Add input validation of directory paths given to satip

[jsbaasi]

…ries

Pull Request

Description

This change adds a function to utils.py that checks whether a provided path leads to a directory or just a file

The aforementioned function is then added to the top of app.py to check whether save_dir and/or save_dir_native are valid paths

I want to add this change because this will save resources in case you input a bad path. Otherwise the script proceeds to make expensive API calls to EUMETSAT etc. to then fail at the very end when it tries pushing files to the provided save_dir and/or save_dir_native paths.

This has not been put on the issues page

How Has This Been Tested?

The following list shows the 3 save_dir paths that been given as arguments and their results after this PR's changes:

1. A save_dir path that leads to a directory, satip continues executing
2. A save_dir path that leads to a file, satip logs the error and halts execution
3. A save_dir path that doesn't lead to a file or directory, satip logs the error and halts execution

Checklist:

• My code follows OCF's coding style guidelines
• I have performed a self-review of my own code
• I have made corresponding changes to the documentation
• I have added tests that prove my fix is effective or that my feature works
• I have checked my code and corrected any misspellings

[jsbaasi]

Apologies, the name of the branch does not detail what this PR does!

[peterdudfield]

@all-contributors please add @jsbaasi for code

[allcontributors]

@peterdudfield

I've put up a pull request to add @jsbaasi! 🎉