146 lines
4.9 KiB
Plaintext
146 lines
4.9 KiB
Plaintext
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parametrizing tests
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=================================================
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py.test allows to easily implement your own custom
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parametrization scheme for tests. Here we provide
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some examples for inspiration and re-use.
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Parametrizing test methods through per-class configuration
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--------------------------------------------------------------
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.. _`unittest parameterizer`: http://code.google.com/p/unittest-ext/source/browse/trunk/params.py
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Here is an example ``pytest_generate_function`` function implementing a
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parametrization scheme similar to Michael Foords `unittest
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parameterizer`_ in a lot less code::
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# content of ./test_parametrize.py
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import pytest
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def pytest_generate_tests(metafunc):
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# called once per each test function
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for funcargs in metafunc.cls.params[metafunc.function.__name__]:
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# schedule a new test function run with applied **funcargs
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metafunc.addcall(funcargs=funcargs)
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class TestClass:
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# a map specifying multiple argument sets for a test method
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params = {
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'test_equals': [dict(a=1, b=2), dict(a=3, b=3), ],
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'test_zerodivision': [dict(a=1, b=0), dict(a=3, b=2)],
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}
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def test_equals(self, a, b):
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assert a == b
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def test_zerodivision(self, a, b):
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pytest.raises(ZeroDivisionError, "a/b")
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Running it means we are two tests for each test functions, using
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the respective settings::
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$ py.test -q
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collecting ... collected 4 items
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F..F
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================================= FAILURES =================================
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_________________________ TestClass.test_equals[0] _________________________
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self = <test_parametrize.TestClass instance at 0x26ef2d8>, a = 1, b = 2
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def test_equals(self, a, b):
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> assert a == b
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E assert 1 == 2
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test_parametrize.py:17: AssertionError
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______________________ TestClass.test_zerodivision[1] ______________________
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self = <test_parametrize.TestClass instance at 0x26fa758>, a = 3, b = 2
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def test_zerodivision(self, a, b):
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> pytest.raises(ZeroDivisionError, "a/b")
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E Failed: DID NOT RAISE
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test_parametrize.py:20: Failed
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2 failed, 2 passed in 0.03 seconds
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Parametrizing test methods through a decorator
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--------------------------------------------------------------
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Modifying the previous example we can also allow decorators
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for parametrizing test methods::
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# content of test_parametrize2.py
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import pytest
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# test support code
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def params(funcarglist):
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def wrapper(function):
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function.funcarglist = funcarglist
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return function
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return wrapper
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def pytest_generate_tests(metafunc):
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for funcargs in getattr(metafunc.function, 'funcarglist', ()):
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metafunc.addcall(funcargs=funcargs)
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# actual test code
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class TestClass:
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@params([dict(a=1, b=2), dict(a=3, b=3), ])
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def test_equals(self, a, b):
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assert a == b
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@params([dict(a=1, b=0), dict(a=3, b=2)])
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def test_zerodivision(self, a, b):
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pytest.raises(ZeroDivisionError, "a/b")
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Running it gives similar results as before::
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$ py.test -q test_parametrize2.py
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collecting ... collected 4 items
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F..F
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================================= FAILURES =================================
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_________________________ TestClass.test_equals[0] _________________________
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self = <test_parametrize2.TestClass instance at 0x1e5e638>, a = 1, b = 2
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@params([dict(a=1, b=2), dict(a=3, b=3), ])
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def test_equals(self, a, b):
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> assert a == b
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E assert 1 == 2
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test_parametrize2.py:19: AssertionError
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______________________ TestClass.test_zerodivision[1] ______________________
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self = <test_parametrize2.TestClass instance at 0x1e6f560>, a = 3, b = 2
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@params([dict(a=1, b=0), dict(a=3, b=2)])
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def test_zerodivision(self, a, b):
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> pytest.raises(ZeroDivisionError, "a/b")
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E Failed: DID NOT RAISE
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test_parametrize2.py:23: Failed
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2 failed, 2 passed in 0.03 seconds
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checking serialization between Python interpreters
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--------------------------------------------------------------
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Here is a stripped down real-life example of using parametrized
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testing for testing serialization betwee different interpreters.
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We define a ``test_basic_objects`` function which is to be run
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with different sets of arguments for its three arguments::
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* ``python1``: first python interpreter
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* ``python2``: second python interpreter
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* ``obj``: object to be dumped from first interpreter and loaded into second interpreter
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.. literalinclude:: multipython.py
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Running it (with Python-2.4 through to Python2.7 installed)::
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. $ py.test -q multipython.py
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collecting ... collected 75 items
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....s....s....s....ssssss....s....s....s....ssssss....s....s....s....ssssss
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48 passed, 27 skipped in 2.74 seconds
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