Support different parsers in the test utils

[skovy]

Motivation

jscodeshift now supports TypeScript (and other parsers) via the CLI. The react-codemod package can now support different React codebases.

Changes

In order to use the defineTest helper in testUtils.js with different parsers the defineTest function needs to allow dynamic parsers and look at different extensions (for TypeScript: .ts, .tsx).

The approach used in this PR was to add another parameter testOptions that allows passing in an object with a parser key. The extension then can be inferred from the file being parsed.

I didn't feel great about adding another parameter so I opted for an object so if there are additional config options they can be added to this object rather than adding more arguments and passing many nulls to get to the proper position. I also considered folding testFilePrefix into this object:

{
  testFilePrefix?: string;
  parser?: "flow" | "ts" | "tsx" | ...;
}

However, this would be a breaking change for those using the testUtils. I'm happy to make that change but opted for avoiding the breaking change.

I also originally experiment with reusing the second existing options parameter but that's what get's passed to the transformer and it felt like mixing two unrelated option configs. Open to feedback on this approach. See the proposed pull request in react-codemod for how this helper would be used and the overall motivation for this change: reactjs/react-codemod#228

Testing

• See the new TypeScript sample added (in the sample directory)

[Daniel15]

Seems like a reasonable idea. Could you please rebase?

[skovy]

Thanks for taking a look @Daniel15! This should be ready for another look 👌

[vagusX]

Sorry but I have to ask that when will this feature release to npm? @Daniel15