feat: report bundle size delta

.github/scripts/__tests__/post-bundle-comment.test.mts

@@ -0,0 +1,189 @@
+import { describe, it, beforeEach } from 'node:test';
+import assert from 'node:assert/strict';
+import { writeFileSync, mkdirSync, rmSync } from 'node:fs';
+import { join } from 'node:path';
+import { tmpdir } from 'node:os';
+import { createRequire } from 'node:module';
+
+const require = createRequire(import.meta.url);
+const postBundleComment = require('../post-bundle-comment.js') as (args: {
+  github: ReturnType<typeof makeGithub>['github'];
+  context: ReturnType<typeof makeContext>;
+  reportPath?: string;
+}) => Promise<void>;
+
+const marker = '<!-- bundle-size-report -->';
+
+let tmpDir: string;
+let reportPath: string;
+
+beforeEach(() => {
+  tmpDir = join(tmpdir(), `post-bundle-test-${Date.now()}`);
+  mkdirSync(tmpDir, { recursive: true });
+  reportPath = join(tmpDir, 'report.md');
+  writeFileSync(reportPath, '## Bundle Size Report\n\nSome content here.');
+});
+
+interface Comment {
+  id: number;
+  body: string;
+}
+
+interface GithubCalls {
+  create: object[];
+  update: object[];
+  list: object[];
+}
+
+// Helper to create a mock github object and record calls
+function makeGithub(existingComments: Comment[] = []) {
+  const calls: GithubCalls = { create: [], update: [], list: [] };
+  const github = {
+    rest: {
+      issues: {
+        listComments: async (args: object) => {
+          calls.list.push(args);
+          return { data: existingComments };
+        },
+        createComment: async (args: object) => {
+          calls.create.push(args);
+        },
+        updateComment: async (args: object) => {
+          calls.update.push(args);
+        },
+      },
+    },
+  };
+  return { github, calls };
+}
+
+function makeContext({ owner = 'test-owner', repo = 'test-repo', number = 42 } = {}) {
+  return {
+    repo: { owner, repo },
+    issue: { number },
+  };
+}
+
+describe('post-bundle-comment', () => {
+  it('creates a new comment when no existing comment contains the marker', async () => {
+    const { github, calls } = makeGithub([]);
+    await postBundleComment({ github, context: makeContext(), reportPath });
+
+    assert.equal(calls.create.length, 1, 'Should create exactly one comment');
+    assert.equal(calls.update.length, 0, 'Should not update any comment');
+  });
+
+  it('updates existing comment when marker found', async () => {
+    const existing = { id: 99, body: `${marker}\nOld content` };
+    const { github, calls } = makeGithub([existing]);
+    await postBundleComment({ github, context: makeContext(), reportPath });
+
+    assert.equal(calls.update.length, 1, 'Should update exactly one comment');
+    assert.equal(calls.create.length, 0, 'Should not create a new comment');
+    assert.equal((calls.update[0] as { comment_id: number }).comment_id, 99, 'Should update the correct comment by id');
+  });
+
+  it('body always starts with marker and newline', async () => {
+    const { github, calls } = makeGithub([]);
+    await postBundleComment({ github, context: makeContext(), reportPath });
+
+    const body = (calls.create[0] as { body: string }).body;
+
+    assert.ok(body.startsWith(`${marker}\n`), `Body should start with marker, got: ${body.slice(0, 50)}`);
+  });
+
+  it('updated comment body also starts with marker and newline', async () => {
+    const existing = { id: 7, body: `${marker}\nStale content` };
+    const { github, calls } = makeGithub([existing]);
+    await postBundleComment({ github, context: makeContext(), reportPath });
+
+    const body = (calls.update[0] as { body: string }).body;
+
+    assert.ok(body.startsWith(`${marker}\n`));
+  });
+
+  it('includes report file content in the comment body', async () => {
+    const { github, calls } = makeGithub([]);
+    await postBundleComment({ github, context: makeContext(), reportPath });
+
+    const body = (calls.create[0] as { body: string }).body;
+
+    assert.ok(body.includes('## Bundle Size Report'), 'Should include report heading');
+    assert.ok(body.includes('Some content here.'), 'Should include report body content');
+  });
+
+  it('reads report from a custom reportPath', async () => {
+    const customPath = join(tmpDir, 'custom.md');
+
+    writeFileSync(customPath, 'Custom report content for testing!');
+
+    const { github, calls } = makeGithub([]);
+    await postBundleComment({ github, context: makeContext(), reportPath: customPath });
+
+    assert.ok((calls.create[0] as { body: string }).body.includes('Custom report content for testing!'));
+  });
+
+  it('passes correct owner, repo, issue_number from context to listComments', async () => {
+    const { github, calls } = makeGithub([]);
+    await postBundleComment({
+      github,
+      context: makeContext({ owner: 'my-org', repo: 'my-repo', number: 123 }),
+      reportPath,
+    });
+
+    assert.equal((calls.list[0] as { owner: string }).owner, 'my-org');
+    assert.equal((calls.list[0] as { repo: string }).repo, 'my-repo');
+    assert.equal((calls.list[0] as { issue_number: number }).issue_number, 123);
+  });
+
+  it('passes correct owner, repo, issue_number from context to createComment', async () => {
+    const { github, calls } = makeGithub([]);
+    await postBundleComment({
+      github,
+      context: makeContext({ owner: 'my-org', repo: 'my-repo', number: 123 }),
+      reportPath,
+    });
+
+    assert.equal((calls.create[0] as { owner: string }).owner, 'my-org');
+    assert.equal((calls.create[0] as { repo: string }).repo, 'my-repo');
+    assert.equal((calls.create[0] as { issue_number: number }).issue_number, 123);
+  });
+
+  it('passes correct owner and repo to updateComment', async () => {
+    const existing = { id: 55, body: `${marker}\nOld` };
+    const { github, calls } = makeGithub([existing]);
+    await postBundleComment({
+      github,
+      context: makeContext({ owner: 'org2', repo: 'repo2', number: 7 }),
+      reportPath,
+    });
+
+    assert.equal((calls.update[0] as { owner: string }).owner, 'org2');
+    assert.equal((calls.update[0] as { repo: string }).repo, 'repo2');
+  });
+
+  it('uses the first comment that contains the marker (not just exact match)', async () => {
+    const comments = [
+      { id: 1, body: 'Just a regular comment' },
+      { id: 2, body: `${marker}\nFirst bundle report` },
+      { id: 3, body: `${marker}\nSecond bundle report` },
+    ];
+    const { github, calls } = makeGithub(comments);
+    await postBundleComment({ github, context: makeContext(), reportPath });
+
+    assert.equal(calls.update.length, 1);
+    assert.equal((calls.update[0] as { comment_id: number }).comment_id, 2, 'Should update the first matching comment');
+  });
+
+  it('creates comment when existing comments do not contain the marker', async () => {
+    const comments = [
+      { id: 10, body: 'No marker here' },
+      { id: 11, body: 'Also no marker' },
+    ];
+    const { github, calls } = makeGithub(comments);
+    await postBundleComment({ github, context: makeContext(), reportPath });
+
+    assert.equal(calls.create.length, 1);
+    assert.equal(calls.update.length, 0);
+  });
+});