Testing

[solkaz]

Description

Adds more tests, refactored some parts for maintainability, and refactored action creator tests to use snapshot tests. Updates the default state values to account for snippets that lack all required fields

Motivation and Context

To maintain maintainability

Checklist:

• [x] My code follows the code style of this project.
• [x] I have added tests to cover my changes.
• [x] All new and existing tests passed.

Browsers

• [x] Chrome
• [x] Firefox
• [x] Safari
• [ ] Mobile:
• [ ] Other: