Make ErrorsSpec use generated types and constructors names

[carbolymer]

Description

All important changes are in ErrorSpec modules. Other modified haskell source files contain Data instances required for using derived types', modules' and constructors' names.

Changelog

- description: |
    Add `Eq` and `Data` instances to various error types
  compatibility: compatible
  type: feature

Checklist

• Commit sequence broadly makes sense and commits have useful messages
• New tests are added if needed and existing tests are updated. These may include:
  • golden tests
  • property tests
  • roundtrip tests
  • integration tests
    See Runnings tests for more details
• Any changes are noted in the CHANGELOG.md for affected package
• The version bounds in .cabal files are updated
• CI passes. See note on CI. The following CI checks are required:
  • Code is linted with hlint. See .github/workflows/check-hlint.yml to get the hlint version
  • Code is formatted with stylish-haskell. See .github/workflows/stylish-haskell.yml to get the stylish-haskell version
  • Code builds on Linux, MacOS and Windows for ghc-8.10.7 and ghc-9.2.7
• Self-reviewed the diff

Note on CI

If your PR is from a fork, the necessary CI jobs won't trigger automatically for security reasons.
You will need to get someone with write privileges. Please contact IOG node developers to do this
for you.

[carbolymer]

There was a typo with file name which went unnoticed. The golden file name didn't match the constructor name. Hopefully it will be harder to make new ones.

[carbolymer]

An escape hatch when adding of Data instance gets impossible (like when we embed TypeRep in our error data types) or requires significant multi-package changes and outweights the benefits here.

[Jimbo4350]

Add your comment to the code 👍

[newhoggy]

I think it would be useful to use type applications here and elsewhere so the type name is in the test code. For example:

testAllErrorMessages @InputDecodeError

[Jimbo4350]

LGTM

[Jimbo4350]

Add your comment to the code 👍

[Jimbo4350]

Left over comment?

[carbolymer]

That's a leftover from original change, that we want to eventually test this case as well, but we can't because we don't have access to data constructors of PastHorizon or its fields' types' constructors and we need to expose a dummy value for such purposes.

[Jimbo4350]

Ideally we want to check that we have covered all of the constructors. I suggest the following (can be a follow up PR):

diff --git a/cardano-api/golden/Test/Golden/ErrorsSpec.hs b/cardano-api/golden/Test/Golden/ErrorsSpec.hs
index 036fe5db0..d6c1d4149 100644
--- a/cardano-api/golden/Test/Golden/ErrorsSpec.hs
+++ b/cardano-api/golden/Test/Golden/ErrorsSpec.hs
@@ -237,11 +237,16 @@ spec = describe "Test.Golden.Errors" $ do
   testAllErrorMessages @TxMetadataRangeError
     [ TxMetadataTextTooLong 0
     , TxMetadataBytesTooLong 0
-    , TxMetadataNumberOutOfRange 0
+   -- , TxMetadataNumberOutOfRange 0
     ]
 
+countDataConstructors :: Data a => a -> Int
+countDataConstructors = length . dataTypeConstrs . dataTypeOf
+
 testAllErrorMessages :: forall a. (HasCallStack, Data a, Error a) => [a] -> Spec
 testAllErrorMessages errs = withFrozenCallStack $ do
+  it "All data constructors covered"  $ do
+    length errs `shouldBe`countDataConstructors (head errs)
   let typeName = show $ typeRep (Proxy @a)
   describe typeName $
     mapM_ testErrorMessage errs

When you run the golden test suite:

...
  ✓ <interactive> passed 1 test.
      TxMetadataRangeError [✔]
    All data constructors covered [✘]
    TxMetadataRangeError
  ✓ <interactive> passed 1 test.
      TxMetadataTextTooLong [✔]
  ✓ <interactive> passed 1 test.
      TxMetadataBytesTooLong [✔]

Failures:

  1) Test.Golden.Errors.Test.Golden.Errors All data constructors covered
       expected: 3
        but got: 2

  To rerun use: --match "/Test.Golden.Errors/Test.Golden.Errors/All data constructors covered/"

You should probably pattern match on the empty list and fail in that case so we can "safely" use head or something similar.