Add HTMLCov style reports

[erikreedstrom]

• added task for html report generation
• tests added for report generation
• updated mock lib to allow for context in mocked tests

[parroty]

Thanks, please allow me some time to review, as its relatively large one. It might be on weekend.

[erikreedstrom]

No worries. There's likely room for improvement. Open for suggestions.

[parroty]

Sorry taking time, I'm just trying out.
It's working great and the design seems quite nice too! Is there any base templates?

Some feedbacks are,

• How about having color on covered lines? (ex. green color). I can see line counts, but maybe good to have easier indicator to differentiate them from irrelevant lines.
• It's minor ones, but it seems some warnings are emitted (following).

lib/excoveralls/html.ex:135: warning: function print_string/2 is unused
...
lib/excoveralls/html.ex:6: warning: unused alias Local

[erikreedstrom]

Thanks for the feedback!

There is only this template currently, but it can be modified easily to add the green highlighting. Although this template followed the HTMLCov design, I thought I would add one that matches the Coveralls.io report style as well. Additionally, it should be easy enough to adjust the config to allow for fully custom templates if one desires.

I was rushing this change out so we could use it in-house; it looks like I missed the warnings. I'll clean up the code. It will be a couple days before I can get back to it though😀

[erikreedstrom]

• rebased on upstream/master
• removed code causing warnings
• added highlights for covered lines
• added ability for custom template path to be declared

The custom templates could use some work, but it at least provides the ability, even if not in an elegant way 😜

[parroty]

Thanks, great ones!