Some clean up of contexts

[torfjelde]

Some cleanup of the context implementations:

1. Fixes bug in PrefixContext which doesn't actually work for .~ statements due to implementing the incorrect signature.
2. Removes now-unusued implementations of tilde_*_assume/observe methods for PriorContext and LikelihoodContext + removed their vars field which is also not used any more (this was only used by the logprob macro which was removed in Remove the prob and logprob macros #604 )

[coveralls]

Pull Request Test Coverage Report for Build 11740182612

Details

• 31 of 31 (100.0%) changed or added relevant lines in 4 files are covered.
• 23 unchanged lines in 2 files lost coverage.
• Overall coverage increased (+1.5%) to 83.389%

---

Files with Coverage Reduction	New Missed Lines	%
src/model.jl	3	91.58%
src/threadsafe.jl	20	50.86%

Totals
Change from base Build 11731628292:	1.5%
Covered Lines:	3474
Relevant Lines:	4166

---

💛 - Coveralls

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 83.38%. Comparing base (d6e2147) to head (decaa78).

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #711      +/-   ##
==========================================
+ Coverage   81.90%   83.38%   +1.48%     
==========================================
  Files          30       30              
  Lines        4200     4166      -34     
==========================================
+ Hits         3440     3474      +34     
+ Misses        760      692      -68     

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[penelopeysm]

LGTM as remaining CI errors are known to be due to #702

[torfjelde]

Thanks @penelopeysm !

Fixes bug in PrefixContext which doesn't actually work for .~ statements due to implementing the incorrect signature.

I think we need a way to test this though (as that would have caught the current bug). IMO every context should at be evaluated with both DefaultContext and SamplingContext to ensure that the full tilde-pipeline is implemented.

[torfjelde]

Think this PR is ready for another round of reviews 👍 Added proper testing for the contexts + a test_context function to streamline the testing of a new context a bit more. Also fixed quite a few bugs in the process 😬

[penelopeysm]

Still looks good, save for one question!

[torfjelde]

Thank you @penelopeysm !

[yebai]

A few tests are broken, stopping auto-merging from being completed.