Add FXIOS-9680 [Unit Tests] Configure store to use var for testing builds

[cyndichin]

📜 Tickets

Jira ticket
Github issue

💡 Description

Context
The store was a global constant that could not be mocked for unit testing. This causes testing issues especially within the middlewares. This PR allows us to overwrite the store and be able to verify logic such as a dispatch of an action or validating state in the store.

Summary

• Added another build configuration called Fennec_Testing that duplicates the Fennec build, and adds an additional flag called TESTING under Custom Flags in the Build settings. This flag can be used to determine which code path to run. We want to have a var store instead of the let store in the testing case.
• Also needed to add the flag under SWIFT_ACTIVE_COMPILATION_CONDITIONS
• Updated the Fennec Scheme to use the Fennec_Testing build configuration when running tests
• Change store to be a variable for testing build
• Updated MicrosurveyMiddlewareTests to override the store

📝 Checklist

You have to check all boxes before merging

• Filled in the above information (tickets numbers and description of your work)
• Updated the PR name to follow our PR naming guidelines
• Wrote unit tests and/or ensured the tests suite is passing
• When working on UI, I checked and implemented accessibility (minimum Dynamic Text and VoiceOver)
• If needed, I updated documentation / comments for complex code and public methods
• If needed, added a backport comment (example @Mergifyio backport release/v120)

Screenshots

Compile errors example:

[cyndichin]

@clarmso Bitrise is failing, we are thinking this is because we are using the Fennec configuration. Could we update the configuration to use Fennec_Testing instead for this PR + future PRs if this decide to land?

cc: @FilippoZazzeroni

[mobiletest-ci-bot]

	Messages
📖	Project coverage: 31.24%
📖	Edited 6 files
📖	Created 1 files

Client.app: Coverage: 29.75

File	Coverage
AppState.swift	100.0%	✅

Generated by 🚫 Danger Swift against 368fee1

[cyndichin]

@FilippoZazzeroni It's passing, I'm crying with happy tears~ 🥳

[FilippoZazzeroni]

It looks good to me, i don't know only for later tests, if we want to add an Utility class to make a custom store and to restore it to default.

[cyndichin]

thanks @FilippoZazzeroni! Yes, you're right, I agree. I created a separate ticket for this though since I prefer to break up work in smaller chunks: https://mozilla-hub.atlassian.net/browse/FXIOS-10094

I'll probably also get the teams input on the best way to go about this since want to make sure that its clear down the row that this is something we need to do for testing.

[FilippoZazzeroni]

Perfect thank you Cyndi, yes that is top.

[cyndichin]

Discussed that the setup and teardown of store will be cleaned up in a future PR and that work will go in FXIOS-10094 as we think about a better way to setup and teardown the stores.

[cyndichin]

@isabelrios @clarmso seems like this PR needs a review from your side as well, let me know if any issues! thank you~

[clarmso]

@cyndichin 👍🏼 Let's see how this scheme behaves. If there are any issues, I will let you know.