Add tests for missing git-view cases

[Tyriar]

As mentioned in #107, there are tests missing for the view and tooltip for:

• <num> commit(s) ahead <branch>
• <num> commit(s) behind <branch>
• <num> line(s) deleted
• <num> line(s) added and <num> line(s) deleted

[gitjeff05]

I'd like to add these tests. Can anyone provide any guidance on how to setup/modify the git repos in the spec/fixtures folder?

I can create a file and remove text without a problem. But I need a file that already exists in the repo with 2+ lines to remove. There is a fixtures/git/ahead-behind-repo.git, a fixtures/git/no-ahead-behind-repo.git, a fixtures/git/master.git and a working-dir repo. I'm a little unsure of what these are. Are they submodules? I can probably figure it out but wanted to check.

[50Wliu]

/cc @as-cii I noticed that you added a fixture to this repo before, maybe you can point @gitjeff05 along the right path?