Mocking Python Class In Unit Test And Verifying An Instance

I'm trying to unit test an SFTP helper class that makes some calls to the pysftp module. I want to mock the actual network calls from pysftp so there are no side effects, and just

Solution 1:

You could configure the mock to return a new mock object with __enter__ and __exit__ methods defined. For example:

@mock.patch.object(
    target=pysftp,
    attribute='Connection',
    autospec=True,
    return_value=mock.Mock(
        spec=pysftp.Connection,
        __enter__=lambda self: self,
        __exit__=lambda *args: None)
)deftest_list_files(self, mock_connection):
    # (contents of test case)

In addition, you may want to use:

mock_connection.return_value.listdir.assert_called_with('/some/files/dir')

instead of:

mock_connection.listdir.assert_called_with('/some/files/dir')

As a side note, you could also replace both uses of assert_called_with in your example with assert_called_once_with.

The end result:

$ python -m unittest test_sftp_helper.TestSFTPHelper.test_list_files
.
----------------------------------------------------------------------
Ran 1 test in 0.017s

OK