Test Generator

Test Generator

Generate tests for the given target.

Mode selection: If $0 is the literal token e2e, skip to the E2E Mode (Playwright) section at the bottom. Otherwise generate Vitest unit tests for the file per Steps 1–7 below.

Target: $ARGUMENTS Test framework: !cat package.json 2>/dev/null | grep -o '"vitest"' | head -1 || echo "vitest not found" Existing tests: !find src -name "*.test.ts" -o -name "*.test.tsx" -o -name "*.spec.ts" -o -name "*.spec.tsx" 2>/dev/null | head -10 || echo "none found"

Step 1: Analyze the Target File

Read $ARGUMENTS and extract:

• All exported functions, classes, components, and types
• Dependencies and imports (what needs mocking)
• Side effects (API calls, database queries, file system access)
• Input parameter types and return types

Step 2: Check for Existing Tests

Search for existing test files:

• <filename>.test.ts / <filename>.test.tsx
• <filename>.spec.ts / <filename>.spec.tsx
• __tests__/<filename>.ts

If tests exist, read them and only add missing coverage. Do NOT duplicate existing test cases.

Step 3: Identify Test Cases

For each export, determine:

Category	What to test
Happy path	Normal input produces expected output
Edge cases	Empty input, null/undefined, boundary values
Error paths	Invalid input, thrown errors, rejected promises
Async	Promise resolution/rejection, timeout behavior
Dependencies	Mock external calls (API, DB, third-party libs)

Step 4: Follow Existing Conventions

If existing test files were found in Step 2, match their:

• Import style (import { describe } from 'vitest' vs global)
• Mock patterns (vi.mock, vi.fn, vi.spyOn)
• File naming convention (.test.ts vs .spec.ts)
• Describe/it block structure
• Assertion style (expect().toBe(), expect().toEqual())

If no existing tests, use this default structure:

import { describe, it, expect, vi, beforeEach } from 'vitest';

Step 5: Generate Tests

Write the test file next to the source file (e.g., src/utils/calc.ts -> src/utils/calc.test.ts).

Rules:

• One describe block per exported function/component
• Descriptive test names: it('returns empty array when input is empty')
• Arrange-Act-Assert pattern in each test
• Mock external dependencies, never call real APIs/DB
• Test the public interface, not implementation details
• For React components: use @testing-library/react if available, otherwise test logic only

Step 6: Verify

Run the generated tests:

npx vitest run <test-file-path> --reporter=verbose

If tests fail:

• Read the error output
• Fix the test (not the source code)
• Re-run until all pass

Step 7: Summary

Output:

• Number of test cases generated
• Coverage areas: happy path, edge cases, error paths
• Any exports that were NOT tested (and why)
• Test run result: PASS / FAIL

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E2E Mode (Playwright)

Invoked as /test-gen e2e [flow description]. The remaining arguments after e2e describe the user flow to test (e.g. /test-gen e2e login flow). If no flow is given, generate tests for all critical paths (priority below).

E2E Step 1: Understand the Application

Identify:

• Routing setup (Next app/ routes or react-router config)
• Authentication flow (login page, auth guards)
• Main user-facing pages, form components and their validation
• API calls made during user flows

cat package.json | grep -o '"@playwright/test"' || echo "Playwright not installed"
ls playwright.config.* 2>/dev/null || echo "No Playwright config"
ls e2e/ tests/e2e/ tests/ 2>/dev/null | head -20

If Playwright is not installed:

npm install -D @playwright/test && npx playwright install chromium

E2E Step 2: Identify Critical User Flows

If no specific flow requested, prioritize:

1. Authentication — sign up, login, logout, password reset
2. Core CRUD — create, read, update, delete main entities
3. Navigation — landing page → key features → back
4. Error states — invalid form submission, 404 pages, unauthorized access
5. Payment/checkout — if applicable

E2E Step 3: Analyze Page Structure

For each page: read the component file, identify interactive elements, find data-testid attributes or accessible roles, trace triggered API calls, identify loading/success/error states.

E2E Step 4: Generate Tests

Create test files in the project's E2E directory (usually e2e/ or tests/e2e/). Follow Playwright best practices:

• Prefer accessible selectors: page.getByRole(), page.getByText(), page.getByTestId()
• page.waitForURL() for navigation, expect(page).toHaveURL() for route verification
• await expect(locator).toBeVisible() over waitForSelector
• Group related tests in test.describe() blocks
• test.beforeEach() for common setup (login, navigation)
• If a storageState auth fixture exists, use it for authenticated flows; otherwise log in via UI in beforeEach

Each test must assert meaningfully: URL changed, expected content visible, form feedback shown, data persists after reload where applicable.

E2E Step 5: Verify

npx playwright test <test-file> --reporter=list 2>&1

If tests fail: read the error output, fix the test (selectors, timing, assertions), re-run until passing.

E2E Step 6: Summary

Output:

• Files generated and flows covered
• Selector breakdown (roles / test IDs / text)
• Test run result: PASS / FAIL / SKIP with reasons
• Missing coverage and recommended data-testid additions