fix(mdx-loader): allow spaces before mdx-code-block info string (#9776)

packages/docusaurus-utils/src/__tests__/markdownUtils.test.ts

@@ -1251,6 +1251,38 @@ describe('unwrapMdxCodeBlocks', () => {
         </VersionsProvider>
     `);
   });
+
+  it('allow spaces before mdx-code-block info string', () => {
+    expect(
+      unwrapMdxCodeBlocks(dedent`
+        # Title
+
+        \`\`\` mdx-code-block
+        import Comp, {User} from "@site/components/comp"
+
+        <Comp prop="test">
+          <User user={{firstName: "Sébastien"}} />
+        </Comp>
+
+        export const age = 36
+        \`\`\`
+
+        text
+    `),
+    ).toEqual(dedent`
+        # Title
+
+        import Comp, {User} from "@site/components/comp"
+
+        <Comp prop="test">
+          <User user={{firstName: "Sébastien"}} />
+        </Comp>
+
+        export const age = 36
+
+        text
+    `);
+  });
 });
 
 describe('admonitionTitleToDirectiveLabel', () => {

packages/docusaurus-utils/src/markdownUtils.ts

@@ -70,9 +70,9 @@ export function escapeMarkdownHeadingIds(content: string): string {
 export function unwrapMdxCodeBlocks(content: string): string {
   // We only support 3/4 backticks on purpose, should be good enough
   const regexp3 =
-    /(?<begin>^|\n)```mdx-code-block\n(?<children>.*?)\n```(?<end>\n|$)/gs;
+    /(?<begin>^|\n)```(?<spaces>\x20*)mdx-code-block\n(?<children>.*?)\n```(?<end>\n|$)/gs;
   const regexp4 =
-    /(?<begin>^|\n)````mdx-code-block\n(?<children>.*?)\n````(?<end>\n|$)/gs;
+    /(?<begin>^|\n)````(?<spaces>\x20*)mdx-code-block\n(?<children>.*?)\n````(?<end>\n|$)/gs;
 
   // eslint-disable-next-line @typescript-eslint/no-explicit-any
   const replacer = (substring: string, ...args: any[]) => {