Validate Astro frontmatter JS/TS on compiler error

.changeset/dirty-guests-wash.md

@@ -0,0 +1,5 @@
+---
+'astro': patch
+---
+
+Improve error message on bad JS/TS frontmatter

packages/astro/src/vite-plugin-astro/index.ts

@@ -10,6 +10,7 @@ import { transform } from '@astrojs/compiler';
 import { AstroDevServer } from '../core/dev/index.js';
 import { getViteTransform, TransformHook, transformWithVite } from './styles.js';
 
+const FRONTMATTER_PARSE_REGEXP = /^\-\-\-(.*)^\-\-\-/ms;
 interface AstroPluginOptions {
  config: AstroConfig;
  devServer?: AstroDevServer;
@@ -87,14 +88,37 @@ export default function astro({ config, devServer }: AstroPluginOptions): vite.P
  // throw CSS transform errors here if encountered
  if (cssTransformError) throw cssTransformError;
 
- // Compile `.ts` to `.js`
+ // Compile all TypeScript to JavaScript.
+ // Also, catches invalid JS/TS in the compiled output before returning.
  const { code, map } = await esbuild.transform(tsResult.code, { loader: 'ts', sourcemap: 'external', sourcefile: id });
 
  return {
  code,
  map,
  };
  } catch (err: any) {
+ // Verify frontmatter: a common reason that this plugin fails is that
+ // the user provided invalid JS/TS in the component frontmatter.
+ // If the frontmatter is invalid, the `err` object may be a compiler
+ // panic or some other vague/confusing compiled error message.
+ //
+ // Before throwing, it is better to verify the frontmatter here, and
+ // let esbuild throw a more specific exception if the code is invalid.
+ // If frontmatter is valid or cannot be parsed, then continue.
+ const scannedFrontmatter = FRONTMATTER_PARSE_REGEXP.exec(source);
+ if (scannedFrontmatter) {
+ try {
+ await esbuild.transform(scannedFrontmatter[1], { loader: 'ts', sourcemap: false, sourcefile: id });
+ } catch (frontmatterErr: any) {
+ // Improve the error by replacing the phrase "unexpected end of file"
+ // with "unexpected end of frontmatter" in the esbuild error message.
+ if (frontmatterErr && frontmatterErr.message) {
+ frontmatterErr.message = frontmatterErr.message.replace('end of file', 'end of frontmatter');
+ }
+ throw frontmatterErr;
+ }
+ }
+
  // improve compiler errors
  if (err.stack.includes('wasm-function')) {
  const search = new URLSearchParams({

packages/astro/test/errors.test.js

@@ -1,10 +1,6 @@
 import { expect } from 'chai';
-import os from 'os';
 import { loadFixture } from './test-utils.js';
 
-// TODO: fix these tests on macOS
-const isMacOS = os.platform() === 'darwin';
-
 let fixture;
 let devServer;
 
@@ -21,231 +17,136 @@ before(async () => {
 
 describe('Error display', () => {
  describe('Astro', () => {
- // This test is redundant w/ runtime error since it no longer produces an Astro syntax error
- it.skip('syntax error', async () => {
- if (isMacOS) return;
-
+ it('syntax error in template', async () => {
  const res = await fixture.fetch('/astro-syntax-error');
-
- // 500 returned
  expect(res.status).to.equal(500);
+ const body = await res.text();
+ console.log(res.body);
+ expect(body).to.include('Unexpected "}"');
+ });
 
- // error message includes "unrecoverable error"
+ it('syntax error in frontmatter', async () => {
+ const res = await fixture.fetch('/astro-frontmatter-syntax-error');
+ expect(res.status).to.equal(500);
  const body = await res.text();
  console.log(res.body);
- expect(body).to.include('unrecoverable error');
+ expect(body).to.include('Unexpected end of frontmatter');
  });
 
  it('runtime error', async () => {
- if (isMacOS) return;
-
  const res = await fixture.fetch('/astro-runtime-error');
-
- // 500 returned
  expect(res.status).to.equal(500);
-
- // error message contains error
  const body = await res.text();
  expect(body).to.include('ReferenceError: title is not defined');
-
- // TODO: improve stacktrace
+ // TODO: improve and test stacktrace
  });
 
  it('hydration error', async () => {
- if (isMacOS) return;
-
  const res = await fixture.fetch('/astro-hydration-error');
-
- // 500 returned
  expect(res.status).to.equal(500);
-
- // error message contains error
  const body = await res.text();
-
- // error message contains error
  expect(body).to.include('Error: invalid hydration directive');
  });
 
  it('client:media error', async () => {
- if (isMacOS) return;
-
  const res = await fixture.fetch('/astro-client-media-error');
-
- // 500 returned
  expect(res.status).to.equal(500);
-
- // error message contains error
  const body = await res.text();
-
- // error message contains error
  expect(body).to.include('Error: Media query must be provided');
  });
  });
 
  describe('JS', () => {
  it('syntax error', async () => {
- if (isMacOS) return;
-
  const res = await fixture.fetch('/js-syntax-error');
-
- // 500 returnd
  expect(res.status).to.equal(500);
-
- // error message is helpful
  const body = await res.text();
  expect(body).to.include('Parse failure');
  });
 
  it('runtime error', async () => {
- if (isMacOS) return;
-
  const res = await fixture.fetch('/js-runtime-error');
-
- // 500 returnd
  expect(res.status).to.equal(500);
-
- // error message is helpful
  const body = await res.text();
  expect(body).to.include('ReferenceError: undefinedvar is not defined');
  });
  });
 
  describe('Preact', () => {
  it('syntax error', async () => {
- if (isMacOS) return;
-
  const res = await fixture.fetch('/preact-syntax-error');
-
- // 500 returned
  expect(res.status).to.equal(500);
-
- // error message is helpful
  const body = await res.text();
  expect(body).to.include('Syntax error');
  });
 
  it('runtime error', async () => {
- if (isMacOS) return;
-
  const res = await fixture.fetch('/preact-runtime-error');
-
- // 500 returned
  expect(res.status).to.equal(500);
-
- // error message is helpful
  const body = await res.text();
  expect(body).to.include('Error: PreactRuntimeError');
  });
  });
 
  describe('React', () => {
  it('syntax error', async () => {
- if (isMacOS) return;
-
  const res = await fixture.fetch('/react-syntax-error');
-
- // 500 returned
  expect(res.status).to.equal(500);
-
- // error message is helpful
  const body = await res.text();
  expect(body).to.include('Syntax error');
  });
 
  it('runtime error', async () => {
- if (isMacOS) return;
-
  const res = await fixture.fetch('/react-runtime-error');
-
- // 500 returned
  expect(res.status).to.equal(500);
-
- // error message is helpful
  const body = await res.text();
  expect(body).to.include('Error: ReactRuntimeError');
  });
  });
 
  describe('Solid', () => {
  it('syntax error', async () => {
- if (isMacOS) return;
-
  const res = await fixture.fetch('/solid-syntax-error');
-
- // 500 returned
  expect(res.status).to.equal(500);
-
- // error message is helpful
  const body = await res.text();
  expect(body).to.include('Syntax error');
  });
 
  it('runtime error', async () => {
- if (isMacOS) return;
-
  const res = await fixture.fetch('/solid-runtime-error');
-
- // 500 returned
  expect(res.status).to.equal(500);
-
- // error message is helpful
  const body = await res.text();
  expect(body).to.include('Error: SolidRuntimeError');
  });
  });
 
  describe('Svelte', () => {
  it('syntax error', async () => {
- if (isMacOS) return;
-
  const res = await fixture.fetch('/svelte-syntax-error');
-
- // 500 returned
  expect(res.status).to.equal(500);
-
- // error message is helpful
  const body = await res.text();
  expect(body).to.include('ParseError');
  });
 
  it('runtime error', async () => {
- if (isMacOS) return;
-
  const res = await fixture.fetch('/svelte-runtime-error');
-
- // 500 returned
  expect(res.status).to.equal(500);
-
- // error message is helpful
  const body = await res.text();
  expect(body).to.include('Error: SvelteRuntimeError');
  });
  });
 
  describe('Vue', () => {
  it('syntax error', async () => {
- if (isMacOS) return;
-
  const res = await fixture.fetch('/vue-syntax-error');
-
  const body = await res.text();
-
- // 500 returned
  expect(res.status).to.equal(500);
-
- // error message is helpful
  expect(body).to.include('Parse failure');
  });
 
  it('runtime error', async () => {
- if (isMacOS) return;
-
  const res = await fixture.fetch('/vue-runtime-error');
-
- // 500 returned
  expect(res.status).to.equal(500);
-
- // error message is helpful
  const body = await res.text();
  expect(body).to.match(/Cannot read.*undefined/); // note: error differs slightly between Node versions
  });

packages/astro/test/fixtures/errors/src/pages/astro-frontmatter-syntax-error.astro

@@ -0,0 +1,4 @@
+---
+{
+---
+<h1>Testing bad JS in frontmatter</h1>