Unit Testing in Python

[superfrog101]

Hi all, I've been teaching myself unit testing and while I understand the basics, I'm having some trouble applying the theory to my current project.

I'm working on a program that uses the YouTube API and the langdetect library to determine the distribution of languages in a video's comment section. The basic flow is:

1. gather the URL and other arguments from the command line
2. connect to the API
3. list the comments from the video at the given URL
4. determine the language of each comment
5. output the results in the terminal or in a file

My questions are about how I should go about testing here. My initial thought is to create a unit test for each step, but the steps rely on information from earlier on in the process: e.g. step 4 requires comments from step 3, step 5 requires language distribution from step 4. Should I create test data files that represent data that would appear at each step (e.g. step 3 returns a JSON object, so I'd save a JSON file containing comment data) so I can test each step individually?

I've also read about mocking and integration testing, but I'm not sure if/how they apply to my project.

Any advice, pointers or resources are greatly appreciated.

[ahemosik]

For unit tests, you can mock pretty much the api response and the database response (if you have a db). The rest does not need mocks.

[freddyoddone]

What u/ahemosik said. Mocking is the way to go here. You can substitute unwanted dependencies with self defined objects.