docs(testing): update testing instructions for debugging tests (#29800)

Adds more information to the testing documentation on how to execute
individual tests or pause execution.

docs/core/testing/usage-instructions.md

@@ -138,6 +138,70 @@ npm run test.e2e src/components/chip
  npm run test.e2e src/components/chip -- --headed
  ```
 
+### Debugging Tests
+
+Playwright offers several ways to efficiently isolate and debug specific issues, helping to quickly identify and resolve problems within your test suite.
+
+#### 1. Running Only Individual Tests
+
+The `.only` suffix can be added to individual tests to limit execution to just those tests during debugging. If you add `.only` to a specific test, only that test will be executed, and all other tests in the test suite will be skipped.
+
+**Example:**
+
+```ts
+test.only('should do something', async ({ page }) => {
+  // test code here
+});
+```
+
+> [!IMPORTANT]
+> After debugging, make sure to remove the `.only` suffix to ensure all tests run again during normal execution.
+
+#### 2. Running Only a Test Suite
+
+Similarly, you can focus on an entire test suite by adding `.only` to a `describe` block. This ensures that only the tests within that suite will be executed, while others will be skipped.
+
+**Example:**
+
+```ts
+test.describe.only('group of tests', () => {
+  test('test 1', async ({ page }) => {
+    // test 1 code here
+  });
+
+  test('test 2', async ({ page }) => {
+    // test 2 code here
+  });
+});
+```
+
+> [!IMPORTANT]
+> After debugging, make sure to remove the `.only` suffix to ensure all tests run again during normal execution.
+
+#### 3. Pausing Test Execution
+
+Additionally, you can pause execution of a test by using the `page.pause()` method. This pauses the script execution and allows you to manually inspect the page in the browser.
+
+**Example:**
+
+```ts
+const { test, expect } = require('@playwright/test');
+
+test('example test', async ({ page }) => {
+  await page.goto('https://example.com');
+
+  // Pausing the page to inspect manually
+  await page.pause();
+
+  // Further actions will resume after unpausing
+  const title = await page.title();
+  expect(title).toBe('Example Domain');
+});
+```
+
+> [!IMPORTANT]
+> After debugging, make sure to remove the `page.pause()` call to restore normal test execution.
+
 ## Managing Screenshots
 
 If you are running a test that takes a screenshot, you must first generate the reference screenshot from your reference branch. This is known as generating a "ground truth screenshot". All other screenshots will be compared to this ground truth.