Add eval coverage

[cb341]

Since a couple years time, simplecov supports eval coverage.

This allows us to also check for branch and line coverage within erb files.
Most importantly views html.erb. I propose we check the eval coverage in new applications by default.

Related PRs:

• https://github.com/renuo/renuo-dashboard/pull/429

[coorasse]

From the last discussion, we should enable grouped coverage.

[cb341]

@coorasse
From the last discussion, we should enable grouped coverage.

Why? I don't see how this relates to the app setup for eval coverage.
I'd enforce 100% line / code coverage regardless of source.

[cb341]

The coverage groups would mainly be relevant in existing projects when we introduce eval.

[coorasse]

I am a bit afraid of being too strict. But you are right! Let's see if that's fine also for others

[cb341]

@coorasse
I am a bit afraid of being too strict. But you are right! Let's see if that's fine also for others

Can't we say the same about the 100% line and branch coverage requirements on ruby files too?

[coorasse]

From my point of. view most of the business logic, which is what I mostly care about stays in rb files. I'd expect the little logic that stays in the views to be more frontend-related, and therefore not that business critical.
One example: checking if the page displays "no results" when there's no results, is not as business critical as everything else, and I'd not like to force the developer to test it but rather leave it to personal judgement.
Once said said, I am one of many seniors engineers here, if somebody has a strong preference in an opposite direction, I am very much open.

[rnestler]

I think since one usually doesn't have much logic in the templates the coverage should be easy to reach. And if not everything is covered it is helpful to know since it can indicate:

• Dead / unreachable code in the template
• Edge cases that were forgotten to test
• To much logic in the templates such that it gets hard to test all edge cases

Only downside is probably a bit longer test run?

[cb341]

I think since one usually doesn't have much logic in the templates the coverage should be easy to reach. And if not everything is covered it is helpful to know since it can indicate:

* Dead / unreachable code in the template

* Edge cases that were forgotten to test

* To much logic in the templates such that it gets hard to test all edge cases

Yes, absolutely.
Too much logic in templates probably indicates that a refactoring via helpers is necessary.
Also without 100% branch coverage in views how can you be certain, that the code doesn't explode.

As I have received the approval and personally think that this change will improve the resiliance of future projects, I am merging this one-liner.