Dynamic import support?

• Issue

Because ts-jest overrides module to commonjs in thetsconfig.json no tests can be written with the new dynamic import('./myModule') syntax. You get either 'import' and 'export' may only appear at the top level or a Syntax error.

• Expected behavior

Dynamic imports should work.

• Link to a minimal repo that reproduces this issue

Just type import('./myModule') in your test or implementation. That’s enough.

[christophercurrie]

In case this helps anyone in the future, I got this working by configuring .babelrc to add dynamic import support as indicated in the Jest docs:

{
  "presets": [["env", {"modules": false}]],

  "plugins": ["syntax-dynamic-import"],

  "env": {
    "test": {
      "plugins": ["dynamic-import-node"]
    }
  }
}

Note you may need to run jest --clearCache to clear your Jest cache to get this to work.

If you don’t use babel for your project normally, you will still need to add a .babelrc file and devDependencies on these two plugins just for this use case.

[screendriver]

Maybe we should re-open this issue? At the moment I have to enable allowSyntheticDefaultImports together with the new esModuleInterop and now my tests are failing again because of import() 🤔

What’s really strange: if I transpile my file directly with tsc I can see

case 0: return [4 /*yield*/, Promise.resolve().then(function () { return require('../foo.json'); }

but when I run the test for that Jest complains with

case 0: return [4 /*yield*/, import('../foo.json')];