fix(core): improve no-TTY modules purge hint (#10973)

* fix(core): clarify non-interactive modules purge guidance

Add confirmModulesPurge=false workaround to the no-TTY error hint and
add a regression test for the non-interactive purge confirmation flow.

Refs #6778

* test(core): assert non-tty purge hint on error hint field

---------

Co-authored-by: zubeyralmaho <zubeyralmaho@users.noreply.github.com>

.changeset/fix-non-interactive-modules-purge-hint.md

@@ -0,0 +1,10 @@
+---
+"@pnpm/core": patch
+"pnpm": patch
+---
+
+Improve the non-interactive modules purge error hint to include the `confirmModulesPurge=false` workaround.
+
+When pnpm needs to recreate `node_modules` but no TTY is available, the error now suggests either setting `CI=true` or disabling the purge confirmation prompt via `confirmModulesPurge=false`.
+
+Adds a regression test for the non-TTY flow.

pkg-manager/core/src/install/validateModules.ts

@@ -151,7 +151,7 @@ async function purgeModulesDirsOfImporters (
   if (opts.confirmModulesPurge ?? true) {
     if (!process.stdin.isTTY) {
       throw new PnpmError('ABORTED_REMOVE_MODULES_DIR_NO_TTY', 'Aborted removal of modules directory due to no TTY', {
-        hint: 'If you are running pnpm in CI, set the CI environment variable to "true".',
+        hint: 'If you are running pnpm in CI, set the CI environment variable to "true", or set "confirmModulesPurge" to "false".',
       })
     }
     const confirmed = await enquirer.prompt<{ question: boolean }>({

pkg-manager/core/test/breakingChanges.ts

@@ -1,5 +1,6 @@
 import fs from 'node:fs'
 import path from 'node:path'
+import util from 'node:util'
 
 import { WANTED_LOCKFILE } from '@pnpm/constants'
 import { addDependenciesToPackage, install } from '@pnpm/core'
@@ -102,6 +103,32 @@ test('do not fail on non-compatible store when forced during named installation'
   })
 })
 
+test('fail fast with actionable hint on non-TTY when modules purge needs confirmation', async () => {
+  prepareEmpty()
+  const opts = testDefaults()
+
+  await saveModulesYaml('0.50.0', opts.storeDir)
+
+  const originalIsTTY = process.stdin.isTTY
+  Object.defineProperty(process.stdin, 'isTTY', { value: false, configurable: true })
+
+  let err: unknown
+  try {
+    await install({}, opts)
+  } catch (_err: unknown) {
+    err = _err
+  } finally {
+    Object.defineProperty(process.stdin, 'isTTY', { value: originalIsTTY, configurable: true })
+  }
+
+  expect(util.types.isNativeError(err)).toBeTruthy()
+  if (util.types.isNativeError(err)) {
+    expect('code' in err && err.code).toBe('ERR_PNPM_ABORTED_REMOVE_MODULES_DIR_NO_TTY')
+    expect(err.message).toContain('no TTY')
+    expect('hint' in err && typeof err.hint === 'string' && err.hint).toContain('confirmModulesPurge')
+  }
+})
+
 async function saveModulesYaml (pnpmVersion: string, storeDir: string) {
   fs.mkdirSync('node_modules')
   fs.writeFileSync('node_modules/.modules.yaml', `packageManager: pnpm@${pnpmVersion}\nstoreDir: ${storeDir}`)