feat: upgrade to MDX v2 (#8288)

Co-authored-by: Armano <armano2@users.noreply.github.com>

packages/docusaurus-mdx-loader/src/__tests__/frontMatter.test.ts

@@ -0,0 +1,93 @@
+/**
+ * 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 escapeStringRegexp from 'escape-string-regexp';
+import {
+  validateMDXFrontMatter,
+  DefaultMDXFrontMatter,
+  type MDXFrontMatter,
+} from '../frontMatter';
+
+function testField(params: {
+  prefix: string;
+  validFrontMatters: MDXFrontMatter[];
+  convertibleFrontMatter?: [
+    ConvertibleFrontMatter: {[key: string]: unknown},
+    ConvertedFrontMatter: MDXFrontMatter,
+  ][];
+  invalidFrontMatters?: [
+    InvalidFrontMatter: {[key: string]: unknown},
+    ErrorMessage: string,
+  ][];
+}) {
+  // eslint-disable-next-line jest/require-top-level-describe
+  test(`[${params.prefix}] accept valid values`, () => {
+    params.validFrontMatters.forEach((frontMatter) => {
+      expect(validateMDXFrontMatter(frontMatter)).toEqual(frontMatter);
+    });
+  });
+
+  // eslint-disable-next-line jest/require-top-level-describe
+  test(`[${params.prefix}] convert valid values`, () => {
+    params.convertibleFrontMatter?.forEach(
+      ([convertibleFrontMatter, convertedFrontMatter]) => {
+        expect(validateMDXFrontMatter(convertibleFrontMatter)).toEqual(
+          convertedFrontMatter,
+        );
+      },
+    );
+  });
+
+  // eslint-disable-next-line jest/require-top-level-describe
+  test(`[${params.prefix}] throw error for values`, () => {
+    params.invalidFrontMatters?.forEach(([frontMatter, message]) => {
+      try {
+        validateMDXFrontMatter(frontMatter);
+        throw new Error(
+          `MDX front matter is expected to be rejected, but was accepted successfully:\n ${JSON.stringify(
+            frontMatter,
+            null,
+            2,
+          )}`,
+        );
+      } catch (err) {
+        // eslint-disable-next-line jest/no-conditional-expect
+        expect((err as Error).message).toMatch(
+          new RegExp(escapeStringRegexp(message)),
+        );
+      }
+    });
+  });
+}
+
+describe('MDX front matter schema', () => {
+  it('accepts empty object', () => {
+    const frontMatter: Partial<MDXFrontMatter> = {};
+    expect(validateMDXFrontMatter(frontMatter)).toEqual(DefaultMDXFrontMatter);
+  });
+
+  it('accepts undefined object', () => {
+    expect(validateMDXFrontMatter(undefined)).toEqual(DefaultMDXFrontMatter);
+  });
+
+  it('rejects unknown field', () => {
+    const frontMatter = {abc: '1'};
+    expect(() =>
+      validateMDXFrontMatter(frontMatter),
+    ).toThrowErrorMatchingInlineSnapshot(`""abc" is not allowed"`);
+  });
+});
+
+describe('validateDocFrontMatter format', () => {
+  testField({
+    prefix: 'format',
+    validFrontMatters: [{format: 'md'}, {format: 'mdx'}],
+    invalidFrontMatters: [
+      [{format: 'xdm'}, '"format" must be one of [md, mdx, detect]'],
+    ],
+  });
+});