# pytest-cov /

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pytest_cov
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# pytest-cov

This plugin supports pytest's distributed testing feature in both load and each modes. Of course it also support centralised testing.

It supports pretty much all features offered by the coverage package.

Each test run with coverage activated may produce any combination of the four report types. There is the terminal report output by pytest, annotated source code, HTML and XML reports.

## Installation

This plugin depends on features just added to py and pytest-xdist. Until py 1.2.2 and pytest-xdist 1.2 are released you will need to install the 'tip' development versions from:

http://bitbucket.org/hpk42/py-trunk/downloads/

http://bitbucket.org/hpk42/pytest-xdist/downloads/

## Usage

Running centralised testing:

py.test --cov myproj tests/


Shows a terminal report:

-------------------- coverage: platform linux2, python 2.6.4-final-0 ---------------------
Name                 Stmts   Exec  Cover   Missing
--------------------------------------------------
myproj/__init__          2      2   100%
myproj/myproj          257    244    94%   24-26, 99, 149, 233-236, 297-298, 369-370
myproj/feature4286      94     87    92%   183-188, 197
--------------------------------------------------
TOTAL                  353    333    94%


Distributed testing with dist mode set to load and branch coverage enabled:

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


The results from the slaves will be combined like so:

-------------------- coverage: platform linux2, python 2.6.4-final-0 ---------------------
Name                 Stmts   Exec Branch BrExec  Cover   Missing
----------------------------------------------------------------
myproj/__init__          2      2      0      0   100%
myproj/myproj          257    244     56     50    93%   24-26, 99, 149, 233-236, 297-298, 369-370
myproj/feature4286      94     87     18     13    89%   183-188, 197
----------------------------------------------------------------
TOTAL                  353    333     74     63    92%


Distributed testing in each mode:

py.test --cov myproj --dist=each
--tx=popen//python=/usr/local/python264/bin/python
--tx=popen//python=/usr/local/python265/bin/python
tests/


Will produce a report for each slave:

-------------------- coverage: platform linux2, python 2.6.4-final-0 ---------------------
Name                 Stmts   Exec  Cover   Missing
--------------------------------------------------
myproj/__init__          2      2   100%
myproj/myproj          257    244    94%   24-26, 99, 149, 233-236, 297-298, 369-370
myproj/feature4286      94     87    92%   183-188, 197
--------------------------------------------------
TOTAL                  353    333    94%
-------------------- coverage: platform linux2, python 2.6.5-final-0 ---------------------
Name                 Stmts   Exec  Cover   Missing
--------------------------------------------------
myproj/__init__          2      2   100%
myproj/myproj          257    244    94%   24-26, 99, 149, 233-236, 297-298, 369-370
myproj/feature4286      94     87    92%   183-188, 197
--------------------------------------------------
TOTAL                  353    333    94%


If desired distributed testing in each mode can instead produce a single combined report:

py.test --cov myproj --cov-combine-each --dist=each
--tx=popen//python=/usr/local/python264/bin/python
--tx=popen//python=/usr/local/python265/bin/python
tests/


Which looks like:

---------------------------------------- coverage ----------------------------------------
platform linux2, python 2.6.4-final-0
platform linux2, python 2.6.5-final-0
Name                 Stmts   Exec  Cover   Missing
--------------------------------------------------
myproj/__init__          2      2   100%
myproj/myproj          257    244    94%   24-26, 99, 149, 233-236, 297-298, 369-370
myproj/feature4286      94     87    92%   183-188, 197
--------------------------------------------------
TOTAL                  353    333    94%


## Limitations

Currently for distributed testing the python used by slaves must have pytest-cov installed in order to operate. This is because the plugin must be registered through setuptools / distribute for pytest to start the plugin on the slave. Hopefully this will change in the not to distant future, such that just like pytest-xdist only python and nothing else is required on the slave side.

Currently the coverage rc file is not rsynced to slaves which can result in different behaviour on the slaves. Use command line options for the time being.

This is an initial release developed on python 2.6 and support for other python versions needs to be checked and fixed. Hence for the time being distributed testing in each mode may be a bit limited in usefulness.

## Acknowledgements

Holger Krekel for pytest with its distributed testing support.

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

Whilst this plugin has been built fresh from the ground up to support distributed testing 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 for pytest and nose respectively.

No doubt others have contributed to these tools as well.