fix(v2): fix code block title parsing, support multiple metastring attributes (#4541)

* feat: lazy match classic theme code block title

* feat: allow single quotes for classic theme code block title

* refactor(v2): extract parseCodeBlockTitle function

extract `parseCodeBlockTitle` function to add tests for title parsing

* test(v2): add tests for parseCodeBlockTitle

* move code block title parser to theme-common

Co-authored-by: slorber <lorber.sebastien@gmail.com>

packages/docusaurus-theme-common/src/utils/__tests__/codeBlockUtils.test.ts

@@ -0,0 +1,54 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+import {parseCodeBlockTitle} from '../codeBlockUtils';
+
+describe('parseCodeBlockTitle', () => {
+  test('should parse double quote delimited title', () => {
+    expect(parseCodeBlockTitle(`title="index.js"`)).toEqual(`index.js`);
+  });
+
+  test('should parse single quote delimited title', () => {
+    expect(parseCodeBlockTitle(`title='index.js'`)).toEqual(`index.js`);
+  });
+
+  test('should not parse mismatched quote delimiters', () => {
+    expect(parseCodeBlockTitle(`title="index.js'`)).toEqual(``);
+  });
+
+  test('should parse undefined metastring', () => {
+    expect(parseCodeBlockTitle(undefined)).toEqual(``);
+  });
+
+  test('should parse metastring with no title specified', () => {
+    expect(parseCodeBlockTitle(`{1,2-3}`)).toEqual(``);
+  });
+
+  test('should parse with multiple metadatas title first', () => {
+    expect(parseCodeBlockTitle(`title="index.js" label="JavaScript"`)).toEqual(
+      `index.js`,
+    );
+  });
+
+  test('should parse with multiple metadatas title last', () => {
+    expect(parseCodeBlockTitle(`label="JavaScript" title="index.js"`)).toEqual(
+      `index.js`,
+    );
+  });
+
+  test('should parse double quotes when delimited by single quotes', () => {
+    expect(parseCodeBlockTitle(`title='console.log("Hello, World!")'`)).toEqual(
+      `console.log("Hello, World!")`,
+    );
+  });
+
+  test('should parse single quotes when delimited by double quotes', () => {
+    expect(parseCodeBlockTitle(`title="console.log('Hello, World!')"`)).toEqual(
+      `console.log('Hello, World!')`,
+    );
+  });
+});

packages/docusaurus-theme-common/src/utils/codeBlockUtils.ts

@@ -0,0 +1,12 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+const codeBlockTitleRegex = /title=(["'])(.*?)\1/;
+
+export function parseCodeBlockTitle(metastring?: string): string {
+  return metastring?.match(codeBlockTitleRegex)?.[2] ?? '';
+}