Python unittest는 JUnit을 바탕으로 제작된 builtin testing framework이다.
Basic Usage
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| import unittest
class TestSomething(unittest.TestCase):
@classmethod
def setUpClass(cls):
"""
This classmethod is executed only once,
while `setUp` is executed for every test methods.
When this method raises error,
all tests and `tearDownClass` in this class will be skipped.
"""
def setUp(self):
"""
This method is executed before executing test methods.
When this method raises error,
the test and `tearDown` will be skipped.
"""
def tearDown(self):
"""
This method is executed after executing test methods,
regardless of success.
"""
@classmethod
def tearDownClass(cls):
"""
This classmethod is executed only once,
while `tearDown` is executed for every test methods.
"""
def test_something(self):
self.assertEqual('foo'.upper(), 'Foo')
self.assertTrue(2 == 2)
self.assertFalse(2 == 3)
with self.assertRaises(ValueError):
int('h')
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Running Tests
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| python -m unittest [-v] test_module [...] # Run tests in the module
python -m unittest path_to_test/test.py # Module as file
python -m unittest test_module.TestClass # Run tests in the class
python -m unittest test_module.TestClass.test_method # Run single test
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Test Management
Decorator를 이용하여 test의 동작을 control할 수 있다.
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| class TestManagement(unittest.TestCase):
@unittest.skip("reason")
def test_deprecated(self): ...
# or skipUnless
@unittest.skipIf(somelib.__version__.split('.')[0] < '2', "Old dependency version")
def test_somelib(self): ...
@unittest.expectedFailure
def test_must_fail(self):
self.assertEqual(2, 3)
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Async Test
TestCase 대신 IsolatedAsyncioTestCase를 사용하여 coroutine을 test로 만들 수 있다.
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| class AsyncTest(unittest.IsolatedAsyncioTestCase):
async def asyncSetUp(): ...
async def asyncTearDown(): ...
|
Mocking Objects
unittest.mock 모듈의 Mock, MagicMock, AsyncMock, @patch 등을 사용할 수 있다.
MagicMock은 magic method(special method)의 mocking을 지원하고,
AsyncMock은 coroutione의 mocking을 지원한다.
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| # Mock method.__class__ and identity
something.value = Mock(spec=Value)
assert isinstance(something.value, Value)
# Method always returns 3
something.method = Mock(return_value=3)
# Method always raises ValueError
something.method = Mock(side_effect=ValueError())
# Method is equal to f(x) = x+2
something.method = Mock(side_effect=lambda x: x + 2)
# Method behaves like generator
something.method = Mock(side_effect=[5, 4, 3, 2, 1])
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@patch는 테스트 도중 특정 객체를 MagicMock object로 치환하고, 테스트가 끝나면 복원시킨다.
@patch는 치환한 Mock object를 기존 argument 뒤에 붙여주기 때문에 decorator 순서에 유의하자.
만약 클래스의 메소드를 치환하고자 한다면 @patch.object를 사용할 수 있다.
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| def bar(self):
return foo() * foo()
class Foo:
def hello(self): ...
class Test(unittest.TestCase):
@patch("foo")
def test_bar(self, foo: MagicMock):
foo.return_value = 5
self.assertEqual(bar(), 25)
self.assertEqual(foo.call_count, 2)
@patch.object(Foo, "hello")
def test_foo(self, hello: MagicMock): ...
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Mock Assertion
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| mock.assert_called() # Assert that mock object is called at least once
mock.assert_called_with(args) # Assert that mock object is called with given args
mock.assert_called_once() # Assert that mock object is called only once
mock.assert_called_once_with() # Assert that mock object is called only once with given args
mock.assert_not_called() # Assert that mock object is not called
async_mock.assert_awaited() # Assert that mock object is awaited
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