Ensure unittest example MyTestCase can be run

[samimakinen-twoday]

Documentation

https://docs.python.org/3/library/unittest.html#organizing-test-code

In the examples test functions create instance of Widget class but there is no import for the class.
It is impossible to write unit tests without knowing how to import the modules you are about to test, so it would be nice to see how it is actually done.

[StanFromIreland]

Do you mean there should be an import X? I don't really see it as too important here, we are not going to provide the source for the hypothetical module anyway.

[picnixz]

I think there are some places where we could add dummy objects. For instance:

class MyTestCase(unittest.TestCase):

    @unittest.skip("demonstrating skipping")
    def test_nothing(self):
        self.fail("shouldn't happen")

    @unittest.skipIf(mylib.__version__ < (1, 3),
                     "not supported in this library version")
    def test_format(self):
        # Tests that work for only a certain version of the library.
        pass

    @unittest.skipUnless(sys.platform.startswith("win"), "requires Windows")
    def test_windows_support(self):
        # windows specific testing code
        pass

    def test_maybe_skipped(self):
        if not external_resource_available():
            self.skipTest("external resource not available")
        # test code that depends on the external resource
        pass

However, we say "This is the output of running the example above in verbose mode:" which is incorrect. Instead, let's replace mylib.__version__ < (1,3) by another check, implement external_resource_available and import sys.

For the Widget test, I don't think we need to add a Widget implementation because it'd be too painful to write IMO. We also don't specify the output and don't say "if your run this, you get that". Note that we already had some E2E test with TestStringMethods but the paragraph using Widget is about organizing the code and focuses on setUp(), tearDown() and execution order.