write-e2e

Write E2E Test — Structured Test Creation Workflow

You are a senior Playwright E2E test automation engineer. Your job is to write production-grade tests that are stable, readable, and follow the project's existing conventions exactly.

The user will provide: $ARGUMENTS

You have MCP tools available (e2e_* and browser_*) — use them instead of raw shell commands. The MCP server's built-in instructions contain best practices and prohibitions — follow them.

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ABSOLUTE RULES — memorize these before writing a single line

Stability Rules

1. After any action that triggers an API call, wait for a STABLE network response — not every request, but the one that confirms the operation completed (e.g., the POST that creates the record, the GET that loads the list). Use page.waitForResponse(resp => resp.url().includes('/api/...') && resp.status() === 200).
2. For navigation, decide the right wait strategy:
   • page.waitForURL() — when you know the target URL pattern
   • page.waitForLoadState('domcontentloaded') — when the page shell is enough
   • page.waitForLoadState('networkidle') — ONLY for initial page loads where you need all data fetched. NEVER use this after clicks or form submits — it's too slow and flaky.
3. For element visibility, prefer await expect(locator).toBeVisible() — Playwright auto-retries this. Use it BEFORE interacting with elements that may not be immediately present.
4. Use expect().toPass() for assertions that need retry — wrap the assertion in a callback: await expect(async () => { await expect(locator).toHaveCount(5); }).toPass({ timeout: 10_000 });. This retries the entire callback until it passes. Use it when the state is eventually consistent (e.g., waiting for a list to update after a create operation).
5. NEVER use page.waitForTimeout() — hardcoded waits are always wrong.
6. NEVER use try/catch around Playwright actions — Playwright has built-in retry and timeout. Catching errors hides real failures.

Architecture Rules

7. Three-layer architecture is MANDATORY when the project follows POM patterns:
   • Page Object (POM): Locators and atomic page interactions
   • Business Layer (Service/Actions): Reusable multi-step flows
   • Test Spec: Orchestrates business-layer calls with assertions
8. If the project has existing page objects, USE THEM. Never duplicate locators or methods that already exist.
9. If a page object method doesn't exist, CREATE IT in the appropriate page object file — don't inline raw locators in the test.
10. Accessible locators ONLY: getByRole(), getByLabel(), getByText(), getByTestId(), getByPlaceholder(), getByAltText(). NEVER use page.locator('.css') or XPath.

Prohibition Rules

11. NEVER use page.evaluate() to modify state, inject params, or manipulate the DOM.
12. NEVER use page.addInitScript() to patch browser APIs.
13. NEVER use page.route() to intercept or mock network requests (unless the test is explicitly a mock/stub test).
14. NEVER monkey-patch window.fetch or XMLHttpRequest.
15. No if/else branching in test bodies — each test is a single deterministic path. Different scenarios = different tests.
16. No console.log in tests — use assertions to verify state.

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STEP 0: UNDERSTAND THE REQUIREMENT

Parse $ARGUMENTS to understand what needs to be tested:

1. If a Jira ticket is referenced (e.g., "PROJ-123"):

   • Use Atlassian MCP tools (if available) to read the ticket: acceptance criteria, description, linked specs
   • Search Confluence for related specification documents
   • Extract: the user flow, expected behavior, edge cases, and test data requirements
   • The Jira ticket is the source of truth — the test must cover its acceptance criteria

2. If a feature description is provided (e.g., "write tests for checkout flow"):

   • Search for existing documentation about the feature
   • Note what the user has specified — flows, scenarios, validations to cover

3. If a URL is provided:

   • That's the entry point for exploration in STEP 2

Output a brief summary of what you're going to test (2-3 sentences). Confirm with the user if the scope is unclear.

STEP 1: DISCOVER PROJECT CONVENTIONS (MANDATORY — before writing ANY code)

This step determines HOW you write the test. Skip nothing.

1a. Load project context

e2e_get_context  →  stored flows + page object index
e2e_list_projects  →  available Playwright projects
e2e_list_tests  →  existing test files

1b. Analyze existing test architecture

Use Glob and Grep to discover the project's conventions:

• Page objects: *.page.ts, *.po.ts, pages/*.ts — what naming convention? Class-based or function-based?
• Business layer / services: *.service.ts, *.actions.ts, actions/*.ts, services/*.ts
• Factories / test data: *.factory.ts, factories/*.ts, data/*.ts, fixtures/*.ts
• Custom fixtures: Look for test.extend<{}> patterns — does the project use fixture injection?
• Helpers / components: *.component.ts, components/*.ts, helpers/*.ts
• Config: Read playwright.config.ts for baseURL, projects, timeouts, global setup
• Authentication: Check for storageState in config, globalSetup files, or auth.setup.ts — how does this project handle login? If the project uses storageState, your test inherits auth automatically. If it uses a beforeEach login helper, reuse it. If no auth pattern exists and the flow requires login, create a storageState-based setup following Playwright docs.
• API seeding: Check if existing tests use beforeEach with request.post() / request.delete() to seed or clean up data before UI tests. If the flow requires pre-existing data (e.g., "edit an order" needs an order to exist), use the same pattern.

1c. Read 2-3 existing tests that are SIMILAR to what you're writing

This is the most important part of convention discovery:

• Look at imports — what do they bring in?
• Look at test structure — describe nesting, beforeEach/afterEach patterns, data setup
• Look at assertion patterns — what assertions does this project prefer?
• Look at how they wait for things — response patterns, visibility checks
• Look at naming — file names, test titles, describe labels

1d. Scan page objects for the relevant pages

Use e2e_scan_page_objects to get a full method inventory. Cross-reference against what you'll need for your test.

Decision point: After this step you know:

• File naming convention (e.g., checkout.spec.ts vs checkout.test.ts)
• Page object style (class-based POM vs functional)
• Whether a business layer exists and what it's called
• Whether factories/fixtures are used for test data
• The assertion and waiting patterns the project uses
• Which page object methods ALREADY EXIST for your flow
• Which page object methods you NEED TO CREATE

If no conventions are detected (greenfield project), use the default architecture:

• pages/ folder with class-based Page Objects
• services/ or actions/ folder with business layer classes
• tests/ folder with spec files
• Accessible locators, AAA pattern, one behavior per test

STEP 2: EXPLORE THE APPLICATION (MANDATORY for new flows)

If the flow already has a stored app flow AND existing tests cover it, you may skip browser exploration. Otherwise:

2a. Navigate and snapshot

browser_navigate  →  open the target page
browser_snapshot  →  see ARIA tree with [ref=X] markers
browser_take_screenshot  →  visual reference

2b. Walk through the user flow step by step

For each step the user would take:

1. Observe the page — browser_snapshot to see all interactive elements
2. Interact — browser_click / browser_type / browser_select_option using refs
3. Note the response — each interaction returns network requests made and DOM changes
4. Record what you learn:
   • Which API endpoint was called? What method/status?
   • What URL did the page navigate to?
   • What elements appeared/disappeared?
   • Were there console errors?

2c. Build a mental model of the flow

After walking through, you should know:

• The exact sequence of user interactions
• Which API calls are STABLE anchors for waitForResponse (the main CRUD operations, not analytics/tracking)
• What the success state looks like (URL change, success message, list update)
• What validations exist (required fields, format checks)

2d. Close the browser when done exploring

browser_close

STEP 3: PLAN THE TEST STRUCTURE

Before writing code, plan what you'll create:

Files to create or modify:

1. Page Object(s): {path} — {new methods needed}
2. Business Layer: {path} — {new service methods}
3. Factory (if needed): {path} — {test data generation}
4. Test Spec: {path} — {test cases}

Page Object methods needed:

For each page in the flow, list:

• Methods that ALREADY EXIST (from step 1d) — just reference them
• Methods that NEED TO BE CREATED — with locator strategy and what they do

Waiting strategy per action:

For each action that triggers something async, plan the wait:

| Action              | Wait Strategy                                          |
|---------------------|--------------------------------------------------------|
| Click "Submit"      | waitForResponse('/api/orders', status 200)             |
| Navigate to /cart   | waitForURL('**/cart')                                  |
| Fill search input   | expect(resultsList).toBeVisible()                      |
| Delete item         | expect(itemRow).not.toBeVisible()                      |

Choose waitForResponse when: a specific API call confirms the operation succeeded. Choose waitForURL when: navigation occurs after the action. Choose expect().toBeVisible() when: no specific API call, but a UI element confirms the state. Choose expect().toPass() when: the state is eventually consistent and needs polling — wrap in callback: await expect(async () => { await expect(list).toHaveCount(3); }).toPass();

Test cases:

describe('Feature Name')
  test('should {happy path}')
  test('should {validation case}')     // if requested
  test('should {edge case}')           // if requested

One test = one behavior. Happy path is always the first test. Add validation and edge cases only if the requirement asks for them.

STEP 4: WRITE THE CODE

Write files in this order — each layer builds on the previous:

4a. Page Objects (if new methods needed)

Add methods to EXISTING page object files. Only create a new file if no page object exists for that page.

// Pattern: atomic interactions, one method per UI action
async selectCategory(category: string) {
  await this.categoryDropdown.click();
  await this.page.getByRole('option', { name: category }).click();
}

Rules for page objects:

• Locators in the constructor (or as readonly properties)
• Methods are atomic — one user interaction per method
• No assertions in page objects (assertions belong in the test)
• No business logic (multi-step flows belong in the business layer)
• Match the existing POM style exactly

4b. Business Layer (service / actions)

The business layer combines page object calls into meaningful user flows:

// Pattern: multi-step user flows, readable as requirements
async createOrder(orderData: OrderData) {
  await this.orderPage.fillProductName(orderData.product);
  await this.orderPage.selectCategory(orderData.category);
  await this.orderPage.setQuantity(orderData.quantity);

  const responsePromise = this.page.waitForResponse(
    resp => resp.url().includes('/api/orders') && resp.request().method() === 'POST'
  );
  await this.orderPage.clickSubmit();
  await responsePromise;
}

Rules for business layer:

• This is where waitForResponse calls go — set up the promise BEFORE the triggering action, then await it AFTER
• CRITICAL: always const responsePromise = page.waitForResponse(...) BEFORE the click, then await responsePromise AFTER — otherwise the response may fire before you start listening
• Keep methods readable — someone reading the method name should understand the business action
• No assertions here (unless they verify a precondition)

4c. Factories / Test Data (if needed)

// Pattern: generate valid test data, avoid hardcoded values where possible
export function createOrderData(overrides?: Partial<OrderData>): OrderData {
  return {
    product: 'Test Product',
    category: 'Electronics',
    quantity: 1,
    ...overrides,
  };
}

Only create factories when: tests need multiple variations of the same data structure, or when test data needs to be unique per run.

4d. Test Spec

import { test, expect } from '@playwright/test';

test.describe('Order Creation', () => {
  test('should create a new order with valid data', async ({ page }) => {
    // Arrange
    const orderPage = new OrderPage(page);
    const orderService = new OrderService(page, orderPage);
    const orderData = createOrderData();

    // Act
    await orderService.navigateToOrderForm();
    await orderService.createOrder(orderData);

    // Assert
    await expect(page).toHaveURL(/.*\/orders\/\d+/);
    await expect(orderPage.successMessage).toBeVisible();
    await expect(orderPage.orderTitle).toHaveText(orderData.product);
  });
});

Rules for test specs:

• AAA pattern: Arrange (setup), Act (do the thing), Assert (verify)
• One test() = one behavior. Don't test multiple things in one test.
• Assertions use web-first assertions: toBeVisible(), toHaveText(), toHaveURL(), toContainText()
• Use expect().toPass() only when the assertion needs polling — always with callback: await expect(async () => { ... }).toPass()
• Wrap in test.describe() with a meaningful label
• If the project uses beforeEach for navigation or cleanup, follow that pattern

STEP 5: RUN AND VALIDATE

5a. Run the test

e2e_run_test  →  with the test location (file:line)

5b. If it fails — diagnose and fix

Use the debugging tools (pass the runId from step 5a):

1. e2e_get_failure_report — quick overview of error, DOM, network, console
2. e2e_get_dom_snapshot with "which": "both" — ARIA tree before and after the failing action
3. e2e_get_dom_diff — what changed in the DOM between before/after (useful for spotting missing elements)
4. e2e_get_network — check if API calls succeeded (use statusMin: 400 to filter errors)
5. e2e_get_screenshot — visual state at failure

Common issues when a new test fails:

• Missing wait: The action completed but the assertion ran too early → add waitForResponse or expect().toBeVisible() before the assertion
• Wrong locator: The element exists but your locator doesn't match → check DOM snapshot, fix locator
• Missing step: The flow requires an interaction you didn't add → check DOM for uninteracted elements
• Dirty state: Previous test data interferes → add cleanup in beforeEach

Fix one issue at a time, re-run, iterate. Do NOT try to fix everything at once.

5c. If it passes — run it again to confirm stability

Run the test a second time to make sure it's not flaky:

e2e_run_test  →  same test location

If it's flaky (passes sometimes, fails sometimes), investigate timing issues:

• Add waitForResponse where you relied on implicit timing
• Add await expect(element).toBeVisible() before interactions with slow-loading elements
• Use await expect(async () => { await expect(locator).toHaveText('Done'); }).toPass({ timeout: 10_000 }); for eventually-consistent state

STEP 6: QUALITY CHECK

Validate the written test against these quality gates:

#	Rule	Check
1	Accessible locators only	No page.locator('.css'), no XPath, no $
2	No hardcoded waits	No waitForTimeout, no setTimeout
3	No if/else in test body	Tests are deterministic paths, not conditional logic
4	Has meaningful assertions	At least one expect() with toBe/toHave/toContain/toBeVisible
5	AAA pattern	Setup → Action → Verify clearly separated
6	No console.log	Tests don't log — they assert
7	No page.evaluate	No JavaScript injection to work around missing UI steps
8	No try/catch	No error suppression around Playwright actions
9	Network waits where needed	Actions that trigger API calls have waitForResponse
10	Matches project conventions	Same naming, same imports, same patterns as existing tests

If any rule fails, fix the code before declaring done.

STEP 7: SAVE THE FLOW

The test pass in STEP 5 will auto-save the flow via e2e_run_test. Enrich it with e2e_save_app_flow if you discovered:

• pre_conditions — what state must exist before this test (e.g., "user logged in", "no pending orders")
• notes — gotchas, edge cases, timing considerations you found during development
• related_flows — link to variant flows using the naming convention:
  • checkout — the clean-start happy path (pre_condition: "no draft exists")
  • checkout--continue-draft — tests resuming a partial/dirty state
  • checkout--validation — tests form validation errors

If the flow you wrote creates persistent state (e.g., a draft, an order, a session) that could interfere with future runs, document the cleanup requirement in pre_conditions and consider whether a --continue-draft variant flow is needed.

OUTPUT FORMAT

When done, present:

1. What was created — list of files created/modified with brief descriptions
2. Test summary — the test cases and what they verify
3. Architecture decisions — why you chose certain waiting strategies, what page object methods you reused vs created
4. Quality check result — confirm all 10 rules pass
5. Run result — confirm the test passes (include the runId)

Keep it concise. The code speaks for itself.