environment variables must make it from the main process to the subprocess. The python used by the subprocess must have pytest-cov installed. The subprocess must do normal site initialisation so that the environment variables can be detected and coverage started.

Acknowledgements

Whilst this plugin has been built fresh from the ground up it has been influenced by the work done on pytest-coverage (Ross Lawley, James Mills, Holger Krekel) and nose-cover (Jason Pellerin) which are other coverage plugins.

Ned Batchelder for coverage and its ability to combine the coverage results of parallel runs.

Holger Krekel for pytest with its distributed testing support.

Jason Pellerin for nose.

Michael Foord for unittest2.

No doubt others have contributed to these tools as well.

Tip: Filter by directory path e.g. /media app.js to search for public/media/app.js.
Tip: Use camelCasing e.g. ProjME to search for ProjectModifiedEvent.java.
Tip: Filter by extension type e.g. /repo .js to search for all .js files in the /repo directory.
Tip: Separate your search with spaces e.g. /ssh pom.xml to search for src/ssh/pom.xml.
Tip: Use ↑ and ↓ arrow keys to navigate and return to view the file.
Tip: You can also navigate files with Ctrl+j (next) and Ctrl+k (previous) and view the file with Ctrl+o.
Tip: You can also navigate files with Alt+j (next) and Alt+k (previous) and view the file with Alt+o.