jscodeshift's default testing setup is missing some features, so I wrote my own.

For each codemod, we can add a folder in __testfixtures__ with the dasherized codemod name, and this test setup will run that codemod against all of the files contained therein. testName.input.ts will be modded and the result will be compared with testName.output.ts. You can also add testName.info.json with other useful stuff (e.g. config--not set up yet--or expected log output--see e.g. below).

example:

// testName.info.json
{
  "expectedLogs": [
    [
      "warn",
      "oh noes"
    ],
  ]
}