[TS template] Production build fails if test-specific dependencies are not installed.

[dylnclrk]

Hello, I'm trying to reduce the number of packages installed during production builds. One way I've done this before is by splitting non-build dependencies (e.g. test-only dependencies) into devDependencies, and then running yarn install --production during builds.

This used to work with react-scrips v4, but w/ react-scrips v5 I see an error when I try to build. Also, note: this is a problem with the TS template, so I'm guessing that some default behavior changed for how TS compilation works from 4=>5.

---

To reproduce:

1. npx create-react-app test-app --template typescript
2. Open package.json and move @testing-library/react into the devDependencies
3. Get rid of node modules (rm -rf node_modules) and run yarn install --production
4. Run yarn run build
5. See the error

yarn run v1.22.17
$ react-scripts build
Creating an optimized production build...
Failed to compile.

TS2307: Cannot find module '@testing-library/react' or its corresponding type declarations.
    1 | import React from 'react';
  > 2 | import { render, screen } from '@testing-library/react';
      |                                ^^^^^^^^^^^^^^^^^^^^^^^^
    3 | import App from './App';
    4 |
    5 | test('renders learn react link', () => {


error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.

---

Ideas for workarounds:

• Prod-specific tsconfig that excludes test files. Doesn't seem to be supported: Add a way to specify an alternate tsconfig for production builds #6023
• Any other ideas?

[cannontechnology]

You need to add your test file pattern to the excludes in tsconfig.json. ie:
"exclude": [
"build",
"node_modules",
"./src/**/*.test.tsx",
]