pytest-regtest 0.2.2

py.test plugin for regression tests

This pytest-plugin allows capturing of output of test functions which can be compared to the captured output from former runs. This is a common technique to start TDD if you have to refactor legacy code which ships without tests.

To install and activate this plugin you have to run:

$ pip install pytest-regtest

from your command line.

This py.test plugin provides a fixture named regtest for recording data by writing to this fixture, which behaves like an output stream:

def test_squares_up_to_ten(regtest):

    result = [i*i for i in range(10)]

    # one way to record output:
    print >> regtest, result

    # alternative method to record output:
    regtest.write("done")

For recording the approved output, you run py.test with the –reset-regtest flag:

$ py.test --reset-regtest

The recorded output is written to text files in the subfolder _regtest_outputs next to your test scripts.

You can reset recorded output of files and functions individually as:

$ py.test --reset-regtest tests/test_00.py
$ py.test --reset-regtest tests/test_00.py::test_squares_up_to_ten

If you want to check that the testing function still produces the same output, you ommit the flag and run you tests as usual:

$ py.test

This shows diffs for the tests failing because the current and recorded output deviate.