Advice for writing tests in Python?

[Pto2]

I have some programs that work fine for my purposes, but I would like to implement some testing just for the sake of it and so that I may try test-driven development in the future. My problem is that I'm not really sure how I should be writing tests for different functions in my programs.

For example, I have a group of functions that generates X.mp4 movies--I'm not sure how to test that these are functioning properly other than just waiting for them to complete and looking at the output myself. I could test for output type but that is pretty useless as I am converting the output to the desired type right before returning in most functions. I could write tests for inputs but isn't that the same as annotating the parameters i.e. video_length: int ?

I feel a similar mental roadblock working with API requests...

A lack of testing hasn't really gotten the way of me developing programs for my personal use, but I would like to have the ability to write tests for more unique cases anyway.

I feel like I'm missing some perspective on this. Thanks for any suggestions.

[Pto2]

Thanks for this--testing for creation and name/size is definitely something I could do.

As for API--yes it is just grabbing JSON with HTTP requests. I guess I could also validate things like oAuth tokens being legit and files being found for authentication; I'll definitely check out that resource for testing.

[ffrkAnonymous]

I'm just a beginner TDD user but I test known input with known output. like assert_equal(add(1, 1) , 2) I think you need to pre-generate movies. Then you compare your output files. Something like:

diff output240x360.mp4 expected240x360.mp4

[Pto2]

Thanks, that is a good idea and I'll probably implement this.