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I'd like to add some custom assert methods to a TestCase. As a simple example, I've just put one inside the test class below. It works as expected, but when the output is generated the traceback includes the custom assert in the output.
What is the step necessary to make it behave like assertEqual()? The code for assertEqual is in TestCase, but the actual line that raises the assertion does not appear in the traceback. What do I need to do to make test_something2's output look more like test_something1's?
import unittest
class TestCustomAssert(unittest.TestCase):
def assertSomething(self, s):
self.assertEqual(s, 'something')
def test_something1(self):
self.assertEqual('foo', 'something')
def test_something2(self):
self.assertSomething('foo')
if __name__ == '__main__':
unittest.main()
Output
python3 custom_assert.py
FF
======================================================================
FAIL: test_something1 (__main__.TestCustomAssert)
----------------------------------------------------------------------
Traceback (most recent call last):
File "custom_assert.py", line 8, in test_something1
self.assertEqual('foo', 'something')
AssertionError: 'foo' != 'something'
- foo
+ something
======================================================================
FAIL: test_something2 (__main__.TestCustomAssert)
----------------------------------------------------------------------
Traceback (most recent call last):
File "custom_assert.py", line 10, in test_something2
self.assertSomething('foo')
File "custom_assert.py", line 6, in assertSomething
self.assertEqual(s, 'something')
AssertionError: 'foo' != 'something'
- foo
+ something
----------------------------------------------------------------------
Ran 2 tests in 0.000s
FAILED (failures=2)
505
Python Unittest Assert Methods. Now, let’s take a look at what methods we can call within Unit testing with Python: assertEqual()- Tests that the two arguments are equal in value. assertNotEqual()- Tests that the two arguments are unequal in value. assertTrue()- Tests that the argument has a Boolean value of True.
Moreover, we saw Python Unittest example and working. Also, we discussed Python Unit Testing frameworks and test case example with Python Unittest assert. We hope you can run your own tests for your code. In this tutorial, we saw how to do that with the Python Unittest and pytest modules.
Python Unittest Assert Methods Now, let’s take a look at what methods we can call within Unit testing with Python: assertEqual ()- Tests that the two arguments are equal in value. assertNotEqual ()- Tests that the two arguments are unequal in value.
The TestCase class of the unittest module provides you with a large number of assert methods to test. The following table shows the most commonly used assert methods: The following assert methods check the exceptions, warnings, and log messages: The following table shows the assert methods that perform more specific checks:
unittest doesn't print tracebacks from frames that have __unittest=True in their globals.
From unittest.result:
def _is_relevant_tb_level(self, tb):
return '__unittest' in tb.tb_frame.f_globals
So, if you make a helper module, you can emulate that behavior:
helper.py:
__unittest = True
def assert_stuff(s):
assert s == 'something', "%s is not something" % s
Now you can call this helper from your test case.
I guess that one could make a very neat decorator that make such magic more automatic without a helper module but IMHO you shouldn't make effort to reduce the traceback anyway.
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