Add ability to compare between fork point

[jonnycaley]

Addresses #4

Adds the ability to compare between the fork point of the current branch.

Added a compareFrom configuration so the user is able to enter the desired behaviour when comparing the current branch changes to either:

• Previous commit
• Fork point commit

I made a CommitShaProvider interface which contains a function which takes the CommandRunner and returns a Sha. I would have preferred to have the CommitShaProvider return a single command without the CommandRunner parameter (as suggested here) but nested commands aren't supported by the ProcessBuilder (e.g.

git merge-base $(git rev-parse --abbrev-ref HEAD) $(git show-branch -a | grep '\*' | grep -v `git rev-parse --abbrev-ref HEAD` | head -n1 | sed 's/.*\[\(.*\)\].*/\1/' | sed 's/[\^~].*//')

) so I opted for the current solution.

[codecov]

Codecov Report

Merging #46 (5fc7d50) into main (54bf063) will increase coverage by 2.09%.
The diff coverage is 66.66%.

@@             Coverage Diff              @@
##               main      #46      +/-   ##
============================================
+ Coverage     44.05%   46.15%   +2.09%     
- Complexity       28       39      +11     
============================================
  Files             8       11       +3     
  Lines           404      429      +25     
  Branches         88       95       +7     
============================================
+ Hits            178      198      +20     
- Misses          197      200       +3     
- Partials         29       31       +2     

Impacted Files	Coverage Δ	Complexity Δ
...in/com/dropbox/affectedmoduledetector/GitClient.kt	10.29% <14.28%> (+1.06%)	0.00 <0.00> (ø)
...x/affectedmoduledetector/AffectedModuleDetector.kt	38.54% <33.33%> (-0.35%)	1.00 <0.00> (ø)
...tedmoduledetector/commitshaproviders/ForkCommit.kt	72.72% <72.72%> (ø)	6.00 <6.00> (?)
...ectedmoduledetector/AffectedModuleConfiguration.kt	100.00% <100.00%> (ø)	11.00 <3.00> (+3.00)
...ledetector/commitshaproviders/CommitShaProvider.kt	100.00% <100.00%> (ø)	0.00 <0.00> (?)
...oduledetector/commitshaproviders/PreviousCommit.kt	100.00% <100.00%> (ø)	2.00 <2.00> (?)

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[digitalbuddha]

Wow thank you for all the hard work! I'll review in the next few days. Doing holiday stuff now

[jonnycaley]

No need to thank, was a pleasure to contribute 😄 Sounds good! Have a merry Christmas! 🎅

[changusmc]

Again, thank you for this PR and especially for increasing code coverage!

I have 1 small request.

[jonnycaley]

I don't have write access to this repo. Is someone able to merge this for me? Or alternatively, grant me write access