Add missing unit tests for core modules

README.md

@@ -527,6 +527,19 @@ See [CLAUDE.md](CLAUDE.md) for repo structure and contributor notes.
 
 ---
 
+## Diff truncation
+
+Large diffs are automatically truncated before being sent to the LLM to stay within reasonable token budgets:
+
+| Stage | Character limit | Purpose |
+|---|---|---|
+| Change summarizer | 8 000 chars | Analyzing what changed and suggesting a demo flow |
+| Script generator | 10 000 chars | Generating the Playwright interaction script |
+
+When a diff exceeds the limit, it is cut at the threshold and a `... (diff truncated)` marker is appended so the LLM knows the input is incomplete. In practice this means very large PRs may produce less accurate scripts — consider using `routeMap` or `app.hint` to give the LLM additional context when working with big diffs.
+
+---
+
 ## Known limitations
 
 - **Single entry point** — only one preview URL or start command per run is supported; multiple entry points are planned.

packages/core/src/publisher/github-comment.ts

@@ -103,7 +103,7 @@ async function findExistingComment(
   return existing ? { id: existing.id } : null;
 }
 
-function buildCommentBody(options: CommentOptions): string {
+export function buildCommentBody(options: CommentOptions): string {
   const { analysis, recordingUrl, screenshots, script, rerunUrl } = options;
 
   const changedFilesList = analysis.changedFiles

tests/unit/change-summarizer.test.ts

@@ -0,0 +1,143 @@
+import { describe, it, expect, vi } from 'vitest';
+import { summarizeChanges } from '../../packages/core/src/analyzer/change-summarizer.js';
+import type { ParsedDiff } from '../../packages/core/src/analyzer/diff-parser.js';
+import type { RouteMapping } from '../../packages/core/src/analyzer/route-detector.js';
+
+function makeMockClient(responseText: string) {
+  return {
+    messages: {
+      create: vi.fn().mockResolvedValue({
+        content: [{ type: 'text', text: responseText }],
+      }),
+    },
+  } as any;
+}
+
+const SAMPLE_DIFF: ParsedDiff = {
+  files: [
+    { path: 'app/routes/home.tsx', changeType: 'modified', hunks: [], additions: 5, deletions: 2 },
+    { path: 'src/components/Button.tsx', changeType: 'added', hunks: [], additions: 20, deletions: 0 },
+  ],
+  rawDiff: 'diff --git a/app/routes/home.tsx ...',
+};
+
+const SAMPLE_ROUTES: RouteMapping[] = [
+  { file: 'app/routes/home.tsx', route: '/', changeType: 'modified' },
+];
+
+describe('summarizeChanges', () => {
+  it('returns parsed description and demo flow from valid JSON response', async () => {
+    const client = makeMockClient(JSON.stringify({
+      description: 'Added a new button component',
+      demoFlow: '1. Go to home\n2. Click the button',
+    }));
+
+    const result = await summarizeChanges(client, SAMPLE_DIFF, SAMPLE_ROUTES, 'claude-sonnet-4-6');
+
+    expect(result.changedFiles).toEqual(['app/routes/home.tsx', 'src/components/Button.tsx']);
+    expect(result.affectedRoutes).toEqual(SAMPLE_ROUTES);
+    expect(result.changeDescription).toBe('Added a new button component');
+    expect(result.suggestedDemoFlow).toBe('1. Go to home\n2. Click the button');
+  });
+
+  it('returns defaults when LLM response is not valid JSON', async () => {
+    const client = makeMockClient('This is not JSON at all');
+
+    const result = await summarizeChanges(client, SAMPLE_DIFF, SAMPLE_ROUTES, 'claude-sonnet-4-6');
+
+    expect(result.changeDescription).toBe('UI changes detected.');
+    expect(result.suggestedDemoFlow).toBe('Navigate to the affected page and interact with the changes.');
+  });
+
+  it('returns defaults when JSON is missing fields', async () => {
+    const client = makeMockClient(JSON.stringify({ unrelated: true }));
+
+    const result = await summarizeChanges(client, SAMPLE_DIFF, SAMPLE_ROUTES, 'claude-sonnet-4-6');
+
+    expect(result.changeDescription).toBe('UI changes detected.');
+    expect(result.suggestedDemoFlow).toBe('Navigate to the affected page and interact with the changes.');
+  });
+
+  it('extracts JSON embedded in surrounding text', async () => {
+    const client = makeMockClient(
+      'Here is the analysis:\n```json\n{"description": "Modal added", "demoFlow": "Open modal"}\n```'
+    );
+
+    const result = await summarizeChanges(client, SAMPLE_DIFF, SAMPLE_ROUTES, 'claude-sonnet-4-6');
+
+    expect(result.changeDescription).toBe('Modal added');
+    expect(result.suggestedDemoFlow).toBe('Open modal');
+  });
+
+  it('truncates large diffs before sending to LLM', async () => {
+    const client = makeMockClient(JSON.stringify({
+      description: 'Changes',
+      demoFlow: 'Demo',
+    }));
+    const largeDiff: ParsedDiff = {
+      files: SAMPLE_DIFF.files,
+      rawDiff: 'x'.repeat(10000),
+    };
+
+    await summarizeChanges(client, largeDiff, SAMPLE_ROUTES, 'claude-sonnet-4-6');
+
+    const prompt = client.messages.create.mock.calls[0][0].messages[0].content;
+    expect(prompt).toContain('(diff truncated)');
+    // The prompt should contain a truncated diff, not the full 10k chars
+    expect(prompt.length).toBeLessThan(10000);
+  });
+
+  it('does not truncate short diffs', async () => {
+    const client = makeMockClient(JSON.stringify({
+      description: 'Changes',
+      demoFlow: 'Demo',
+    }));
+
+    await summarizeChanges(client, SAMPLE_DIFF, SAMPLE_ROUTES, 'claude-sonnet-4-6');
+
+    const prompt = client.messages.create.mock.calls[0][0].messages[0].content;
+    expect(prompt).not.toContain('(diff truncated)');
+  });
+
+  it('includes route list in prompt when routes are provided', async () => {
+    const client = makeMockClient(JSON.stringify({ description: 'd', demoFlow: 'f' }));
+
+    await summarizeChanges(client, SAMPLE_DIFF, SAMPLE_ROUTES, 'claude-sonnet-4-6');
+
+    const prompt = client.messages.create.mock.calls[0][0].messages[0].content;
+    expect(prompt).toContain('app/routes/home.tsx');
+    expect(prompt).toContain('/');
+  });
+
+  it('shows fallback when no routes are detected', async () => {
+    const client = makeMockClient(JSON.stringify({ description: 'd', demoFlow: 'f' }));
+
+    await summarizeChanges(client, SAMPLE_DIFF, [], 'claude-sonnet-4-6');
+
+    const prompt = client.messages.create.mock.calls[0][0].messages[0].content;
+    expect(prompt).toContain('no routes detected automatically');
+  });
+
+  it('passes the specified model to the client', async () => {
+    const client = makeMockClient(JSON.stringify({ description: 'd', demoFlow: 'f' }));
+
+    await summarizeChanges(client, SAMPLE_DIFF, SAMPLE_ROUTES, 'claude-opus-4-6');
+
+    expect(client.messages.create).toHaveBeenCalledWith(
+      expect.objectContaining({ model: 'claude-opus-4-6' })
+    );
+  });
+
+  it('handles empty content response from LLM', async () => {
+    const client = {
+      messages: {
+        create: vi.fn().mockResolvedValue({ content: [] }),
+      },
+    } as any;
+
+    const result = await summarizeChanges(client, SAMPLE_DIFF, SAMPLE_ROUTES, 'claude-sonnet-4-6');
+
+    expect(result.changeDescription).toBe('UI changes detected.');
+    expect(result.suggestedDemoFlow).toBe('Navigate to the affected page and interact with the changes.');
+  });
+});

tests/unit/defaults.test.ts

@@ -0,0 +1,52 @@
+import { describe, it, expect } from 'vitest';
+import { DEFAULT_RECORDING, DEFAULT_LLM, DEFAULT_TRIGGER } from '../../packages/core/src/config/defaults.js';
+
+describe('DEFAULT_RECORDING', () => {
+  it('has expected viewport dimensions', () => {
+    expect(DEFAULT_RECORDING.viewport).toEqual({ width: 1280, height: 720 });
+  });
+
+  it('defaults to gif format', () => {
+    expect(DEFAULT_RECORDING.format).toBe('gif');
+  });
+
+  it('has 30 second max duration', () => {
+    expect(DEFAULT_RECORDING.maxDuration).toBe(30);
+  });
+
+  it('has 2x device scale factor for retina', () => {
+    expect(DEFAULT_RECORDING.deviceScaleFactor).toBe(2);
+  });
+
+  it('enables mouse click overlay by default', () => {
+    expect(DEFAULT_RECORDING.showMouseClicks).toBe(true);
+  });
+});
+
+describe('DEFAULT_LLM', () => {
+  it('uses anthropic provider', () => {
+    expect(DEFAULT_LLM.provider).toBe('anthropic');
+  });
+
+  it('uses claude-sonnet-4-6 model', () => {
+    expect(DEFAULT_LLM.model).toBe('claude-sonnet-4-6');
+  });
+});
+
+describe('DEFAULT_TRIGGER', () => {
+  it('uses auto mode', () => {
+    expect(DEFAULT_TRIGGER.mode).toBe('auto');
+  });
+
+  it('has threshold of 5', () => {
+    expect(DEFAULT_TRIGGER.threshold).toBe(5);
+  });
+
+  it('uses /glimpse as comment command', () => {
+    expect(DEFAULT_TRIGGER.commentCommand).toBe('/glimpse');
+  });
+
+  it('enables skip comment by default', () => {
+    expect(DEFAULT_TRIGGER.skipComment).toBe(true);
+  });
+});

tests/unit/github-comment.test.ts

@@ -0,0 +1,111 @@
+import { describe, it, expect } from 'vitest';
+import { buildCommentBody } from '../../packages/core/src/publisher/github-comment.js';
+import type { ChangeAnalysis } from '../../packages/core/src/analyzer/change-summarizer.js';
+
+describe('buildCommentBody', () => {
+  const ANALYSIS: ChangeAnalysis = {
+    changedFiles: ['app/routes/home.tsx', 'src/components/Button.tsx'],
+    affectedRoutes: [{ file: 'app/routes/home.tsx', route: '/', changeType: 'modified' }],
+    changeDescription: 'Added a virtual try-on button',
+    suggestedDemoFlow: '1. Navigate to home page\n2. Click try-on button',
+  };
+
+  it('includes comment marker for idempotent updates', () => {
+    const body = buildCommentBody({ analysis: ANALYSIS, script: 'demo()', owner: 'o', repo: 'r', pullNumber: 1 });
+    expect(body).toContain('<!-- git-glimpse-demo -->');
+  });
+
+  it('includes recording URL as image when provided', () => {
+    const body = buildCommentBody({
+      analysis: ANALYSIS,
+      recordingUrl: 'https://example.com/demo.gif',
+      script: 'demo()',
+      owner: 'o', repo: 'r', pullNumber: 1,
+    });
+    expect(body).toContain('![Demo](https://example.com/demo.gif)');
+    expect(body).toContain('Open it directly');
+  });
+
+  it('includes screenshots when no recording URL', () => {
+    const body = buildCommentBody({
+      analysis: ANALYSIS,
+      screenshots: ['https://example.com/s1.png', 'https://example.com/s2.png'],
+      script: 'demo()',
+      owner: 'o', repo: 'r', pullNumber: 1,
+    });
+    expect(body).toContain('Screenshot 1');
+    expect(body).toContain('Screenshot 2');
+    expect(body).not.toContain('No recording available');
+  });
+
+  it('shows fallback when neither recording nor screenshots are present', () => {
+    const body = buildCommentBody({ analysis: ANALYSIS, script: 'demo()', owner: 'o', repo: 'r', pullNumber: 1 });
+    expect(body).toContain('No recording available');
+  });
+
+  it('truncates file list to 5 and shows count of remaining', () => {
+    const manyFilesAnalysis: ChangeAnalysis = {
+      ...ANALYSIS,
+      changedFiles: ['a.tsx', 'b.tsx', 'c.tsx', 'd.tsx', 'e.tsx', 'f.tsx', 'g.tsx'],
+    };
+    const body = buildCommentBody({ analysis: manyFilesAnalysis, script: 'demo()', owner: 'o', repo: 'r', pullNumber: 1 });
+    expect(body).toContain('`a.tsx`');
+    expect(body).toContain('`e.tsx`');
+    expect(body).not.toContain('`f.tsx`');
+    expect(body).toContain('+2 more');
+  });
+
+  it('shows all files when 5 or fewer', () => {
+    const body = buildCommentBody({ analysis: ANALYSIS, script: 'demo()', owner: 'o', repo: 'r', pullNumber: 1 });
+    expect(body).toContain('`app/routes/home.tsx`');
+    expect(body).toContain('`src/components/Button.tsx`');
+    expect(body).not.toContain('more');
+  });
+
+  it('includes the change description', () => {
+    const body = buildCommentBody({ analysis: ANALYSIS, script: 'demo()', owner: 'o', repo: 'r', pullNumber: 1 });
+    expect(body).toContain('Added a virtual try-on button');
+  });
+
+  it('wraps script in collapsible details with typescript code block', () => {
+    const body = buildCommentBody({ analysis: ANALYSIS, script: 'export async function demo(page) {}', owner: 'o', repo: 'r', pullNumber: 1 });
+    expect(body).toContain('<details>');
+    expect(body).toContain('Demo script (auto-generated)');
+    expect(body).toContain('```typescript');
+    expect(body).toContain('export async function demo(page) {}');
+  });
+
+  it('includes rerun link when provided', () => {
+    const body = buildCommentBody({
+      analysis: ANALYSIS,
+      script: 'demo()',
+      rerunUrl: 'https://github.com/owner/repo/actions/runs/123',
+      owner: 'o', repo: 'r', pullNumber: 1,
+    });
+    expect(body).toContain('Re-run demo');
+    expect(body).toContain('https://github.com/owner/repo/actions/runs/123');
+  });
+
+  it('omits rerun link when not provided', () => {
+    const body = buildCommentBody({ analysis: ANALYSIS, script: 'demo()', owner: 'o', repo: 'r', pullNumber: 1 });
+    expect(body).not.toContain('Re-run demo');
+  });
+
+  it('includes git-glimpse branding', () => {
+    const body = buildCommentBody({ analysis: ANALYSIS, script: 'demo()', owner: 'o', repo: 'r', pullNumber: 1 });
+    expect(body).toContain('git-glimpse');
+    expect(body).toContain('logo_square_small.png');
+  });
+
+  it('prefers recording URL over screenshots', () => {
+    const body = buildCommentBody({
+      analysis: ANALYSIS,
+      recordingUrl: 'https://example.com/demo.gif',
+      screenshots: ['https://example.com/s1.png'],
+      script: 'demo()',
+      owner: 'o', repo: 'r', pullNumber: 1,
+    });
+    expect(body).toContain('![Demo]');
+    expect(body).not.toContain('Screenshot 1');
+  });
+});