Unmet peer dependency for sinon package in npm

Question

I tried to install sinon via npm: npm install sinon --save-dev

But I got a unmet peer dependency error:

├── UNMET PEER DEPENDENCY sinon@2.3.8
└── sinon-chai@2.8.0 extraneous

npm ERR! peer dep missing: sinon@>=1.4.0 <2, required by sinon-chai@2.8.0

I do not understand why sinon should be <2 as I installed the current version, which is 2.3.8

Answer 1

You have only misunderstood the error message. It's telling you that sinon-chai requires sinon in the range >=1.4.0 <2 . Installing version 2.3.8 does not provide a compatible version to sinon-chai .

You have two choices: either specifically install a version of sinon in the given range; or update sinon-chai to version 2.12.0 , which supports a more recent version range:

"dependencies": {
    "sinon-chai": "^2.12.0",
    "sinon": "^2.3.8",
    ...
}