Regression Test Suite

[ahubers]

What

We want a test suite to run to catch regressions in party-ctrs functionality. A non-comprehensive list of what should be asserted in some form:

Vanilla Party-Ctrs tests

• data Ord a => Tree a = ... should compile.
• ... TODO

Type Family Shenanigans

• Open type families should generate WF constraints in-file.
• Recursive type family instances should have recursive WF constraint instances
• Closed recursive type families should have closed recursive WF constraint instances (these cases are different; closed recursive TFs can have overlap)
• Associated type families should generate open WF constraint
• permutations{implicit, explicit} imports/exports of open TF (cover all 4 cases)
• Closed TFs
• Higher return arities

Some problems

Right now, the hadrian test suite runs on a stage2 compiler, which is way too late in the development flow. Want this to run on stage1 compiler, but that is causing issues for me now (need to resolve).

Some Docs

• https://gitlab.haskell.org/ghc/ghc/-/blob/master/hadrian/doc/testsuite.md