Python GUI Programming with Tkinter

Testing file reading in get_all_records()

To see how we use these, let's start a test for the get_all_records() method as follows:

    @mock.patch('abq_data_entry.models.os.path.exists')
    def test_get_all_records(self, mock_exists):
        mock_exists.return_value = True

Since our filenames don't actually exist, we're using the decorator version of patch to patch os.path.exists with a mock function that always returns True. We can later change the return_value value if we want to test a scenario where the file doesn't exist.

To run the get_all_records() method, we'll use the context manager form of patch() as follows:

        with mock.patch('abq_data_entry.models.open', self.file1_open):
            records = self.model1.get_all_records()

Any call to open() inside the ...