What is the reason behind tests failing when run together in a group but passing individually in @playwright/test?

Answer

Possible Reasons for Test Failures

When tests pass individually but fail when run together in a group, it's often due to shared state or dependencies between tests. In @playwright/test, this can happen for several reasons:

1. Shared browser context or page: If you're reusing the same browser context or page across multiple tests, changes made in one test might affect others. To avoid this, create a new context and page for each test using test.beforeEach and test.afterEach hooks.

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

test.beforeEach(async ({ context }) => {
  await context.newPage();
});

test.afterEach(async ({ context }) => {
  await context.close();
});

test('Test 1', async ({ page }) => {
  await page.goto('https://ray.run/');
  // Perform test actions
});

test('Test 2', async ({ page }) => {
  await page.goto('https://ray.run/');
  // Perform test actions
});

2. Test order dependency: Ensure your tests are independent and can run in any order. Avoid relying on the outcome of a previous test for the next test to succeed.

3. Concurrency issues: When running tests in parallel, shared resources or race conditions might cause unexpected failures. Use test.serial to run tests sequentially if they depend on shared resources.

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

test.serial('Test 1', async ({ page }) => {
  await page.goto('https://ray.run/');
  // Perform test actions
});

test.serial('Test 2', async ({ page }) => {
  await page.goto('https://ray.run/');
  // Perform test actions
});

4. Timeouts: If your tests have long-running actions or network requests, consider increasing the default timeout to avoid test failures due to timeouts.

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

test.setTimeout(10000); // Set the timeout to 10 seconds

test('Test with increased timeout', async ({ page }) => {
  await page.goto('https://ray.run/');
  // Perform test actions
});

By addressing these issues, you can ensure your tests run reliably both individually and in groups. For more tips on writing efficient @playwright/test scripts, check out this blog post.