Revisit dependency pinning

[iansu]

Pinning all of our dependencies causes issues with the preflight check whenever a new version of a nested dependency is released. babel-jest is one example of this. When a new version is released and used by another dependency the preflight check fails until we update our version to match.

We should consider unpinning certain dependencies like babel-jest and updating the preflight check to work with carrot versions like ^24.7.1. It currently only works with exact version numbers.

[ianschmitz]

Here's an example we get a preflight warning in our CI. We noticed this quite a bit the last few days as Jest has released a few new versions in quick succession. Each new release would break CI.

This is an example npm ls babel-jest output when everything works nicely:

test-app@0.1.0 /c/projects/test-app
└─┬ react-scripts@3.0.0-next.b0cbf2ca
  ├── babel-jest@24.5.0
  └─┬ jest@24.5.0
    └─┬ jest-cli@24.5.0
      └─┬ jest-config@24.5.0
        └── babel-jest@24.5.0  deduped

However when a new version of jest comes out, let's say 24.6.0, even though we pinned jest@24.5.0 and babel-jest@24.5.0, jest references jest-cli: ^24.5.0.

What would happen during npm install is we get jest-cli@24.6.0, which brings in jest-config@24.6.0 and babel-jest@24.6.0 which ends up in the root of node_modules, while putting babel-jest@24.5.0 inside node_modules/react-scripts/node_modules/babel-jest, and then when running CRA we get the preflight warning.

[minesaner]

The preflight check folder is <rootDir>/node_modules. Maybe <scriptsVersion>/node_modules should be check first.

[yuchuan1]

Jest 24.8.0 breaks it again.

When I run npx create-react-app someapp and then run yarn start. It gave me the following error.

yarn run v1.15.2
$ react-scripts start

There might be a problem with the project dependency tree.
It is likely not a bug in Create React App, but something you need to fix locally.

The react-scripts package provided by Create React App requires a dependency:

"babel-jest": "24.7.1"

Don't try to install it manually: your package manager does it automatically.
However, a different version of babel-jest was detected higher up in the tree:

/Users/eddiechen/github/someapp/node_modules/babel-jest (version: 24.8.0)

Manually installing incompatible versions is known to cause hard-to-debug issues.

If you would prefer to ignore this check, add SKIP_PREFLIGHT_CHECK=true to an .env file in your project.
That will permanently disable this message but you might encounter other issues.

To fix the dependency tree, try following the steps below in the exact order:

1. Delete package-lock.json (not package.json!) and/or yarn.lock in your project folder.
2. Delete node_modules in your project folder.
3. Remove "babel-jest" from dependencies and/or devDependencies in the package.json file in your project folder.
4. Run npm install or yarn, depending on the package manager you use.

In most cases, this should be enough to fix the problem.
If this has not helped, there are a few other things you can try:

5. If you used npm, install yarn (http://yarnpkg.com/) and repeat the above steps with it instead.
   This may help because npm has known issues with package hoisting which may get resolved in future versions.

6. Check if /Users/eddiechen/github/someapp/node_modules/babel-jest is outside your project directory.
   For example, you might have accidentally installed something in your home folder.

7. Try running npm ls babel-jest in your project folder.
   This will tell you which other package (apart from the expected react-scripts) installed babel-jest.

If nothing else helps, add SKIP_PREFLIGHT_CHECK=true to an .env file in your project.
That would permanently disable this preflight check in case you want to proceed anyway.

P.S. We know this message is long but please read the steps above :-) We hope you find them helpful!

error Command failed with exit code 1.

The error went away after I changed "babel-jest": "24.7.1" to "babel-jest": "^24.7.1" in package.json of create-react-app.

[icyJoseph]

Suffering from the very same issue. Any CRA made this morning fails to start because of 24.8.0 in babel-jest. Same output as @yuchuan1

[abisuq]

add a version resolutions into package.json temporarily

"resolutions": {
    "babel-jest": "24.7.1"
  },

[russellr922]

Ran into same problem today.

[jdarling]

Resolutions didn't work for me. Any other ideas on a work around? I'm using Yarn so that might have something to do with it, but I've tried with npm as well and that just hangs at starting before it finally dies with an allocation failure.

[eddiemonge]

Also getting this with webpack