Skip auto-install for missing deps in CI

packages/next/lib/typescript/missingDependencyError.ts

@@ -0,0 +1,43 @@
+import chalk from 'next/dist/compiled/chalk'
+
+import { getOxfordCommaList } from '../oxford-comma-list'
+import { MissingDependency } from '../has-necessary-dependencies'
+import { FatalError } from '../fatal-error'
+import { getPkgManager } from '../helpers/get-pkg-manager'
+
+export async function missingDepsError(
+  dir: string,
+  missingPackages: MissingDependency[]
+) {
+  const packagesHuman = getOxfordCommaList(missingPackages.map((p) => p.pkg))
+  const packagesCli = missingPackages.map((p) => p.pkg).join(' ')
+  const packageManager = getPkgManager(dir)
+
+  const removalMsg =
+    '\n\n' +
+    chalk.bold(
+      'If you are not trying to use TypeScript, please remove the ' +
+        chalk.cyan('tsconfig.json') +
+        ' file from your package root (and any TypeScript files in your pages directory).'
+    )
+
+  throw new FatalError(
+    chalk.bold.red(
+      `It looks like you're trying to use TypeScript but do not have the required package(s) installed.`
+    ) +
+      '\n\n' +
+      chalk.bold(`Please install ${chalk.bold(packagesHuman)} by running:`) +
+      '\n\n' +
+      `\t${chalk.bold.cyan(
+        (packageManager === 'yarn'
+          ? 'yarn add --dev'
+          : packageManager === 'pnpm'
+          ? 'pnpm install --save-dev'
+          : 'npm install --save-dev') +
+          ' ' +
+          packagesCli
+      )}` +
+      removalMsg +
+      '\n'
+  )
+}

packages/next/lib/verifyTypeScriptSetup.ts

@@ -14,6 +14,8 @@ import { TypeCheckResult } from './typescript/runTypeCheck'
 import { writeAppTypeDeclarations } from './typescript/writeAppTypeDeclarations'
 import { writeConfigurationDefaults } from './typescript/writeConfigurationDefaults'
 import { installDependencies } from './install-dependencies'
+import { isCI } from '../telemetry/ci-info'
+import { missingDepsError } from './typescript/missingDependencyError'
 
 const requiredPackages = [
   {
@@ -64,6 +66,11 @@ export async function verifyTypeScriptSetup({
     )
 
     if (deps.missing?.length > 0) {
+      if (isCI) {
+        // we don't attempt auto install in CI to avoid side-effects
+        // and instead log the error for installing needed packages
+        await missingDepsError(dir, deps.missing)
+      }
       console.log(
         chalk.bold.yellow(
           `It looks like you're trying to use TypeScript but do not have the required package(s) installed.`
@@ -82,7 +89,8 @@ export async function verifyTypeScriptSetup({
         if (err && typeof err === 'object' && 'command' in err) {
           console.error(
             `Failed to install required TypeScript dependencies, please install them manually to continue:\n` +
-              (err as any).command
+              (err as any).command +
+              '\n'
           )
         }
         throw err

test/development/typescript-auto-install/index.test.ts

@@ -17,6 +17,16 @@ describe('typescript-auto-install', () => {
           } 
         `,
       },
+      env: {
+        // unset CI env as this skips the auto-install behavior
+        // being tested
+        CI: '',
+        CIRCLECI: '',
+        GITHUB_ACTIONS: '',
+        CONTINUOUS_INTEGRATION: '',
+        RUN_ID: '',
+        BUILD_NUMBER: '',
+      },
       startCommand: 'yarn next dev',
       installCommand: 'yarn',
       dependencies: {},

test/production/ci-missing-typescript-deps/index.test.ts

@@ -0,0 +1,33 @@
+import { createNext } from 'e2e-utils'
+
+describe('ci-missing-typescript-deps', () => {
+  it('should show missing TypeScript dependencies error in CI', async () => {
+    const next = await createNext({
+      files: {
+        'pages/index.tsx': `
+          export default function Page() {
+            return <p>hello world</p>
+          }
+        `,
+      },
+      env: {
+        CI: '1',
+      },
+      skipStart: true,
+    })
+    try {
+      let error
+      await next.start().catch((err) => {
+        error = err
+      })
+
+      expect(error).toBeDefined()
+      expect(next.cliOutput).toContain(
+        `It looks like you're trying to use TypeScript but do not have the required package(s) installed.`
+      )
+      expect(next.cliOutput).toContain(`Please install`)
+    } finally {
+      await next.destroy()
+    }
+  })
+})