27. Data-Driven Testing & Dynamic Parameterization

1. Parameterized Tests with Arrays

Loop over test data items to generate distinct tests at compile-time:

import { test, expect } from "@playwright/test";
const searchScenarios = [
  { query: "Playwright", expectedCount: 15 },
  { query: "TypeScript", expectedCount: 25 },
  { query: "Selenium", expectedCount: 8 },
];
for (const { query, expectedCount } of searchScenarios) {
  test(search for "${query}" returns at least ${expectedCount} results, async ({ page }) => {
    await page.goto("/search");
    await page.getByPlaceholder("Search").fill(query);
    await page.keyboard.press("Enter");
const results = page.locator(".result-card");
    await expect(results).toHaveCount(expectedCount);
  });
}

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2. Loading Static JSON Test Fixtures

import usersData from "../data/users.json";
for (const user of usersData) {
  test(validate permissions for role ${user.role}, async ({ page }) => {
    // executes per user row
  });
}

---

3. Generating Unique Random Data

Avoid collision in parallel runs by generating dynamic emails and names:

export function generateTestCustomer() {
  const uniqueId = Date.now();
  return {
    name: Customer ${uniqueId},
    email: customer_${uniqueId}@testcompany.com,
    creditCardEnding: "4242",
  };
}