astTransformers use typescript plugin throw error

[wszgrcy]

🐛 Bug Report

config

 globals: {
    'ts-jest': {
      tsconfig: 'tsconfig.spec.json',
      astTransformers: {
        before: ['./test/util/jest-test-transformer.ts'],
      },
    },
  },

run with error

  ● Test suite failed to run

    Jest encountered an unexpected token

    Jest failed to parse a file. This happens e.g. when your code or its dependencies use non-standard JavaScript syntax, or when Jest is not configured to support such syntax.

    Out of the box Jest supports Babel, which will be used to transform your files into valid JS based on your Babel configuration.

    By default "node_modules" folder is ignored by transformers.

    Here's what you can do:
     • If you are trying to use ECMAScript Modules, see https://jestjs.io/docs/ecmascript-modules for how to enable it.
     • To have some of your "node_modules" files transformed, you can specify a custom "transformIgnorePatterns" in your config.
     • If you need a custom transformation specify a "transform" option in your config.
     • If you simply want to mock your non-JS modules (e.g. binary assets) you can stub them out with the "moduleNameMapper" config option.

    You'll find more details and examples of these config options in the docs:
    https://jestjs.io/docs/configuration
    For information about custom transformations, see:
    https://jestjs.io/docs/code-transformation

    Details:

    /Users/chen/my-project/static-injector/test/util/jest-test-transformer.ts:1
    import { SourceFile, TransformationContext } from 'typescript';
    ^^^^^^

    SyntaxError: Cannot use import statement outside a module

      at resolveTransformerFunc_1 (node_modules/ts-jest/dist/config/config-set.js:223:39)
      at node_modules/ts-jest/dist/config/config-set.js:235:32
          at Array.map (<anonymous>)

when not add transformer, test is work.

To Reproduce

Steps to reproduce the behavior:

Expected behavior

transformer can use with typescript

Link to repo (highly encouraged)

Debug log:

too long.....

envinfo

System:
    OS: mac
    Node version: v14.17.1

Npm packages:
    jest:27.0.6
    ts-jest:27.0.5
    typescript:4.3.5
    babel(optional):none

[ahnpnl]

Would you pls put a reproduce repo? Thanks

[wszgrcy]

Would you pls put a reproduce repo? Thanks

https://github.com/wszgrcy/ts-jest-use-typescript-plugin

[ahnpnl]

The error you get comes from the fact that when loading custom transformers, ts-jest uses require which only accepts js.

The workaround is you compile your transformer by tsc to js and use that js in your jest config for ts-jest, that should work.

[wszgrcy]

The error you get comes from the fact that when loading custom transformers, ts-jest uses require which only accepts js.

The workaround is you compile your transformer by tsc to js and use that js in your jest config for ts-jest, that should work.

But I think ts-jest is use typescript file to test, so transformer should support typescript file
Now I use ts-node to make it work temporary .

require('ts-node').register({transformers});
module.exports = require('./jest-test-transformer');

[ahnpnl]

Ye that way or compile to js should work. ts-jest is a Jest transformer so we only compile what Jest gives to us. In this case, the error wasn’t thrown out at startup step which Jest doesn’t send the transformer file yet.

We never support ts transformer before so it is a feature/bug.