Test suite

Every Python module should have a corresponding unit test in tests/. The tests should be nearly exhaustive, in the sense that it should be unlikely that a good-faith re-implementation of the module would pass the tests but have significant bugs. Obviously, truly exhaustive tests capable of detecting arbitrary (e.g. deliberate) errors would be impractical.

The default set of unit tests that are run must complete very quickly, with no extraneous output, no GUI windows popping up, etc., because these tests are (and should be) run automatically many times each day during active development. All the output from such tests must be checked automatically, with any output generated for the user representing something the user really does have to do something about.

Additional more expensive tests, GUI tests, or those requiring user input or user examination of the output are also encouraged, but all these must be kept separate from the main automated regression tests.

Note that, due to previous oversights, one cannot assume that any existing file has a corresponding test file already. Moreover, existing test files should not be assumed to be exhaustive or even particularly useful; they vary a lot in how comprehensive they are. So please always check the test file when coding, especially when debugging, because it probably needs work too. You can check how well a particular test file covers a particular file by running coverage. Here is an example of checking to see how well topo/tests/testimage.py covers topo/pattern/image.py:

./topographica -c "import topo.tests;t=topo.tests.run_coverage( \   runner_fn=topo.tests.run_named,runner_args=('testimage.py',), \   targets=['topo/pattern/image.py'])"

Unittests and Doctests

Topographica’s test suite supports test cases that use Python’s unittest module or its doctest module. Unittest provides a framework for writing test cases as objects containing a set of test methods plus common initialization and clean-up code. This framework is useful for constructing heavy-duty tests, but can be cumbersome when only a simple set of correctness tests are required. All unittests in modules with names matching the pattern topo/tests/test*.py can be automatically discovered and run by the topographica command topo.tests.run()

Python’s doctest module allows tests to be specified as a sequence of Python expressions to be evaluated, each followed by the expected result of the command. The entire sequence should be formatted like a trace of an interactive python session. For example:

>>> def f(x):
...    return x+1
>>> f(3)
>>> f(2)
>>> f('foo')
Traceback (most recent call last):
  File "", line 1, in ?
  File "", line 2, in f
TypeError: cannot concatenate 'str' and 'int' objects

As long as each command produces the expected output (including any errors), the test passes. See the doctest documentation for details. As with unittest testsuites, all doctest files with names matching topo/tests/test*.txt can be found and run automatically with the function topo.tests.run().

Important notes:

  • To construct a doctest file from an interactive topographica trace, the entire topographica_tXXX prefix must be removed from every line. Lines with the prefix will be ignored.
  • The testrunner used by topo.tests.run() will happily run an empty doctest file and report no errors (since there were no tests). Make sure to manually check new or modified doctest files with doctest.testfile(filename,verbose=True) to make sure that the tests are actually being run before running make tests or topo.tests.run().
  • Topographica does not currently run doctests embedded in code documentation.

Automatic testing

Currently, topographica is periodically checked out, built, and tested on Linux, OS X, and Windows (automatically, using buildbot). The results of these builds and tests can be seen at buildbot.topographica.org.