inst/tdda/referencetest/examples/README.md

In noamross/rexr: Wrapper Rexpy Regular Exression Finder Python Module

Examples of using tdda.refererencetest.

To step through these examples, you should first take a copy of the entire examples subdirectory, and put it somewhere else. You'll be making modifications to it, to see the affect of change, and you don't want to be modifying the originals.

Scenario:

You have a python module called `generators.py`, which is responsible
for generating some HTML.

Testing that it's generated the correct HTML isn't hugely easy just
using the standard unit-testing tools on their own. You're continually
making updates to the generator code, and some of these updates will
change the output in ways that don't really matter; updating version
numbers, etc, shouldn't cause tests to stop working, but other changes
do need to be checked.

This examples directory contains the generators.py file, and also a unit-test module, for testing it using tdda.referencetest. In fact there are two test modules - one using the standard unittest framework, and the other using the www.pytest.org pytest framework.

Step 1:

Take a *copy* of the entire examples directory, if you haven't already
done so. All subsequent steps should be carried out in that copy, not
in the original source.

Step 2:

Run the tests using the initial unmodified version of generators.py.

That's either:

    python unittest/test_using_referencetestcase.py

or:

    pytest pytest/test_using_referencepytest.py

The tests should all pass.

Step 3:

Make a substantive change to the generation code in the generate_string
function in `generators.py` to change the HTML output. See doc strings
inside to see how to make the tests fail.

The test should then fail and suggest a diff command to run
to see the difference.

Rerun with

    python test_using_referencetestcase.py -W

or:

    pytest pytest/test_using_referencepytest.py --W

and it will re-write the reference output to match your modified
results. The files in the `reference` subdirectory will have changed
to reflect your changes to the generators.

Running the tests should now pass again.

Step 4:

Make a non-substantive change (such as changing the version numbers)
in generators.py, and run the tests again (without the -W option; you're
wanting to just run  the tests, not regenenerate the expected results).

They should all still pass.

noamross/rexr documentation built on May 23, 2019, 9:30 p.m.