[FIXED] Unit testing in Python: How to get an if-statement to return TRUE to test the lines within the if-statement?

Issue

Python 3.7. I'm trying to unit test the function below:

    def is_json_clean():
        # function for is_json_clean here, returns bool

    def json_function(blob, raw_bucket, lake_bucket):
        data_string = blob.download_as_bytes()
        data = json.loads(data_string)
        if is_json_clean(data) is True:
            raw_bucket.copy_blob(blob, lake_bucket)

I'm pretty new to mock patches, and could use an example here! How could I use mock.patch or something similar to get that if statement with my is_json_clean() function to return True so that I can assert that the copy_blob function was called? I thought I could make a patch like:

@mock.patch.object(imported_module, "is_json_clean", return_value=True)
def test_json_function(mock):
    # rest of the test function 
    # including assert statement for the copy_blob function 

but how then would I insert this into my test to assert my copy_blob function? I know that quite a few unit test-related questions are out there, but I haven't found exactly the answer to my question yet (like I said, I'm pretty new). Any help is appreciated. Thank you!

Solution

Your mocking looks correct, but I don't see the blob, raw_bucket, or lake_bucket args being passed in within your test case. Here's how I would write it, mocking all 3 of those args.

import unittest

from unittest import mock

import imported_module

class MyTest(unittest.TestCase):
    @mock.patch.object(imported_module, "is_json_clean", return_value=True)
    def test_json_function(self, mock_is_json_clean):
        json_blob = '{"mykey": "myvalue"}'
        mock_blob = mock.Mock()
        mock_blob.download_as_bytes.return_value = json_blob
        mock_raw_bucket = mock.Mock()
        mock_lake_bucket = mock.Mock()

        imported_module.json_function(mock_blob, mock_raw_bucket, mock_lake_bucket)

        mock_raw_bucket.copy_blob.assert_called_once_with(mock_blob, mock_lake_bucket)

if __name__ == "__main__":
    unittest.main()

You can see that I pass in a mock_blob and mock the return value of download_as_bytes, as well as passing in the two buckets. From there, I'm able to do an assert on the mock_raw_bucket.copy_blob call. I was able to get this code running and passing here: https://replit.com/@WesH1/TautLiveTelephone#main.py

Answered By - wholevinski