feat: add replaceProcess option to exec the script in place of npm

lib/run-script-pkg.js

@@ -67,6 +67,11 @@ const runScriptPkg = async options => {
     stdioString,
   })
 
+  if (options.replaceProcess && stdio === 'inherit' && promiseSpawn.canExecve()) {
+    inputEnd()
+    return promiseSpawn.execve(spawnShell, spawnArgs, spawnOpts)
+  }
+
   const p = promiseSpawn(spawnShell, spawnArgs, spawnOpts, {
     event,
     script: cmd,

test/replace-process.js

@@ -0,0 +1,70 @@
+const t = require('tap')
+const spawk = require('spawk')
+const realPromiseSpawn = require('@npmcli/promise-spawn')
+
+const emptyDir = t.testdir({})
+
+const mockRunScript = (t, { canExecve }) => {
+  const calls = []
+  const promiseSpawn = Object.assign((...args) => realPromiseSpawn(...args), {
+    canExecve: () => canExecve,
+    execve: async (...args) => {
+      calls.push(args)
+    },
+  })
+  const runScript = t.mock('../lib/run-script.js', {
+    '../lib/run-script-pkg.js': t.mock('../lib/run-script-pkg.js', {
+      '@npmcli/promise-spawn': promiseSpawn,
+    }),
+  })
+  return { runScript, calls }
+}
+
+const options = (overrides) => ({
+  event: 'npx',
+  path: emptyDir,
+  scriptShell: 'sh',
+  stdio: 'inherit',
+  cmd: 'bar',
+  args: ['baz qux'],
+  replaceProcess: true,
+  pkg: { scripts: {} },
+  ...overrides,
+})
+
+t.test('replaces the process when asked to and possible', async t => {
+  const { runScript, calls } = mockRunScript(t, { canExecve: true })
+  await runScript(options())
+  t.equal(calls.length, 1)
+  const [cmd, args, opts] = calls[0]
+  t.equal(cmd, 'bar')
+  t.strictSame(args, ['baz qux'])
+  t.equal(opts.shell, 'sh')
+  t.equal(opts.cwd, emptyDir)
+  t.equal(opts.env.npm_lifecycle_event, 'npx')
+  t.equal(opts.env.npm_lifecycle_script, 'bar')
+})
+
+t.test('spawns when execve is not available', async t => {
+  const { runScript, calls } = mockRunScript(t, { canExecve: false })
+  spawk.spawn('sh', a => a.includes("bar 'baz qux'"))
+  await runScript(options())
+  t.strictSame(calls, [])
+  t.ok(spawk.done())
+})
+
+t.test('spawns when stdio is not inherited', async t => {
+  const { runScript, calls } = mockRunScript(t, { canExecve: true })
+  spawk.spawn('sh', a => a.includes("bar 'baz qux'"))
+  await runScript(options({ stdio: 'pipe' }))
+  t.strictSame(calls, [])
+  t.ok(spawk.done())
+})
+
+t.test('spawns when not asked to replace the process', async t => {
+  const { runScript, calls } = mockRunScript(t, { canExecve: true })
+  spawk.spawn('sh', a => a.includes("bar 'baz qux'"))
+  await runScript(options({ replaceProcess: false }))
+  t.strictSame(calls, [])
+  t.ok(spawk.done())
+})