Add basic tests for the test caching functionality

[rl-gitpod]

Also some minor tidy up.

Note that there is some odd behaviour with main (& this branch) atm.

If you run ./example.sh multiple times it is repeating tests incrementally down to 0. Possibly timestamp related, but I'll take a look post-dinner (or tomorrow)

I'll also look at expanding the cache test functionality i.e. changing a test should trigger a re-test, etc.

[codecov-commenter]

Codecov Report

Merging #20 (bc49af4) into main (69e9e5b) will increase coverage by 5.15%.
The diff coverage is 6.06%.

❗ Current head bc49af4 differs from pull request most recent head ec593c6. Consider uploading reports for the commit ec593c6 to get more accurate results

@@            Coverage Diff            @@
##            main      #20      +/-   ##
=========================================
+ Coverage   6.98%   12.13%   +5.15%     
=========================================
  Files          4        4              
  Lines        859      865       +6     
=========================================
+ Hits          60      105      +45     
+ Misses       792      741      -51     
- Partials       7       19      +12     

Impacted Files	Coverage Δ
pkg/dazzle/combiner.go	0.00% <0.00%> (ø)
pkg/dazzle/build.go	4.52% <4.00%> (+4.52%)	⬆️
pkg/dazzle/registry.go	5.35% <14.28%> (+5.35%)	⬆️
pkg/dazzle/project.go	40.79% <0.00%> (+10.94%)	⬆️

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[csweichel]

Nice one! LGTM

[csweichel]

Suggested change

	type removeOpts struct {
	type removeBaseLayerOpts struct {

[csweichel]

Nice one. We could consider (in a next step after this PR) to mock this interface proper, and make removeBaseLayer use this interface, too.

[rl-gitpod]

next step

+1

mock this interface proper

mock or fake?

make removeBaseLayer use this interface

I was going to look at expanding the testing and it would make sense to take a look at doing it then.