Don't replace static assets linking in fenced code blocks

lib/server/__tests__/__fixtures__/doc1.md

@@ -3,4 +3,14 @@ id: doc1
 title: Document 1
 ---
 
-Docusaurus is the best :)
+Docusaurus is the best :)
+
+![image1](assets/image1.png)
+
+```js
+console.log("Docusaurus");
+```
+
+![image2](assets/image2.jpg)
+![image3](assets/image3.gif)
+

lib/server/__tests__/__fixtures__/doc2.md

@@ -15,4 +15,15 @@ title: Document 2
 ## Repeating Docs
 
 - [doc1](doc1.md)
-- [doc2](./doc2.md)
+- [doc2](./doc2.md)
+
+## Do not replace this
+```md
+![image1](assets/image1.png)
+```
+
+```js
+const doc1 = foo();
+console.log("[image2](assets/image2.jpg)");
+const testStr = `![image3](assets/image3.gif)`;
+```

lib/server/__tests__/__snapshots__/docs.test.js.snap

@@ -2,7 +2,18 @@
 
 exports[`mdToHtmlify transform nothing 1`] = `
 "
-Docusaurus is the best :)"
+Docusaurus is the best :)
+
+![image1](assets/image1.png)
+
+\`\`\`js
+console.log(\\"Docusaurus\\");
+\`\`\`
+
+![image2](assets/image2.jpg)
+![image3](assets/image3.gif)
+
+"
 `;
 
 exports[`mdToHtmlify transform to correct link 1`] = `
@@ -19,5 +30,60 @@ exports[`mdToHtmlify transform to correct link 1`] = `
 ## Repeating Docs
 
 - [doc1](/docs/en/next/doc1)
-- [doc2](/docs/en/next/doc2)"
+- [doc2](/docs/en/next/doc2)
+
+## Do not replace this
+\`\`\`md
+![image1](assets/image1.png)
+\`\`\`
+
+\`\`\`js
+const doc1 = foo();
+console.log(\\"[image2](assets/image2.jpg)\\");
+const testStr = \`![image3](assets/image3.gif)\`;
+\`\`\`"
+`;
+
+exports[`replaceAssetsLink does not transform document without valid assets link 1`] = `
+"
+### Existing Docs
+
+- [doc1](doc1.md)
+- [doc2](./doc2.md)
+
+### Non-existing Docs
+
+- [hahaha](hahaha.md)
+
+## Repeating Docs
+
+- [doc1](doc1.md)
+- [doc2](./doc2.md)
+
+## Do not replace this
+\`\`\`md
+![image1](assets/image1.png)
+\`\`\`
+
+\`\`\`js
+const doc1 = foo();
+console.log(\\"[image2](assets/image2.jpg)\\");
+const testStr = \`![image3](assets/image3.gif)\`;
+\`\`\`"
+`;
+
+exports[`replaceAssetsLink transform document with valid assets link 1`] = `
+"
+Docusaurus is the best :)
+
+![image1](/docs/assets/image1.png)
+
+\`\`\`js
+console.log(\\"Docusaurus\\");
+\`\`\`
+
+![image2](/docs/assets/image2.jpg)
+![image3](/docs/assets/image3.gif)
+
+"
 `;

lib/server/__tests__/docs.test.js

@@ -49,9 +49,10 @@ const doc2 = fs.readFileSync(
   'utf8'
 );
 
+const rawContent1 = metadataUtils.extractMetadata(doc1).rawContent;
+const rawContent2 = metadataUtils.extractMetadata(doc2).rawContent;
+
 describe('mdToHtmlify', () => {
-  const rawContent1 = metadataUtils.extractMetadata(doc1).rawContent;
-  const rawContent2 = metadataUtils.extractMetadata(doc2).rawContent;
   const mdToHtml = metadataUtils.mdToHtml(Metadata, '/');
 
   test('transform nothing', () => {
@@ -129,6 +130,26 @@ describe('getFile', () => {
   });
 });
 
+describe('replaceAssetsLink', () => {
+  test('transform document with valid assets link', () => {
+    const content1 = docs.replaceAssetsLink(rawContent1);
+    expect(content1).toMatchSnapshot();
+    expect(content1).toContain('![image1](/docs/assets/image1.png)');
+    expect(content1).toContain('![image2](/docs/assets/image2.jpg)');
+    expect(content1).toContain('![image3](/docs/assets/image3.gif)');
+    expect(content1).not.toEqual(rawContent1);
+  });
+
+  test('does not transform document without valid assets link', () => {
+    const content2 = docs.replaceAssetsLink(rawContent2);
+    expect(content2).toMatchSnapshot();
+    expect(content2).not.toContain('![image1](/docs/assets/image1.png)');
+    expect(content2).not.toContain('![image2](/docs/assets/image2.jpg)');
+    expect(content2).not.toContain('![image3](/docs/assets/image3.gif)');
+    expect(content2).toEqual(rawContent2);
+  });
+});
+
 afterAll(() => {
   process.chdir(originalCwd);
 });

lib/server/docs.js

@@ -69,18 +69,25 @@ function mdToHtmlify(oldContent, mdToHtml, metadata) {
   return content;
 }
 
+function replaceAssetsLink(oldContent) {
+  return oldContent.replace(
+    /(^`{3}(?:[\S]+)\n[\s\S]*?)?(?:\]\(assets\/)([\s\S]*?\n`{3})?/gm,
+    (match, fenceBlockStart, fenceBlockEnd) =>
+      fenceBlockStart && fenceBlockEnd
+        ? match
+        : match.replace(/\]\(assets\//g, `](${siteConfig.baseUrl}docs/assets/`)
+  );
+}
+
 function getComponent(rawContent, mdToHtml, metadata) {
   // generate table of contents
   let content = insertTOC(rawContent);
 
   // replace any links to markdown files to their website html links
   content = mdToHtmlify(content, mdToHtml, metadata);
 
-  // replace any relative links to static assets to absolute links
-  content = content.replace(
-    /\]\(assets\//g,
-    `](${siteConfig.baseUrl}docs/assets/`
-  );
+  // replace any relative links to static assets (not in fenced code blocks) to absolute links
+  content = replaceAssetsLink(content);
 
   const DocsLayout = require('../core/DocsLayout.js');
   return (
@@ -97,4 +104,5 @@ module.exports = {
   getComponent,
   getFile,
   mdToHtmlify,
+  replaceAssetsLink,
 };