fix(dev): add actionable error for missing cert file

packages/nuxt-cli/src/dev/cert.ts

@@ -6,6 +6,7 @@ import { existsSync, readFileSync } from 'node:fs'
 import { readFile, writeFile } from 'node:fs/promises'
 import { isIP } from 'node:net'
 import process from 'node:process'
+import { styleText } from 'node:util'
 
 import { join } from 'pathe'
 
@@ -41,18 +42,35 @@ export interface ResolvedCertificate {
 
 export async function resolveCertificate(options: HTTPSOptions): Promise<ResolvedCertificate> {
   if (options.pfx) {
-    return { pfx: await readFile(options.pfx), pfxPath: options.pfx, passphrase: options.passphrase }
+    return { pfx: await readCertificateFile(options.pfx, '--https.pfx'), pfxPath: options.pfx, passphrase: options.passphrase }
   }
   if (options.cert && options.key) {
     const [cert, key] = await Promise.all([
-      readFile(options.cert, 'utf8'),
-      readFile(options.key, 'utf8'),
+      readCertificateFile(options.cert, '--https.cert'),
+      readCertificateFile(options.key, '--https.key'),
     ])
-    return { cert, key, passphrase: options.passphrase }
+    return { cert: cert.toString('utf8'), key: key.toString('utf8'), passphrase: options.passphrase }
   }
   return generateCertificate(options)
 }
 
+/** Read a file the user pointed `--https.*` at, naming the flag when it cannot be read. */
+async function readCertificateFile(path: string, flag: string): Promise<Buffer> {
+  try {
+    return await readFile(path)
+  }
+  catch (error) {
+    const reason = (error as NodeJS.ErrnoException).code === 'ENOENT'
+      ? `There is no file at ${styleText('cyan', path)}`
+      : `Cannot read ${styleText('cyan', path)} (${(error as NodeJS.ErrnoException).code})`
+    throw new ActionableError([
+      `${styleText('red', reason)}${styleText('red', ', given as')} ${styleText('cyan', flag)}${styleText('red', '.')}`,
+      '',
+      `Point ${styleText('cyan', flag)} at a readable file, or drop it and let Nuxt generate a certificate.`,
+    ].join('\n'))
+  }
+}
+
 /** Regenerate rather than serve a certificate that expires within the day. */
 const CERT_MIN_REMAINING_MS = 24 * 60 * 60 * 1000
 

packages/nuxt-cli/test/unit/dev-cert.spec.ts

@@ -0,0 +1,48 @@
+import { mkdtemp, rm, writeFile } from 'node:fs/promises'
+import { tmpdir } from 'node:os'
+import { join } from 'node:path'
+
+import { afterEach, describe, expect, it } from 'vitest'
+
+import { resolveCertificate } from '../../src/dev/cert'
+
+const dirs: string[] = []
+
+afterEach(async () => {
+  await Promise.all(dirs.splice(0).map(dir => rm(dir, { recursive: true, force: true, maxRetries: 3 })))
+})
+
+async function scratch(): Promise<string> {
+  const dir = await mkdtemp(join(tmpdir(), 'nuxi-cert-'))
+  dirs.push(dir)
+  return dir
+}
+
+describe('resolving a certificate the user supplied', () => {
+  it('should read the pair it is pointed at', async () => {
+    const dir = await scratch()
+    await writeFile(join(dir, 'cert.pem'), 'certificate')
+    await writeFile(join(dir, 'key.pem'), 'private key')
+
+    await expect(resolveCertificate({ cert: join(dir, 'cert.pem'), key: join(dir, 'key.pem') }))
+      .resolves
+      .toMatchObject({ cert: 'certificate', key: 'private key' })
+  })
+
+  it('should name the missing file and the flag that pointed at it', async () => {
+    const dir = await scratch()
+    await writeFile(join(dir, 'key.pem'), 'private key')
+
+    await expect(resolveCertificate({ cert: join(dir, 'absent.pem'), key: join(dir, 'key.pem') }))
+      .rejects
+      .toThrow(/There is no file at .*absent\.pem, given as --https\.cert/)
+  })
+
+  it('should say the same for a keystore', async () => {
+    const dir = await scratch()
+
+    await expect(resolveCertificate({ pfx: join(dir, 'absent.p12') }))
+      .rejects
+      .toThrow(/absent\.p12, given as --https\.pfx/)
+  })
+})