respect peer dependencies

lib/index.js

@@ -145,7 +145,11 @@ async function analyzeProjectDependencies(options, pkgData, pkgFile) {
   print(options, '\nOptions:', 'verbose')
   print(options, sortOptions(options), 'verbose')
 
-  const [upgraded, latest] = await vm.upgradePackageDefinitions(current, options)
+  const peerDependencies = getPeerDependencies(current, options)
+  print(options, '\nPeerDependencies:', 'verbose')
+  print(options, peerDependencies, 'verbose')
+
+  const [upgraded, latest] = await vm.upgradePackageDefinitions(current, { ...options, peerDependencies })
 
   print(options, '\nFetched:', 'verbose')
   print(options, latest, 'verbose')
@@ -224,6 +228,32 @@ async function analyzeProjectDependencies(options, pkgData, pkgFile) {
   return output
 }
 
+/** Get peer dependencies from installed packages */
+function getPeerDependencies(current, options) {
+  const basePath = options.cwd || './'
+  return Object.keys(current).map(pkgName => {
+    const path = basePath + 'node_modules/' + pkgName + '/package.json'
+    try {
+      const pkgData = fs.readFileSync(path)
+      const pkg = jph.parse(pkgData)
+      return vm.getCurrentDependencies(pkg, { dep: 'peer', filter: options.filter, reject: options.reject })
+    }
+    catch (e) {
+      print(options, 'Could not read peer dependencies for package ' + pkgName + '. Is this package installed?', 'warn')
+      return {}
+    }
+  }).reduce((acc, peers) => {
+    Object.entries(peers).forEach(([pkgName, version]) => {
+      if (acc[pkgName] === undefined) {
+        acc[pkgName] = []
+      }
+      // eslint-disable-next-line fp/no-mutating-methods
+      acc[pkgName].push(version)
+    })
+    return acc
+  }, {})
+}
+
 //
 // Program
 //
@@ -535,4 +565,4 @@ function getNcurc({ configFileName, configFilePath, packageFile } = {}) {
   return result ? { ...result, args } : null
 }
 
-module.exports = { run, getNcurc, ...vm }
+module.exports = { run, getNcurc, getPeerDependencies, ...vm }

lib/package-managers/npm.js

@@ -168,12 +168,27 @@ function satisfiesNodeEngine(versionResult, nodeEngine) {
   return versionNodeEngine && semver.satisfies(minVersion, versionNodeEngine)
 }
 
+/**
+ * Returns true if the peer dependencies requirement is satisfied or not specified for a given package version.
+ *
+ * @param versionResult     Version object returned by pacote.packument.
+ * @param peerDependencies  The list of peer dependencies.
+ * @returns                 True if the peer dependencies are satisfied or not specified.
+ */
+function satisfiesPeerDependencies(versionResult, peerDependencies) {
+  if (!peerDependencies) return true
+  const pkgPeerDependencies = peerDependencies[versionResult.name]
+  if (!pkgPeerDependencies) return true
+  return pkgPeerDependencies.every(v => semver.satisfies(versionResult.version, v))
+}
+
 /** Returns a composite predicate that filters out deprecated, prerelease, and node engine incompatibilies from version objects returns by pacote.packument. */
 function filterPredicate(options) {
   return _.overEvery([
     options.deprecated ? null : o => !o.deprecated,
     options.pre ? null : o => !versionUtil.isPre(o.version),
     options.enginesNode ? o => satisfiesNodeEngine(o, options.enginesNode) : null,
+    options.peerDependencies ? o => satisfiesPeerDependencies(o, options.peerDependencies) : null,
   ])
 }