Use and generate mocks for youtube tests

[XiangRongLin]

• I carefully read the contribution guidelines and agree to them.

• I removed some and added some other Ignores.

  • Added Ignores were mostly file encoding problems (i think)

• Some tests are not immediatly compatible, see each commit message

[XiangRongLin]

So any opinions about this?

I think #527 is a good example on why this is necessary. Normally a change like that can be easily merged if the tests pass. But the tests suite failed there. No one knows if it's due to the change or unrelated broken/flaky tests.

[Stypox]

I like this approach, as I said in #482. The only thing that I think could be improved is that you always have to remember to put YoutubeParsingHelper.resetClientVersionAndKey(); in every YouTube test. I would implement this function somewhere instead and call it in the setup method of each test:

void initNewpipeForTest(@Nullable final String mockResourcePath) { // or maybe have the downloader as argument
    YoutubeParsingHelper.resetClientVersionAndKey();
    if (mockResourcePath == null) {
        NewPipe.init(new DownloaderFactory().getDownloader()); // or whatever the signature is
    } else {
        NewPipe.init(new DownloaderFactory().getDownloader(mockResourcePath));
    }
}

[XiangRongLin]

I personally don't see much difference, since one already has to remember to use the DownloaderFactory and not DownloaderTestImpl like one usually does. If it is absolutly needed, i can add it.

Additionally that specific resetting is only needed for Youtube and not the other services. So if someone used that initNewpipeForTest for SoundClound, they would run code completly unrelated and unneeded. If the other services have global state too (haven't checked), which would require a "reset" method, then initNewpipeForTest would just get bloated.

YoutubeParsingHelper.resetClientVersionAndKey() is a quick and dirty solution, since i didn't want to work on the global state in YoutubeParsingHelper while working on this.

[XiangRongLin]

@Stypox Any update on your opinion about YoutubeParsingHelper.resetClientVersionAndKey()

I would like to get this moving

[Stypox]

Sorry, I missed your response above. I didn't think that running code for unrelated services could cause unrelated and misguiding errors, so you are right, it's better to keep things separate. Everything should be well-documented then.

[XiangRongLin]

Well this was more annoying than expected. After running with the recording a few times random tests started to fail. I guess youtube was thinking i was doing a DOS against them...

@Stypox Where do you want the information, that the reset method has to be used? And has it to be part of this PR or can i address it in a seperate one? I would prefer a seperate one.

[Stypox]

@XiangRongLin yes, you can do it in a separate one.

[Stypox]

Looks good to me, I think this can be merged after 0.20.10 is done with. Thank you!