Add a means to install package peer dependencies for development / testing

[jshthornton]

Do you want to request a feature or report a bug?
Feature

What is the current behavior?
N/A

What is the expected behavior?
Provide a CLI command yarn install --peer which will install peer dependencies specified in package.json. That way development / testing can use the peers such as react/ng2/grunt.

[jshthornton]

@jpollard-cs I am not referring to adding a package as a peer dependency, I am referring to having a means to install all packages currently listed as peer dependencies.
Otherwise there is not a viable means of developing plugins.

[esutton]

npm install
Would install all packages declared in package.json dependencies section.

yarn add --peer
I expected this to install all packages declared in package.json peerDependencies section.

Is there a way to install a declared packages in peerDependencies?

My use case is development / testing of a react native module.

[oliverjanik]

Here's NPM issue, which they closed: npm/npm#11213

Apparently not important to NPM devs.

[gf3]

+1 this is important for library authors

[nathanhleung]

I already wrote this on the NPM issue, but for Yarn people:

I wrote a cli program install a package's peer dependendencies:

# If you're using npm
npm install -g install-peerdeps

# If you're using yarn
yarn global add install-peerdeps

cd my-project-directory

install-peerdeps <package>[@<version>]

# for example
install-peerdeps @angular/core
# will install all of angular's peerdeps

If you have any problems with it please open an issue on the repo!

[jshthornton]

@nathanhleung, that package appears to install all of your dependencies peer dependencies. Which isn't quite what this ticket is about. This about installing your own package's peer dependencies.

I have fixed it with a package to do that https://www.npmjs.com/package/@team-griffin/install-self-peers

[LyzioOh]

@nathanhleung you rocks.

[nikolakanacki]

Hmm... If one needs dependencies for development / testing, shouldn't one put them under devDependencies? Not trying to drop a bomb or anything...

[avegancafe]

@nikolakanacki Totally see where you're coming from, I think the weirdness is that it'd be both a peer dependency and dev dependency, since you should never force your consumers installing your dev dependencies. I vote making it easy to install peers!

[alexilyaev]

@nikolakanacki If you author a package that relies on another package that the user installs, you don't want it in devDependencies, that may result in a duplicate of that package in a different version., and won't makes sense in some cases...

Use case eslint-find-rules

The package looks up rules available in ESLint that are not configured in your config.
For it to make sense for a user, it needs to check the ESLint package they installed, and not some specific version your package comes with (or latest).
So, it's a peer dependency.

Now if you want to contribute to the project, you want to have ESLint installed in node_modules so you can test your code, without doing some npm-link with a dummy project that installs ESLint.

When the user runs yarn, the system should not install peer deps and warn they're missing (this works).

So... a flag that makes yarn install peer deps if they're not already installed would kindly solve that problem.

Interesting point

• yarn add <package> --peer installs it to node_modules and adds it to package.json
• yarn add <other_package> after that removes the installed package from node_modules

[gaastonsr]

I'm currently following @nikolakanacki model and it seems to work. I agree it can be confusing and I would prefer a yarn install --peer to install dependencies, devDependencies and peerDependencies but this works just as good to me.

[nikolakanacki]

If I'm getting this right @kyleholzinger / @gaastonsr, you're not looking to install peerDependencies in development mode (cd-ed into the repo / package which has peerDependencies, fresh clone, need to develop on those peer deps) but add them to the target project once you install the package which has peer deps?

To clarify: You install eslint-find-rules which complains that you need eslint as a dependency (it's a peerDependency of eslint-find-rules), so now you want an easy way of adding those dependencies in the peer you're working on (current project which depends on eslint-find-rules)? Something like "Resolve and add as new dependencies (modify package.json and yarn.lock) best matched peer dependencies my current dependencies require"?

If this is your point it could be super useful, I thought that you were referring to auto-installing them when developing.

The feature could be introduced for more then pure convenience, for example: multiple dependencies could depend on the same package from the peer target, but require different versions of it - this feature could make the best of it by trying to resolve to a single best-matching target (if possible).

Something to think about definitely.