Edit Item Espresso tests and Add method to mock Items for Firestore test users

[owencooke]

Describe your changes

This PR accomplishes the following:

• adds Espresso tests for the Edit Item page
• adds a method for creating a test item in the auto-generated Firebase test user's items
• replaces waitForView with a more general waitFor method, to prevent tests failing due to slow Firebase updates

Issue ticket number and link

This PR addresses: #14

Checklist before requesting a review

• I have performed a self-review of my code
• Necessary java docs are present
• Necessary UML diagrams are created
• Necessary tests are written

[owencooke]

@ldbonkowski here's the method to mock an item in Firebase. Lemme know ur thoughts

[ldbonkowski]

Not sure why things are failing on the runners, provided you can pass the checks everything looks good to me

[owencooke]

@ldbonkowski texts go green 🟢.

A re-review would be lovely. I've decided to change waitForView to just a general waitFor that takes a lambda function and tries running it multiple times within a 10s timeout.

This way we can just pass any Espresso statement(s) we like into this method, when we know there's a chance the Firebase updates might be slow.

[ldbonkowski]

LGTM!

[MatthewNeufeld]

Good stuff @owencooke. Just don't forget UML diagrams :)