feat: Adding files exercise

[calvinbrown085]

#482

This adds an example for reading in a file from the filesystem! Please let me know if I can do anything else here!

[AbdouSeck]

Hi @calvinbrown085, thanks for proposing this feature. I am trying to figure out what the learner is supposed to do here. Are you trying to have the learner write the unit test case? If so, then the exercise won't work as written. The learner does not write and update unit tests. They update functions on top of the file, and your unit tests try to check the correctness of said functions.

For instance, in the file file1.rs, what probably want to have is an incomplete function definition at the top. So, this means leaving fn create_file() -> std::io::Result<()> {} incomplete. And then, you want to write unit tests that assert! that the file has been created.

Please feel free to reach out if you wish to discuss this further.

Thanks,
Abdou

[AbdouSeck]

Please my comments above