Add more tests for methods involving the database

[Stypox]

Checklist

• This issue contains only one bug.
• I am able to reproduce the bug with the latest version.
• I have read and understood the contribution guidelines.
• I made sure that there are no existing issues - open or closed - which I could contribute my information to.
• I have taken the time to fill in all the required details. I understand that the bug report will be dismissed otherwise.

Affected version

Every version, but in particular this issue was opened after #2335

The problem

We should add more tests for methods that query/use the database, after mocking the NewPipeExtractor. These kind of tests would not be too difficult to do (android tests would, instead, I think), but would anyway allow us to ensure things work correctly faster. For example we could start by adding a test for the SubscriptionManager.rememberAllStreams() method introduced in #2335, see #2335 (comment).

[Stypox]

Also e.g. #2758 should be testable

[SydneyDrone]

I would like to work on this issue. I'm new to open source, so can someone walk me through the process ?

[ktprograms]

@SydneyDrone Sure, I'd be glad to.

Do you have experience with Git?

The general process is:

• Fork the repo in GitHub
• Clone your fork
• Create a feature branch
• Make your changes and commit them
• Push the feature branch to your fork
• Make a pull request from your feature branch to NewPipe's dev branch

[SydneyDrone]

@ktprograms Sorry my mistake:(
I have no problem using git, but it's the first time for me to write database tests, so if there is a quickstart maybe I can finish it more quickly.

[Stypox]

@SydneyDrone you could for example copy this other database test into a new file and then make changes based on it: https://github.com/TeamNewPipe/NewPipe/blob/dev/app/src/androidTest/java/org/schabi/newpipe/local/history/HistoryRecordManagerTest.kt

Put the newly created file in the same java package as the file it is supposed to test (just under androidTest/ instead of main/)

[SydneyDrone]

@SydneyDrone you could for example copy this other database test into a new file and then make changes based on it: https://github.com/TeamNewPipe/NewPipe/blob/dev/app/src/androidTest/java/org/schabi/newpipe/local/history/HistoryRecordManagerTest.kt

Put the newly created file in the same java package as the file it is supposed to test (just under androidTest/ instead of main/)

@Stypox Thank you, I'll give it a shot.

[MustkimKhatik]

@SydneyDrone you are working on this issue right now ?

[SydneyDrone]

@MustkimKhatik Yes, I'm currently working on this issue.