docs(test-parameterize): improve forEach example (#31331)

docs/src/test-parameterize-js.md

@@ -9,13 +9,61 @@ You can either parameterize tests on a test level or on a project level.
 ## Parameterized Tests
 
 ```js title="example.spec.ts"
-const people = ['Alice', 'Bob'];
-for (const name of people) {
-  test(`testing with ${name}`, async () => {
-    // ...
-  });
+[
+  { name: 'Alice', expected: 'Hello, Alice!' },
+  { name: 'Bob', expected: 'Hello, Bob!' },
+  { name: 'Charlie', expected: 'Hello, Charlie!' },
+].forEach(({ name, expected }) => {
   // You can also do it with test.describe() or with multiple tests as long the test name is unique.
-}
+  test(`testing with ${name}`, async ({ page }) => {
+    await page.goto(`https://example.com/greet?name=${name}`);
+    await expect(page.getByRole('heading')).toHaveText(expected);
+  });
+});
+```
+
+### Before and after hooks
+
+Most of the time you should put `beforeEach`, `beforeAll`, `afterEach` and `afterAll` hooks outside of `forEach`, so that hooks are executed just once:
+
+```js title="example.spec.ts"
+test.beforeEach(async ({ page }) => {
+  // ...
+});
+
+test.afterEach(async ({ page }) => {
+  // ...
+});
+
+[
+  { name: 'Alice', expected: 'Hello, Alice!' },
+  { name: 'Bob', expected: 'Hello, Bob!' },
+  { name: 'Charlie', expected: 'Hello, Charlie!' },
+].forEach(({ name, expected }) => {
+  test(`testing with ${name}`, async ({ page }) => {
+    await page.goto(`https://example.com/greet?name=${name}`);
+    await expect(page.getByRole('heading')).toHaveText(expected);
+  });
+});
+```
+
+If you want to have hooks for each test, you can put them inside a `describe()` - so they are executed for each iteration / each invidual test:
+
+```js title="example.spec.ts"
+[
+  { name: 'Alice', expected: 'Hello, Alice!' },
+  { name: 'Bob', expected: 'Hello, Bob!' },
+  { name: 'Charlie', expected: 'Hello, Charlie!' },
+].forEach(({ name, expected }) => {
+  test.describe(() => {
+    test.beforeEach(async ({ page }) => {
+      await page.goto(`https://example.com/greet?name=${name}`);
+    });
+    test(`testing with ${expected}`, async ({ page }) => {
+      await expect(page.getByRole('heading')).toHaveText(expected);
+    });
+  });
+});
 ```
 
 ## Parameterized Projects