Add unit tests for ignore feature

[fcollonval]

Add unit tests for the ignore feature #705

[fcollonval]

@meeseeksdev backport to 0.11.x

[lumberbot-app]

Owee, I'm MrMeeseeks, Look at me.

There seem to be a conflict, please backport manually. Here are approximate instructions:

1. Checkout backport branch and update it.

$ git checkout 0.11.x
$ git pull

2. Cherry pick the first parent branch of the this PR on top of the older branch:

$ git cherry-pick -m1 7558e2954cf90bc2ceaa480d1c72004d3b01c45d

3. You will likely have some merge/cherry-pick conflict here, fix them and commit:

$ git commit -am 'Backport PR #717: Add unit tests for ignore feature'

4. Push to a named branch :

git push YOURFORK 0.11.x:auto-backport-of-pr-717-on-0.11.x

5. Create a PR against branch 0.11.x, I would have named this PR:

"Backport PR #717 on branch 0.11.x"

And apply the correct labels and milestones.

Congratulation you did some good work ! Hopefully your backport PR will be tested by the continuous integration and merged soon!

If these instruction are inaccurate, feel free to suggest an improvement.