Angular Testing Library v17.1.0 introduces a new `on` API for testing component output properties. Previously, developers had to use `componentOutputs` or `componentProperties`, which lacked type safety and required manual creation of fake event emitters with type assertions. The new `on` property is set in the `render` function, accepts a spy or callback, and automatically unsubscribes when the component is destroyed or rerendered. As a result, `componentOutputs` and `componentProperties` are now deprecated and will be removed in the next major version.
