fix(v1): fenced block detection (#3340)

packages/docusaurus-1.x/lib/server/__tests__/utils.test.js

@@ -91,4 +91,20 @@ describe('server utils', () => {
     expect(utils.getSubDir(docE, docsDir)).toBeNull();
     expect(utils.getSubDir(docE, translatedDir)).toEqual('lol/lah');
   });
+
+  describe('replaceAssetsLink', () => {
+    test('verifies asset link is replaced after code block', () => {
+      const content = '```Some block```\n![alt](assets/my.png) more text';
+      const link = utils.replaceAssetsLink(content, 'thelocation');
+      expect(link).toBe(
+        '```Some block```\n![alt](thelocation/assets/my.png) more text',
+      );
+    });
+
+    test('verifies asset link is not replaced inside a fenced code block', () => {
+      const content = '```\n![alt](assets/my.png)\n```';
+      const link = utils.replaceAssetsLink(content, 'thelocation');
+      expect(link).toBe('```\n![alt](assets/my.png)\n```');
+    });
+  });
 });

packages/docusaurus-1.x/lib/server/utils.js

@@ -69,7 +69,7 @@ function autoPrefixCss(cssContent) {
 function replaceAssetsLink(oldContent, location) {
   let fencedBlock = false;
   const lines = oldContent.split('\n').map((line) => {
-    if (line.trim().startsWith('```')) {
+    if (line.trim().startsWith('```') && line.match(/`/g).length === 3) {
       fencedBlock = !fencedBlock;
     }
     return fencedBlock