pytest-incremental: py.test plugin - incremental test runner


pytest-incremental is a py.test plug-in. It analyses your project structure and file modifications between test-runs to modify the order tests are executed and de-select tests. This allows a much faster feedback for interactive test execution.

Check the documentation for more details.

Note that py.test has support to run standard unittest’s and nose’s tests. So even if you don’t use py.test as a test framework you might be able to use it as a test runner.


pytest-incremental is tested on python 2.7 - 3.3-3.4

pip install pytest-incremental


Just pass the parameter --inc when calling from the command line:

$ py.test --inc

You can also enable it by default adding the following line to your pytest.ini:

addopts = --inc

watched packages

By default all modules from within your CWD will be counted as dependencies if imported. In order to limit or extend the watched folders you must use the parameter --inc-path

This can be used in case you want to watch for changes in modules that are in another project. For example if you are testing my_lib and want to check for changes in dependencies from your py3rd package:

$ py.test --inc --inc-path my_lib --inc-path ../py3rd-trunk/py3rd


You can check what are the actual dependencies detected by running the command:

$ py.test --inc-deps

for better visualization you can create a graph file in “dot” format (see graphviz ):

$ py.test --inc-graph

To generate an image:

$ py.test --inc-graph-image

You can also check what are the outdated tests without executing them:

$ py.test --inc-outdated