fix: reenable npm link from registry

Being able to npm link a package that is not currently available in the
global space should still be a supported feature, this change puts that
functionality back in place but also improves it by avoiding reify any
package that may already be found in the global directory.

Author: ruyadorno

lib/link.js

@@ -4,6 +4,9 @@ const { readdir } = require('fs')
 const { resolve } = require('path')
 
 const Arborist = require('@npmcli/arborist')
+const npa = require('npm-package-arg')
+const rpj = require('read-package-json-fast')
+const semver = require('semver')
 
 const npm = require('./npm.js')
 const usageUtil = require('./utils/usage.js')
@@ -17,7 +20,7 @@ const completion = (opts, cb) => {
 const usage = usageUtil(
   'link',
   'npm link (in package dir)' +
-  '\nnpm link [<@scope>/]<pkg>'
+  '\nnpm link [<@scope>/]<pkg>[@<version>]'
 )
 
 const cmd = (args, cb) => link(args).then(() => cb()).catch(cb)
@@ -41,29 +44,81 @@ const link = async args => {
     : linkPkg()
 }
 
+// Returns a list of items that can't be fulfilled by
+// things found in the current arborist inventory
+const missingArgsFromTree = (tree, args) => {
+  const foundNodes = []
+  const missing = args.filter(a => {
+    const arg = npa(a)
+    const nodes = tree.children.values()
+    const argFound = [...nodes].every(node => {
+      // TODO: write tests for unmatching version specs, this is hard to test
+      // atm but should be simple once we have a mocked registry again
+      if (arg.name !== node.name /* istanbul ignore next */ || (
+        arg.version &&
+        !semver.satisfies(node.version, arg.version)
+      )) {
+        foundNodes.push(node)
+        return true
+      }
+    })
+    return argFound
+  })
+
+  // remote nodes from the loaded tree in order
+  // to avoid dropping them later when reifying
+  for (const node of foundNodes) {
+    node.parent = null
+  }
+
+  return missing
+}
+
 const linkInstall = async args => {
   // load current packages from the global space,
   // and then add symlinks installs locally
   const globalTop = resolve(npm.globalDir, '..')
-  const globalArb = new Arborist({
+  const globalOpts = {
     ...npm.flatOptions,
     path: globalTop,
-    global: true
+    global: true,
+    prune: false
+  }
+  const globalArb = new Arborist(globalOpts)
+
+  // get only current top-level packages from the global space
+  const globals = await globalArb.loadActual({
+    filter: (node, kid) =>
+      !node.isRoot || args.some(a => npa(a).name === kid)
   })
 
-  const globals = await globalArb.loadActual()
+  // any extra arg that is missing from the current
+  // global space should be reified there first
+  const missing = missingArgsFromTree(globals, args)
+  await globalArb.reify({
+    ...globalOpts,
+    add: missing
+  })
 
-  const links = [
-    ...globals.children.values()
-  ]
-    .filter(i => args.some(j => j === i.name))
+  // get a list of module names that should be linked in the local prefix
+  const names = []
+  for (const a of args) {
+    const arg = npa(a)
+    names.push(
+      arg.type === 'directory'
+        ? (await rpj(resolve(arg.fetchSpec, 'package.json'))).name
+        : arg.name
+    )
+  }
 
+  // create a new arborist instance for the local prefix and
+  // reify all the pending names as symlinks there
   const localArb = new Arborist({
     ...npm.flatOptions,
     path: npm.prefix
   })
   await localArb.reify({
-    add: links.map(l => `file:${resolve(globalTop, 'node_modules', l.path)}`)
+    add: names.map(l => `file:${resolve(globalTop, 'node_modules', l)}`)
   })
 
   reifyOutput(localArb)

tap-snapshots/test-lib-link.js-TAP.test.js

@@ -6,10 +6,11 @@
  */
 'use strict'
 exports[`test/lib/link.js TAP link global linked pkg to local nm when using args > should create a local symlink to global pkg 1`] = `
-{CWD}/test/lib/link-link-global-linked-pkg-to-local-nm-when-using-args/my-project/node_modules/a -> {CWD}/test/lib/link-link-global-linked-pkg-to-local-nm-when-using-args/global-prefix/lib/node_modules/a
 {CWD}/test/lib/link-link-global-linked-pkg-to-local-nm-when-using-args/my-project/node_modules/@myscope/bar -> {CWD}/test/lib/link-link-global-linked-pkg-to-local-nm-when-using-args/global-prefix/lib/node_modules/@myscope/bar
-{CWD}/test/lib/link-link-global-linked-pkg-to-local-nm-when-using-args/my-project/node_modules/test-pkg-link -> {CWD}/test/lib/link-link-global-linked-pkg-to-local-nm-when-using-args/test-pkg-link
 {CWD}/test/lib/link-link-global-linked-pkg-to-local-nm-when-using-args/my-project/node_modules/@myscope/linked -> {CWD}/test/lib/link-link-global-linked-pkg-to-local-nm-when-using-args/scoped-linked
+{CWD}/test/lib/link-link-global-linked-pkg-to-local-nm-when-using-args/my-project/node_modules/a -> {CWD}/test/lib/link-link-global-linked-pkg-to-local-nm-when-using-args/global-prefix/lib/node_modules/a
+{CWD}/test/lib/link-link-global-linked-pkg-to-local-nm-when-using-args/my-project/node_modules/link-me-too -> {CWD}/test/lib/link-link-global-linked-pkg-to-local-nm-when-using-args/link-me-too
+{CWD}/test/lib/link-link-global-linked-pkg-to-local-nm-when-using-args/my-project/node_modules/test-pkg-link -> {CWD}/test/lib/link-link-global-linked-pkg-to-local-nm-when-using-args/test-pkg-link
 
 `
 

test/lib/link.js

@@ -28,9 +28,11 @@ const printLinks = async (opts) => {
   const arb = new Arborist(opts)
   const tree = await arb.loadActual()
   const linkedItems = [...tree.inventory.values()]
+    .sort((a, b) => a.pkgid.localeCompare(b.pkgid))
   for (const item of linkedItems) {
-    if (item.target)
+    if (item.target) {
       res += `${item.path} -> ${item.target.path}\n`
+    }
   }
   return res
 }
@@ -128,6 +130,12 @@ t.test('link global linked pkg to local nm when using args', (t) => {
         version: '1.0.0'
       })
     },
+    'link-me-too': {
+      'package.json': JSON.stringify({
+        name: 'link-me-too',
+        version: '1.0.0'
+      })
+    },
     'scoped-linked': {
       'package.json': JSON.stringify({
         name: '@myscope/linked',
@@ -155,8 +163,12 @@ t.test('link global linked pkg to local nm when using args', (t) => {
   npm.globalDir = resolve(testdir, 'global-prefix', 'lib', 'node_modules')
   npm.prefix = resolve(testdir, 'my-project')
 
+  const _cwd = process.cwd()
+  process.chdir(npm.prefix)
+
   reifyOutput = async () => {
     reifyOutput = undefined
+    process.chdir(_cwd)
 
     const links = await printLinks({
       path: npm.prefix
@@ -170,7 +182,14 @@ t.test('link global linked pkg to local nm when using args', (t) => {
   // - @myscope/linked: scoped pkg linked to globalDir from local fs
   // - @myscope/bar: prev installed scoped package available in globalDir
   // - a: prev installed package available in globalDir
-  link(['test-pkg-link', '@myscope/linked', '@myscope/bar', 'a'], (err) => {
+  // - file:./link-me-too: pkg that needs to be reified in globalDir first
+  link([
+    'test-pkg-link',
+    '@myscope/linked',
+    '@myscope/bar',
+    'a',
+    'file:../link-me-too'
+  ], (err) => {
     t.ifError(err, 'should not error out')
   })
 })