restore old npx behavior of running existing bins first

lib/exec.js

@@ -59,6 +59,8 @@ const crypto = require('crypto')
 const pacote = require('pacote')
 const npa = require('npm-package-arg')
 const escapeArg = require('./utils/escape-arg.js')
+const fileExists = require('./utils/file-exists.js')
+const PATH = require('./utils/path.js')
 
 const cmd = (args, cb) => exec(args).then(() => cb()).catch(cb)
 
@@ -69,8 +71,38 @@ const exec = async args => {
     throw usage
   }
 
+  const pathArr = [...PATH]
+
   const needPackageCommandSwap = args.length && !packages.length
+  // if there's an argument and no package has been explicitly asked for
+  // check the local and global bin paths for a binary named the same as
+  // the argument and run it if it exists, otherwise fall through to
+  // the behavior of treating the single argument as a package name
   if (needPackageCommandSwap) {
+    let binExists = false
+    if (await fileExists(`${npm.localBin}/${args[0]}`)) {
+      pathArr.unshift(npm.localBin)
+      binExists = true
+    } else if (await fileExists(`${npm.globalBin}/${args[0]}`)) {
+      pathArr.unshift(npm.globalBin)
+      binExists = true
+    }
+
+    if (binExists) {
+      return await runScript({
+        cmd: args.map(escapeArg).join(' ').trim(),
+        banner: false,
+        // we always run in cwd, not --prefix
+        path: process.cwd(),
+        stdioString: true,
+        event: 'npx',
+        env: {
+          PATH: pathArr.join(delimiter)
+        },
+        stdio: 'inherit'
+      })
+    }
+
     packages.push(args[0])
   }
 
@@ -111,7 +143,6 @@ const exec = async args => {
   // do we have all the packages in manifest list?
   const needInstall = manis.some(mani => manifestMissing(tree, mani))
 
-  const pathArr = [process.env.PATH]
   if (needInstall) {
     const installDir = cacheInstallDir(packages)
     await mkdirp(installDir)

test/lib/exec.js

@@ -19,6 +19,7 @@ class Arborist {
 }
 
 let PROGRESS_ENABLED = true
+let PROGRESS_IGNORED = false
 const npm = {
   flatOptions: {
     yes: true,
@@ -27,6 +28,8 @@ const npm = {
     legacyPeerDeps: false
   },
   localPrefix: 'local-prefix',
+  localBin: 'local-bin',
+  globalBin: 'global-bin',
   config: {
     get: k => {
       if (k !== 'cache') {
@@ -48,7 +51,7 @@ const npm = {
 const RUN_SCRIPTS = []
 const runScript = async opt => {
   RUN_SCRIPTS.push(opt)
-  if (PROGRESS_ENABLED) {
+  if (!PROGRESS_IGNORED && PROGRESS_ENABLED) {
     throw new Error('progress not disabled during run script!')
   }
 }
@@ -71,6 +74,8 @@ const read = (options, cb) => {
   process.nextTick(() => cb(READ_ERROR, READ_RESULT))
 }
 
+const PATH = require('../../lib/utils/path.js')
+
 const exec = requireInject('../../lib/exec.js', {
   '@npmcli/arborist': Arborist,
   '@npmcli/run-script': runScript,
@@ -88,12 +93,63 @@ t.afterEach(cb => {
   READ.length = 0
   READ_RESULT = ''
   READ_ERROR = null
+  PROGRESS_IGNORED = false
   npm.flatOptions.legacyPeerDeps = false
   npm.flatOptions.package = []
   npm.flatOptions.call = ''
+  npm.localBin = 'local-bin'
+  npm.globalBin = 'global-bin'
   cb()
 })
 
+t.test('npx foo, bin already exists locally', async t => {
+  const path = t.testdir({
+    foo: 'just some file'
+  })
+
+  PROGRESS_IGNORED = true
+  npm.localBin = path
+
+  await exec(['foo'], er => {
+    t.ifError(er, 'npm exec')
+  })
+  t.strictSame(RUN_SCRIPTS, [{
+    cmd: 'foo',
+    banner: false,
+    path: process.cwd(),
+    stdioString: true,
+    event: 'npx',
+    env: {
+      PATH: [path, ...PATH].join(delimiter)
+    },
+    stdio: 'inherit'
+  }])
+})
+
+t.test('npx foo, bin already exists globally', async t => {
+  const path = t.testdir({
+    foo: 'just some file'
+  })
+
+  PROGRESS_IGNORED = true
+  npm.globalBin = path
+
+  await exec(['foo'], er => {
+    t.ifError(er, 'npm exec')
+  })
+  t.strictSame(RUN_SCRIPTS, [{
+    cmd: 'foo',
+    banner: false,
+    path: process.cwd(),
+    stdioString: true,
+    event: 'npx',
+    env: {
+      PATH: [path, ...PATH].join(delimiter)
+    },
+    stdio: 'inherit'
+  }])
+})
+
 t.test('npm exec foo, already present locally', async t => {
   const path = t.testdir()
   npm.localPrefix = path