Testify - A Testing Framework

PLEASE NOTE: Yelp is in the process of switching to py.test. We recommend you use it instead of Testify.

Testify is a replacement for Python's unittest module and nose. It is modeled after unittest, and existing unittest classes are fully supported.

However, Testify has features above and beyond unittest:

• Class-level setup and teardown fixture methods, which are run only once for an entire class of test methods.

• A decorator-based approach to fixture methods, enabling features like lazily-evaluated attributes and context managers for tests.

• Enhanced test discovery. Testify can drill down into packages to find test cases (similiar to nose).

• Support for detecting and running test suites, grouped by modules, classes, or individual test methods.

• Pretty test runner output (hooray color!).

• Extensible plugin system for adding additional functionality around reporting.

• Comes complete with other handy testing utilities, including turtle (for mocking), code coverage integration, profiling, and numerous common assertion helpers for easier debugging.

• More Pythonic naming conventions.

Example Test Case

from testify import *

class AdditionTestCase(TestCase):

    @class_setup
    def init_the_variable(self):
        self.variable = 0

    @setup
    def increment_the_variable(self):
        self.variable += 1

    def test_the_variable(self):
        assert_equal(self.variable, 1)

    @suite('disabled', reason='ticket #123, not equal to 2 places')
    def test_broken(self):
        # raises 'AssertionError: 1 !~= 1.01'
        assert_almost_equal(1, 1.01, threshold=2)

    @teardown
    def decrement_the_variable(self):
        self.variable -= 1

    @class_teardown
    def get_rid_of_the_variable(self):
        self.variable = None

if __name__ == "__main__":
    run()

Unittest Compatibility

Testify will discover and run unittests without any code changes, just point it to a directory containing your tests:

$ testify my_unittests/foo_test.py

To take advantage of more advanced Testify features, just replace unittest.TestCase with testify.TestCase!

Fixtures

Testify provides the following fixtures for your enjoyment:

• @setup: Run before each individual test method on the TestCase(that is, all methods that begin with 'test').

• @teardown: Like setup, but run after each test completes (regardless of success or failure).

• @class_setup: Run before a TestCase begins executing its tests. Note that this not a class method; you still have access to the same TestCase instance as your tests.

• @class_teardown: Like class_setup, but run after all tests complete (regardless of success or failure).

• @setup_teardown: A context manager for individual tests, where test execution occurs during the yield. For example:

  @setup_teardown
  def mock_something(self):
      with mock.patch('foo') as foo_mock:
          self.foo_mock = foo_mock
          yield
      # this is where you would do teardown things

• @class_setup_teardown: Like setup_teardown, but all of the TestCase's methods are run when this yields.

• @let: This declares a lazily-evaluated attribute of the TestCase. When accessed, this attribute will be computed and cached for the life of the test (including setup and teardown). For example:

  @let
  def expensive_attribute(self):
    return expensive_function_call()
  
  def test_something(self):
    assert self.expensive_attribute
  
  def test_something_else(self):
    # no expensive call
    assert True

Order of Execution

In pseudo code, Testify follows this schedule when running your tests:

   Run all 'class_setup' methods
   Enter all 'class_setup_teardown' context managers
   For each method beginning with 'test':
       Run all 'setup' methods
       Enter all 'setup_teardown' context managers
           Run the method and record failure or success
       Exit all 'setup_teardown' context managers
       Run all 'teardown' methods
   Exit all 'class_setup_teardown' context managers
   Run all 'class_teardown' methods

...When Subclassing

Your fixtures are just decorated methods, so they can be inherited and overloaded as expected. When you introduce subclasses and mixins into the... mix, things can get a little crazy. For this reason, Testify makes a couple guarantees about how your fixtures are run:

• A subclass's fixture context is always contained within its parent's fixture context (as determined by the usual MRO). That is, fixture context is pushed and popped in FILO order.

• Fixtures of the same type (and defined at the same level in the class heirarchy) will be run in the order they are defined on the class.