peerDepdencies of a used package not considered

[daveisfera]

Bug Description

A package that's only in peerDependencies of a used package is still marked as unused even though it really is used.

Code snippets

Where the dependency is used:

const jsdomGlobal = require('jsdom-global');

Where the dependency is listed in package.json:

{
  "name": "test_depcheck",
  "license": "PUBLIC DOMAIN",
  "dependencies": {
    "jsdom": "~11.11.0",
    "jsdom-global": "~3.0.2"
  }
}

Versions

• node -v: v10.15.2
• npm -v: 6.4.1
• depcheck --version: 0.7.2

Extra info

If you remove jsdom from package.json, then yarn install gives the following error and the code doesn't work:

yarn install v1.13.0
warning package.json: License should be a valid SPDX license expression
warning test_depcheck: License should be a valid SPDX license expression
[1/4] 🔍  Resolving packages...
[2/4] 🚚  Fetching packages...
[3/4] 🔗  Linking dependencies...
warning " > jsdom-global@3.0.2" has unmet peer dependency "jsdom@>=10.0.0".
[4/4] 🔨  Building fresh packages...

success Saved lockfile.
✨  Done in 0.70s.

json output:

{"dependencies":[],"devDependencies":[],"missing":{},"using":{"jsdom-global":["/Users/dlj/temp/index.js"],"jsdom":["/Users/dlj/temp/index.js"]},"invalidFiles":{},"invalidDirs":{}}

[rumpl]

Hey, I see that you created a test module, could you push it on github please?

You talk about devDependencies but in your package.json your deps are in dependencies, also I'm not sure which one is marked as unused, is it jsdom or jsdom-global?

[daveisfera]

There's not anything more to add then what I included in the bug and I just realized that I had a typo in the original submission. I meant to write peerDependencies and accidentally wrote devDependencies. Here's the link to the code that's "causing the problem":
https://github.com/rstacruz/jsdom-global/blob/371c36a2b64a7c2d014260212cc1a22a6bd1de2b/package.json#L24

[rumpl]

Understood, thanks for reporting this, we don’t look at peer dependencies, we should I guess

[rumpl]

I'm going to close this one since we already support and have a test for peer dependencies.

If you still have problems please open a new issue with a reproducible repo.

Thanks

[dave-nm]

The file in the original comment reproduces the issue.

[rumpl]

@dave-nm I just made a test with jsdom and jsdom-global (see here), could you take a look and tell me if this is what you have? The test passes, jsdom is found as a dependency. There must be something else that is blocking depcheck. I am going to need you to tell me more about your setup if you want me to help you.

Cheers.

[rumpl]

Keep in mind that, in order for peer dependencies to work, you need to do a npm install (or yarn or whatever).

If there are no node_modules where depcheck can read your depency package.json then depcheck can't read and check your peer dependencies.

[daveisfera]

You're right. The issue was that my node_modules wasn't up to date and so the necessary peerDependencies info wasn't there.

[rumpl]

Nice!

Thanks for updating the issue ^^

[daveisfera]

I just realized what the actual problem is. We're using yarn workspaces, so the package.json of the peer dependency is in the node_modules in the parent directory and depcheck isn't loading that info and that's why it's warning about an unused dependency that really is used.

[robross0606]

This still appears to be a problem. My project has a peer dependency on prom-client:

npm WARN prometheus-gc-stats@0.5.1 requires a peer of prom-client@>= 10 < 12 but none is installed. You must install peer dependencies yourself.

However, depcheck lists it as unused after installation:

C:\Code\code>depcheck --version
1.4.0

C:\Code\code>depcheck
Unused dependencies
* prom-client

[rumpl]

@robross0606 could you open a new issue and provide a repository reproducing this error please?