Skip to content

docs: document hydration completion check for e2e tests #68082

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Closed
splincode wants to merge 1 commit into from
+11 −0
Closed

docs: document hydration completion check for e2e tests #68082

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
11 changes: 11 additions & 0 deletions adev/src/content/guide/hydration.md
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -61,6 +61,17 @@ While running an application in dev mode, you can confirm hydration is enabled b

You can also use [Angular DevTools browser extension](tools/devtools) to see hydration status of components on a page. Angular DevTools also allows to enable an overlay to indicate which parts of the page were hydrated. If there is a hydration mismatch error - DevTools would also highlight a component that caused the error.

### Verify hydration in E2E tests

During hydration, Angular annotates component host elements with an `ngh` attribute that contains hydration metadata. After hydration finishes, Angular removes these attributes.

In end-to-end tests, you can wait for hydration to complete by asserting that there are no `[ngh]` attributes left in the DOM. For example, in Playwright:

```typescript
// Ensure hydration is finished
await expect(app.locator('[ngh]')).toHaveCount(0);
```

## Capturing and replaying events

When an application is rendered on the server, it is visible in a browser as soon as produced HTML loads. Users may assume that they can interact with the page, but event listeners are not attached until hydration completes. Starting from v18, you can enable the Event Replay feature that allows to capture all events that happen before hydration and replay those events once hydration has completed. You can enable it using the `withEventReplay()` function, for example:
Expand Down
Loading