Testing code generators piece by piece.

Matching of Haskell source fragments for code generator unit tests.

Goal

Leverage your knowledge of haskell-src-exts for parsing Haskell source files, and checking that they contain prescribed fragments. This is a general problem of functional testing of code generators: One would like to make it modular, but at the same time as close to produced source as possible. I propose that you parse a Haskell output from code generator with haskell-src-exts and then match on the produced file. Matching would be best done using TemplateHaskell. Or you may also use Haskell-src-exts here in quasiquotes. so this could be an independent library that we use to make xml-typelift and json-autotype better.

Milestones

1. Parse input module with haskell-src-exts, and get a list of type declarations, and a list of instance declarations. (Easy)
2. Use haskell-src-exts to get a data structure from quasiquote.
3. Make a matching function out of a data structure returned by quasiquote.
4. Add convenience interface to parse output file with haskell-src-exts and match patterns.
5. Change all identifiers starting with an underbar (like _function) to be variables. Modify matching function accordingly
6. Change all type identifiers starting with an U_ to be variables.
7. Change all class identitifers starting with an U_ to be variables.
8. Make a test suite for xml-typelift using this.

Possible improvements for the future

Not yet clear that we need this last feature for testing:

• Generate variable substitutions from successful match.