Add unified interface test utils

[sharanry]

#18

Proposes a unified interface testing utilities similar to the ones added by @willtebbutt in JuliaGaussianProcesses/KernelFunctions.jl#159.

[codecov-commenter]

Codecov Report

Merging #19 into master will increase coverage by 5.88%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master      #19      +/-   ##
==========================================
+ Coverage   70.58%   76.47%   +5.88%     
==========================================
  Files           5        5              
  Lines          17       17              
==========================================
+ Hits           12       13       +1     
+ Misses          5        4       -1     

Impacted Files	Coverage Δ
src/likelihoods/gaussian.jl	71.42% <0.00%> (+14.28%)	⬆️

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[willtebbutt]

This is looking good. Just a couple of style-related things.

We also need a patch version bump :)

[sharanry]

We also need a patch version bump :)

Since we haven't registered the package and we aren't making any releases yet, are the patch bumps useful?

Also should we register once this is merged?

[theogf]

Haha no patch bump, I think @willtebbutt just forgot it was not registered! We need to leave it at 0.1.0 or it will not be automatically merged

[willtebbutt]

🤦 @theogf is exactly correct - I keep forgetting that this package isn't registered yet...

[sharanry]

facepalm @theogf is exactly correct - I keep forgetting that this package isn't registered yet...

Me too 😆. Should we merge this and register now that we set up the tests?

[willtebbutt]

Sounds good to me.