Message should be function and added test cases for the coverage as well

[antsmartian]

What: Jest message should be a function, we have returned a string, so in case of failure, the API is breaking.

Why:

How: Moved them to functions and wrote coverage test cases for them as well.

Checklist:

• Documentation
• Tests
• Ready to be merged
• Added myself to contributors table

[antsmartian]

@kentcdodds Before I merge this, I wanted to check the test cases I have added is mainly for coverage. Not sure element-queries.js is the right place to put. Yes, I have left the comment, but still want to cross check with you, if this is the right place to do so.

[codecov]

Codecov Report

Merging #32 into master will not change coverage.
The diff coverage is 100%.

@@          Coverage Diff          @@
##           master    #32   +/-   ##
=====================================
  Coverage     100%   100%           
=====================================
  Files           5      5           
  Lines          81     85    +4     
  Branches       19     19           
=====================================
+ Hits           81     85    +4

Impacted Files	Coverage Δ
src/jest-extensions.js	100% <100%> (ø)	⬆️

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[kentcdodds]

This looks fine. Thanks!

[kentcdodds]

Remember that if you merge things yourself (generally I'd prefer to review PRs first) that you should use the Squash and Merge feature and that the commit message you set it to follows the convention. See other/MAINTAINING.md for more info :)

Thanks!

[antsmartian]

@kentcdodds Yes, sure. Will mostly give it for a review though. Thanks for merging it.