add unit tests for generateBlogData

Author: dario-piotrowicz

apps/site/next-data/generators/__tests__/blogData.test.mjs

@@ -0,0 +1,188 @@
+import { Readable } from 'node:stream';
+
+import generateBlogData from '@/next-data/generators/blogData.mjs';
+
+let files = [];
+
+jest.mock('node:path', () => ({
+  ...jest.requireActual('node:path'),
+  join: jest.fn((_base, filePath) => filePath),
+}));
+
+jest.mock('node:fs', () => {
+  const originalFs = jest.requireActual('node:fs');
+  return {
+    ...originalFs,
+    createReadStream: jest.fn(filename => {
+      const readable = new Readable();
+      const file = files.find(f => f.path === filename);
+      readable.push(`---\n`);
+      file.frontMatterContent.forEach(line => readable.push(`${line}\n`));
+      readable.push(`---\n`);
+      readable.push(null);
+      readable.close = () => {};
+      return readable;
+    }),
+  };
+});
+
+jest.mock('../../../next.helpers.mjs', () => {
+  const originalHelpers = jest.requireActual('../../../next.helpers.mjs');
+  return {
+    ...originalHelpers,
+    getMarkdownFiles: () => Promise.resolve(files.map(file => file.path)),
+  };
+});
+
+describe('generateBlogData', () => {
+  it('should return zero posts and only the default "all" category is no md file is found', async () => {
+    files = [];
+
+    const blogData = await generateBlogData();
+
+    expect(blogData.categories).toStrictEqual(['all']);
+    expect(blogData.posts).toStrictEqual([]);
+  });
+
+  it('should collect the data from a single md file if only one is found', async () => {
+    files = [
+      {
+        path: 'pages/en/blog/post1.md',
+        frontMatterContent: [
+          `date: '2020-01-01T00:00:00.000Z'`,
+          `title: POST 1`,
+          `author: author`,
+        ],
+      },
+    ];
+
+    const blogData = await generateBlogData();
+
+    expect(blogData.posts.length).toBe(1);
+    const post = blogData.posts[0];
+    expect(post.title).toEqual('POST 1');
+    expect(post.date).toEqual(new Date('2020-01-01T00:00:00.000Z'));
+    expect(post.author).toEqual('author');
+  });
+
+  it('should collect the data from multiple md files', async () => {
+    const currentDate = new Date();
+
+    files = [
+      {
+        path: 'pages/en/blog/post1.md',
+        frontMatterContent: [
+          `date: '2020-01-01T00:00:00.000Z'`,
+          `title: POST 1`,
+          `author: author-a`,
+        ],
+      },
+      {
+        path: 'pages/en/blog/post2.md',
+        frontMatterContent: [
+          `date: '2020-01-02T00:00:00.000Z'`,
+          `title: POST 2`,
+          `author: author-b`,
+        ],
+      },
+      {
+        path: 'pages/en/blog/post3.md',
+        frontMatterContent: [
+          // no date specified (the date defaults to the current date)
+          `title: POST 3`,
+          `author: author-c`,
+        ],
+      },
+    ];
+
+    const blogData = await generateBlogData();
+
+    expect(blogData.posts.length).toBe(3);
+    const post = blogData.posts[0];
+    expect(post.title).toEqual('POST 1');
+    expect(post.date).toEqual(new Date('2020-01-01T00:00:00.000Z'));
+    expect(post.author).toEqual('author-a');
+    const post1 = blogData.posts[1];
+    expect(post1.title).toEqual('POST 2');
+    expect(post1.date).toEqual(new Date('2020-01-02T00:00:00.000Z'));
+    expect(post1.author).toEqual('author-b');
+    const post2 = blogData.posts[2];
+    expect(post2.title).toEqual('POST 3');
+    expect(post2.date.setMilliseconds(0)).toEqual(
+      currentDate.setMilliseconds(0)
+    );
+    expect(post2.author).toEqual('author-c');
+  });
+
+  it('should generate categories based on the categories of md files and their years', async () => {
+    files = [
+      {
+        path: 'pages/en/blog/post1.md',
+        frontMatterContent: [
+          "date: '2020-01-01T00:00:00.000Z'",
+          'category: category-a',
+        ],
+      },
+      {
+        path: 'pages/en/blog/sub-dir/post2.md',
+        frontMatterContent: [
+          "date: '2020-01-02T00:00:00.000Z'",
+          'category: category-b',
+        ],
+      },
+      {
+        path: 'pages/en/blog/post3.md',
+        frontMatterContent: [
+          "date: '2021-03-13T00:00:00.000Z'",
+          // no category specified (it should be "uncategorized")
+        ],
+      },
+      {
+        path: 'pages/en/blog/post4.md',
+        frontMatterContent: [
+          // no date specified (the date defaults to the current date)
+          'category: category-b',
+        ],
+      },
+    ];
+
+    const blogData = await generateBlogData();
+
+    expect(blogData.categories.sort()).toStrictEqual([
+      'all',
+      'category-a',
+      'category-b',
+      'uncategorized',
+      'year-2020',
+      'year-2021',
+      `year-${new Date().getUTCFullYear()}`,
+    ]);
+  });
+
+  it('should generate slugs based on the md filenames and categories', async () => {
+    files = [
+      {
+        path: 'pages/en/blog/post1.md',
+        frontMatterContent: ['category: category-a'],
+      },
+      {
+        path: 'pages/en/blog/post2.md',
+        frontMatterContent: ['category: category-b'],
+      },
+      {
+        path: 'pages/en/blog/post3.md',
+        frontMatterContent: [
+          // no category specified
+        ],
+      },
+    ];
+
+    const blogData = await generateBlogData();
+
+    expect(blogData.posts.map(p => p.slug).sort()).toStrictEqual([
+      '/blog/category-a/post1',
+      '/blog/category-b/post2',
+      '/blog/uncategorized/post3',
+    ]);
+  });
+});