feat(mdx-loader): Remark plugin to report unused MDX / Markdown directives

argos/playwright.config.ts

@@ -14,6 +14,8 @@ import type {PlaywrightTestConfig} from '@playwright/test';
 const config: PlaywrightTestConfig = {
   testDir: './tests',
 
+  timeout: 60000,
+
   reporter: [['list'], ['@argos-ci/playwright/reporter']],
 
   // Run website production built

argos/tests/screenshot.spec.ts

@@ -36,8 +36,12 @@ function isBlacklisted(pathname: string) {
   }
   // Some paths explicitly blacklisted
   const BlacklistedPathnames: string[] = [
-    '/feature-requests', // Flaky because of Canny widget
-    '/community/canary', // Flaky because of dynamic canary version fetched from npm
+    // Flaky because of Canny widget
+    '/feature-requests',
+    // Flaky because of dynamic canary version fetched from npm
+    '/community/canary',
+    // Long blog post with many image carousels, often timeouts
+    '/blog/2022/08/01/announcing-docusaurus-2.0',
   ];
 
   return (

packages/docusaurus-mdx-loader/src/loader.ts

@@ -11,6 +11,7 @@ import {
   parseFrontMatter,
   escapePath,
   getFileLoaderUtils,
+  getWebpackLoaderCompilerName,
 } from '@docusaurus/utils';
 import stringifyObject from 'stringify-object';
 import preprocessor from './preprocessor';
@@ -134,10 +135,12 @@ export async function mdxLoader(
   this: LoaderContext<Options>,
   fileString: string,
 ): Promise<void> {
+  const compilerName = getWebpackLoaderCompilerName(this);
   const callback = this.async();
   const filePath = this.resourcePath;
   const reqOptions: Options = this.getOptions();
   const {query} = this;
+
   ensureMarkdownConfig(reqOptions);
 
   const {frontMatter} = parseFrontMatter(fileString);
@@ -165,6 +168,7 @@ export async function mdxLoader(
       content: preprocessedContent,
       filePath,
       frontMatter,
+      compilerName,
     });
   } catch (errorUnknown) {
     const error = errorUnknown as Error;

packages/docusaurus-mdx-loader/src/processor.ts

@@ -15,8 +15,10 @@ import details from './remark/details';
 import head from './remark/head';
 import mermaid from './remark/mermaid';
 import transformAdmonitions from './remark/admonitions';
+import unusedDirectivesWarning from './remark/unusedDirectives';
 import codeCompatPlugin from './remark/mdx1Compat/codeCompatPlugin';
 import {getFormat} from './format';
+import type {WebpackCompilerName} from '@docusaurus/utils';
 import type {MDXFrontMatter} from './frontMatter';
 import type {Options} from './loader';
 import type {AdmonitionOptions} from './remark/admonitions';
@@ -37,10 +39,12 @@ type SimpleProcessor = {
     content,
     filePath,
     frontMatter,
+    compilerName,
   }: {
     content: string;
     filePath: string;
     frontMatter: {[key: string]: unknown};
+    compilerName: WebpackCompilerName;
   }) => Promise<SimpleProcessorResult>;
 };
 
@@ -123,6 +127,7 @@ async function createProcessorFactory() {
       gfm,
       options.markdownConfig.mdx1Compat.comments ? comment : null,
       ...(options.remarkPlugins ?? []),
+      unusedDirectivesWarning,
     ].filter((plugin): plugin is MDXPlugin => Boolean(plugin));
 
     // codeCompatPlugin needs to be applied last after user-provided plugins
@@ -167,12 +172,13 @@ async function createProcessorFactory() {
     });
 
     return {
-      process: async ({content, filePath, frontMatter}) => {
+      process: async ({content, filePath, frontMatter, compilerName}) => {
         const vfile = new VFile({
           value: content,
           path: filePath,
           data: {
             frontMatter,
+            compilerName,
           },
         });
         return mdxProcessor.process(vfile).then((result) => ({

packages/docusaurus-mdx-loader/src/remark/contentTitle/index.ts

@@ -35,6 +35,7 @@ const plugin: Plugin = function plugin(
     const {toString} = await import('mdast-util-to-string');
     visit(root, 'heading', (headingNode: Heading, index, parent) => {
       if (headingNode.depth === 1) {
+        vfile.data.compilerName;
         vfile.data.contentTitle = toString(headingNode);
         if (removeContentTitle) {
           parent!.children.splice(index, 1);

packages/docusaurus-mdx-loader/src/remark/mermaid/index.ts

@@ -6,6 +6,8 @@
  */
 
 import visit from 'unist-util-visit';
+import {transformNode} from '../utils';
+
 // @ts-expect-error: TODO see https://github.com/microsoft/TypeScript/issues/49721
 import type {Transformer} from 'unified';
 import type {Code} from 'mdast';
@@ -16,10 +18,10 @@ import type {Code} from 'mdast';
 // by theme-mermaid itself
 export default function plugin(): Transformer {
   return (root) => {
-    visit(root, 'code', (node: Code, index, parent) => {
+    visit(root, 'code', (node: Code) => {
       if (node.lang === 'mermaid') {
         // TODO migrate to mdxJsxFlowElement? cf admonitions
-        parent!.children.splice(index, 1, {
+        transformNode(node, {
           type: 'mermaidCodeBlock',
           data: {
             hName: 'mermaid',

packages/docusaurus-mdx-loader/src/remark/transformImage/index.ts

@@ -20,7 +20,7 @@ import visit from 'unist-util-visit';
 import escapeHtml from 'escape-html';
 import sizeOf from 'image-size';
 import logger from '@docusaurus/logger';
-import {assetRequireAttributeValue} from '../utils';
+import {assetRequireAttributeValue, transformNode} from '../utils';
 // @ts-expect-error: TODO see https://github.com/microsoft/TypeScript/issues/49721
 import type {Transformer} from 'unified';
 // @ts-expect-error: TODO see https://github.com/microsoft/TypeScript/issues/49721
@@ -110,14 +110,12 @@ ${(err as Error).message}`;
     }
   }
 
-  Object.keys(jsxNode).forEach(
-    (key) => delete jsxNode[key as keyof typeof jsxNode],
-  );
-
-  jsxNode.type = 'mdxJsxTextElement';
-  jsxNode.name = 'img';
-  jsxNode.attributes = attributes;
-  jsxNode.children = [];
+  transformNode(jsxNode, {
+    type: 'mdxJsxTextElement',
+    name: 'img',
+    attributes,
+    children: [],
+  });
 }
 
 async function ensureImageFileExist(imagePath: string, sourceFilePath: string) {

packages/docusaurus-mdx-loader/src/remark/transformLinks/index.ts

@@ -17,7 +17,7 @@ import {
 } from '@docusaurus/utils';
 import visit from 'unist-util-visit';
 import escapeHtml from 'escape-html';
-import {assetRequireAttributeValue} from '../utils';
+import {assetRequireAttributeValue, transformNode} from '../utils';
 // @ts-expect-error: TODO see https://github.com/microsoft/TypeScript/issues/49721
 import type {Transformer} from 'unified';
 // @ts-expect-error: TODO see https://github.com/microsoft/TypeScript/issues/49721
@@ -90,14 +90,12 @@ async function toAssetRequireNode(
 
   const {children} = node;
 
-  Object.keys(jsxNode).forEach(
-    (key) => delete jsxNode[key as keyof typeof jsxNode],
-  );
-
-  jsxNode.type = 'mdxJsxTextElement';
-  jsxNode.name = 'a';
-  jsxNode.attributes = attributes;
-  jsxNode.children = children;
+  transformNode(jsxNode, {
+    type: 'mdxJsxTextElement',
+    name: 'a',
+    attributes,
+    children,
+  });
 }
 
 async function ensureAssetFileExist(assetPath: string, sourceFilePath: string) {

packages/docusaurus-mdx-loader/src/remark/unusedDirectives/__tests__/__snapshots__/index.test.ts.snap

@@ -0,0 +1,86 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`directives remark plugin - client compiler default behavior for container directives: console 1`] = `
+[
+  [
+    "[WARNING] Docusaurus found 1 unused Markdown directives in file "packages/docusaurus-mdx-loader/src/remark/unusedDirectives/__tests__/__fixtures__/containerDirectives.md"
+- :::unusedDirective (7:1)
+Your content might render in an unexpected way. Visit https://github.com/facebook/docusaurus/pull/9394 to find out why and how to fix it.",
+  ],
+]
+`;
+
+exports[`directives remark plugin - client compiler default behavior for container directives: result 1`] = `
+"<admonition type="danger"><p>Take care of snowstorms...</p></admonition>
+<div><p>unused directive content</p></div>
+<p>:::NotAContainerDirective with a phrase after</p>
+<p>:::</p>
+<p>Phrase before :::NotAContainerDirective</p>
+<p>:::</p>"
+`;
+
+exports[`directives remark plugin - client compiler default behavior for leaf directives: console 1`] = `
+[
+  [
+    "[WARNING] Docusaurus found 1 unused Markdown directives in file "packages/docusaurus-mdx-loader/src/remark/unusedDirectives/__tests__/__fixtures__/leafDirectives.md"
+- ::unusedLeafDirective (1:1)
+Your content might render in an unexpected way. Visit https://github.com/facebook/docusaurus/pull/9394 to find out why and how to fix it.",
+  ],
+]
+`;
+
+exports[`directives remark plugin - client compiler default behavior for leaf directives: result 1`] = `
+"<div></div>
+<p>Leaf directive in a phrase ::NotALeafDirective</p>
+<p>::NotALeafDirective with a phrase after</p>"
+`;
+
+exports[`directives remark plugin - client compiler default behavior for text directives: console 1`] = `
+[
+  [
+    "[WARNING] Docusaurus found 2 unused Markdown directives in file "packages/docusaurus-mdx-loader/src/remark/unusedDirectives/__tests__/__fixtures__/textDirectives.md"
+- :textDirective3 (9:7)
+- :textDirective4 (11:7)
+Your content might render in an unexpected way. Visit https://github.com/facebook/docusaurus/pull/9394 to find out why and how to fix it.",
+  ],
+]
+`;
+
+exports[`directives remark plugin - client compiler default behavior for text directives: result 1`] = `
+"<p>Simple: textDirective1</p>
+<pre><code class="language-sh">Simple: textDirectiveCode
+</code></pre>
+<p>Simple:textDirective2</p>
+<p>Simple<div>label</div></p>
+<p>Simple<div></div></p>
+<p>Simple:textDirective5</p>
+<pre><code class="language-sh">Simple:textDirectiveCode
+</code></pre>"
+`;
+
+exports[`directives remark plugin - server compiler default behavior for container directives: result 1`] = `
+"<admonition type="danger"><p>Take care of snowstorms...</p></admonition>
+<div><p>unused directive content</p></div>
+<p>:::NotAContainerDirective with a phrase after</p>
+<p>:::</p>
+<p>Phrase before :::NotAContainerDirective</p>
+<p>:::</p>"
+`;
+
+exports[`directives remark plugin - server compiler default behavior for leaf directives: result 1`] = `
+"<div></div>
+<p>Leaf directive in a phrase ::NotALeafDirective</p>
+<p>::NotALeafDirective with a phrase after</p>"
+`;
+
+exports[`directives remark plugin - server compiler default behavior for text directives: result 1`] = `
+"<p>Simple: textDirective1</p>
+<pre><code class="language-sh">Simple: textDirectiveCode
+</code></pre>
+<p>Simple:textDirective2</p>
+<p>Simple<div>label</div></p>
+<p>Simple<div></div></p>
+<p>Simple:textDirective5</p>
+<pre><code class="language-sh">Simple:textDirectiveCode
+</code></pre>"
+`;