Tests for runHook

[groenroos]

This PR adds unit tests for the runHook module.

Closes #129.

[codecov]

Codecov Report

Merging #258 (ac5b9f2) into master (62af748) will increase coverage by 0.40%.
The diff coverage is n/a.

❗ Current head ac5b9f2 differs from pull request most recent head 88f2dde. Consider uploading reports for the commit 88f2dde to get more accurate results

@@            Coverage Diff             @@
##           master     #258      +/-   ##
==========================================
+ Coverage   91.41%   91.82%   +0.40%     
==========================================
  Files          35       35              
  Lines        1247     1247              
==========================================
+ Hits         1140     1145       +5     
+ Misses        107      102       -5     

Impacted Files	Coverage Δ
core/runHook.js	100.00% <0.00%> (+38.46%)	⬆️

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 62af748...88f2dde. Read the comment docs.