Is this a bug report?

Yes

Can you also reproduce the problem with npm 4.x?

Yes

Which terms did you search for in User Guide?

test jest import require undefined

Environment

1. npm ls react-scripts-ts (if you haven’t ejected): 2.16.0
2. node -v: v9.7.1
3. npm -v: 4.6.1 (also 6.1.0)
4. yarn --version (if you use Yarn): 1.5.1
5. npm ls react-scripts-ts (if you haven’t ejected): 2.16.0

Then, specify:

1. Operating system: macOS Sierra 10.12.4
2. Browser and version (if relevant): not relevant, the problem is when running tests

Steps to Reproduce

1. create an app as normal and run tests

create-react-app my-app --scripts-version=react-scripts-tscd my-appgit init .yarnyarn test

2. add lodash as a dependency and run tests

yarn add lodash

3. importlodash inApp.jsx and try to call a function on it

import_from'lodash';constfoo=_.join(['f','oo']);

4. Run tests.

yarnyarn test

Expected Behavior

Test should pass.

Actual Behavior

Test suite fails to run:

TypeError: Cannot read property 'join' of undefined

Reproducible Demo

https://github.com/bagilevi/cra-ts-import

Relevant diff:
bagilevi/cra-ts-import@3b986a0

Notes

If I useconst _ = require('lodash') the tests pass, but thenyarn start says "require statement not part of an import statement".

If I tryimport _ = require('lodash'), I get "Import assignment cannot be used when targeting ECMAScript modules. Consider using 'import * as ns from "mod"', 'import {a} from "mod"', 'import d from "mod"', or another module format instead.".

If I renamefoo.ts tofoo.js, the test passes, so the problem seems to be TypeScript-related.

I had the same issue trying to importpouchdb, so it's not justlodash, and they both work in the browser.

Any advice would be appreciated, I just recently started using TypeScript. Thank you.