feat(exec): replace the npm process with the command instead of waiting for it

lib/commands/exec.js

@@ -29,7 +29,7 @@ class Exec extends BaseCommand {
   static isShellout = true
 
   async exec (args) {
-    return this.callExec(args)
+    return this.callExec(args, { replaceProcess: true })
   }
 
   async execWorkspaces (args) {
@@ -42,7 +42,7 @@ class Exec extends BaseCommand {
     }
   }
 
-  async callExec (args, { locationMsg, runPath } = {}) {
+  async callExec (args, { locationMsg, runPath, replaceProcess = false }) {
     let localBin = this.npm.localBin
     let pkgPath = this.npm.localPrefix
 
@@ -104,6 +104,7 @@ class Exec extends BaseCommand {
       locationMsg,
       // packages that need to be installed
       packages,
+      replaceProcess,
       // path where node_modules is
       path: this.npm.localPrefix,
       // where to look for package.json#bin entries first

test/lib/commands/exec.js

@@ -4,6 +4,14 @@ const path = require('node:path')
 const { load: loadMockNpm } = require('../../fixtures/mock-npm.js')
 const MockRegistry = require('@npmcli/mock-registry')
 
+// npm exec replaces its own process with the command when it can, which would
+// replace this test runner, so force the spawn path here.
+const { execve } = process
+process.execve = undefined
+t.teardown(() => {
+  process.execve = execve
+})
+
 t.test('call with args', async t => {
   const { npm } = await loadMockNpm(t, {
     config: {
@@ -404,3 +412,37 @@ t.test('exec reads .npmrc policy even when project package.json has a different
   await npm.exec('exec', ['some-pkg'])
   t.strictSame(capturedOpts.allowScripts, { canvas: true })
 })
+
+t.test('replaces the npm process for a single command', async t => {
+  let capturedOpts
+  const { npm } = await loadMockNpm(t, {
+    mocks: {
+      libnpmexec: async (opts) => {
+        capturedOpts = opts
+      },
+    },
+  })
+  await npm.exec('exec', ['some-pkg'])
+  t.equal(capturedOpts.replaceProcess, true)
+})
+
+t.test('keeps the npm process when running in workspaces', async t => {
+  const captured = []
+  const { npm } = await loadMockNpm(t, {
+    prefixDir: {
+      'package.json': JSON.stringify({ name: 'root', workspaces: ['packages/*'] }),
+      packages: {
+        a: { 'package.json': JSON.stringify({ name: 'a', version: '1.0.0' }) },
+        b: { 'package.json': JSON.stringify({ name: 'b', version: '1.0.0' }) },
+      },
+    },
+    config: { workspaces: true },
+    mocks: {
+      libnpmexec: async (opts) => {
+        captured.push(opts.replaceProcess)
+      },
+    },
+  })
+  await npm.exec('exec', ['some-pkg'])
+  t.strictSame(captured, [false, false])
+})

workspaces/libnpmexec/lib/run-script.js

@@ -27,6 +27,7 @@ const run = async ({
 
   // turn list of args into command string
   const script = call || args.shift() || scriptShell
+  const replaceProcess = !!flatOptions.replaceProcess && script !== scriptShell
 
   // do the fakey runScript dance
   // still should work if no package.json in cwd
@@ -38,7 +39,7 @@ const run = async ({
     ...realPkg,
     scripts: {
       ...(realPkg.scripts || {}),
-      npx: script,
+      npx: replaceProcess && !call && scriptShell === 'sh' ? `exec ${script}` : script,
     },
   }
 
@@ -69,6 +70,7 @@ const run = async ({
     args,
     stdio: 'inherit',
     scriptShell,
+    replaceProcess,
   })
 }
 

workspaces/libnpmexec/test/run-script.js

@@ -157,3 +157,57 @@ t.test('isNotWindows', async t => {
   // need both arguments and no arguments for code coverage
   await runScript()
 })
+
+t.test('replaceProcess', async t => {
+  const runWith = async (t, opts) => {
+    let received
+    const runScript = t.mock('../lib/run-script.js', {
+      'ci-info': { isCI: true },
+      '@npmcli/run-script': async (o) => {
+        received = o
+      },
+      '../lib/is-windows.js': false,
+    })
+    await runScript({
+      args: [],
+      call: '',
+      path: '',
+      runPath: '',
+      scriptShell: 'sh',
+      ...opts,
+      flatOptions: { replaceProcess: true, ...opts.flatOptions },
+    })
+    return received
+  }
+
+  t.test('execs the bin through the shell', async t => {
+    const o = await runWith(t, { args: ['foo', 'bar'] })
+    t.equal(o.replaceProcess, true)
+    t.equal(o.pkg.scripts.npx, `exec 'foo'`)
+    t.strictSame(o.args, ['bar'])
+  })
+
+  t.test('keeps --call scripts as they are', async t => {
+    const o = await runWith(t, { call: 'foo && bar' })
+    t.equal(o.replaceProcess, true)
+    t.equal(o.pkg.scripts.npx, 'foo && bar')
+  })
+
+  t.test('does not prefix exec for a custom script-shell', async t => {
+    const o = await runWith(t, { args: ['foo'], scriptShell: 'bash' })
+    t.equal(o.replaceProcess, true)
+    t.equal(o.pkg.scripts.npx, `'foo'`)
+  })
+
+  t.test('never replaces the process in interactive mode', async t => {
+    const o = await runWith(t, {})
+    t.equal(o.replaceProcess, false)
+    t.equal(o.pkg.scripts.npx, 'sh')
+  })
+
+  t.test('is off unless requested', async t => {
+    const o = await runWith(t, { args: ['foo'], flatOptions: { replaceProcess: false } })
+    t.equal(o.replaceProcess, false)
+    t.equal(o.pkg.scripts.npx, `'foo'`)
+  })
+})