Skip to main content

pytest plugin for regression tests

Project description

pytest-regtest is a pytest-plugin for implementing regression tests. Compared to functional testing a regression test does not test if software produces correct results, instead a regression test checks if software behaves the same way as it did before introduced changes.

More about regression testing at Regression testing is a common technique to get started when refactoring legacy code lacking a test suite.

pytest-regtest allows capturing selected output which then can be compared to the captured output from former runs.

To install and activate this plugin execute:

$ pip install pytest-regtest

pytest-regtest plugin provides a fixture named regtest which can be used as a file handle for recording data:

from __future__ import print_function

def test_squares_up_to_ten(regtest):

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

    # one way to record output:
    print(result, file=regtest)

    # alternative method to record output:

If you run this test script with pytest the first time there is no recorded output for this test function so far and thus the test will fail with a message including a diff:

$ py.test

def test_squares_up_to_ten(regtest):
>       Regression test failed
>       --- is
>       +++ tobe
>       @@ -1,2 +1 @@
>       -[0, 1, 4, 9, 16, 25, 36, 49, 64, 81]
>       -done
>       +

For accepting this output, we run pytest with the –regtest-reset flag:

$ py.test --regtest-reset

Now the next execution of py.test will succeed:

$ py.test

The recorded output was written to files in the subfolder _regtest_outputs next to your test script(s). You might keep this folder under version control.

Other features

Another way to record output is the regtest_redirect fixture:

def test_squares_up_to_ten(regtest_redirect):

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

    with regtest_redirect():
        print result

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

$ py.test --regtest-reset tests/
$ py.test --regtest-reset tests/

To supress the diff and only see the stats use:

$ py.test --regtest-nodiff

To see recorded output during test execution run:

$ py.test --regtest-tee -s

To support testing of the same code on different platforms by default pytest-regtest ignores differences in line breaks when comparing the approved to the actual output. To switch this off use the –regtest-regard-line-endings flag:

$ py.test --regtest-regard-line-endings

Project details

Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Filename, size & hash SHA256 hash help File type Python version Upload date
pytest-regtest-0.15.1.tar.gz (5.4 kB) Copy SHA256 hash SHA256 Source None May 9, 2017

Supported by

Elastic Elastic Search Pingdom Pingdom Monitoring Google Google BigQuery Sentry Sentry Error logging AWS AWS Cloud computing DataDog DataDog Monitoring Fastly Fastly CDN DigiCert DigiCert EV certificate StatusPage StatusPage Status page