Add blur simulation and implicit focus tracking tests - #164
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Reproduces https://vaadin.com/forum/t/missing-blur-event-simulation-api-in-browserless-test/179736 Business logic is often attached to blur listeners, but there is no public tester API to trigger blur, and Focusable.blur() is a no-op without a browser. Beyond an explicit API, focus and blur should happen implicitly like with a real user: interacting with a component through a tester should focus it and blur the previously focused one. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
FocusTracker keeps per-UI bookkeeping of the focused component and fires focus/blur DOM events through ElementListenerMap, so listeners see events as if they came from the client. Focus moves implicitly like with a real user: setting a value through a tester focuses the field, and interacting with any other component (another setValue, a click, ...) blurs the previously focused one before the new interaction is handled. Interacting again with the already focused component is a no-op. ComponentTester additionally exposes explicit focus() and blur() methods. Fixes the case from https://vaadin.com/forum/t/missing-blur-event-simulation-api-in-browserless-test/179736 Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
knoobie
reviewed
Aug 27, 2026
Focusable.focus()/blur() only schedule a client-side JavaScript call, so they used to be no-ops in browserless tests. FocusTracker now consumes the pending JavaScript queue like a browser would: it materializes beforeClientResponse executions, picks up this.focus()/ this.blur() invocations and fires the corresponding focus/blur DOM events back, updating the focus bookkeeping. The queue is processed at the end of each simulated user interaction (click, setValue, explicit focus/blur) and on server round-trips, so the typical case of a click listener opening a dialog and focusing a field in it works implicitly. ComponentTester also gets isFocused() for asserting the currently focused component. Addresses review feedback in #164 Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Calling focus() directly in test code was contrived; focusing the next field from a value change listener is the realistic application logic this simulates. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
knoobie
reviewed
Aug 27, 2026
Flow's Focusable.focus()/blur() set _nextFocusIsFromClient/ _nextBlurIsFromClient markers in the generated JavaScript, and the FocusEvent/BlurEvent @eventdata constructors use them to override fromClient. Mirror that: server-initiated focus/blur simulation now includes the marker in the DOM event data, so isFromClient() returns false, matching real browser behavior. The blur fired on the previously focused component stays fromClient=true, as it is a plain browser reaction. Also adds a test proving that focus(FocusOption...), which generates this.focus($0) instead of this.focus(), is detected as well. Addresses review feedback from knoobie in #164. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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in Vaadin Flow | Hilla | Kits ongoing work
github-project-automation
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moved this to 🔎Iteration reviews
in Vaadin Flow | Hilla | Kits ongoing work
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Fixes #163 (missing blur simulation, reported in this forum thread (https://vaadin.com/forum/t/missing-blur-event-simulation-api-in-browserless-test/179736)): blur listeners often carry business logic, but there was no tester API to trigger them, and Focusable.focus()/blur() are no-ops without a browser.
The new FocusTracker keeps per-UI bookkeeping of the focused component and makes focus behave like with a real user — no manual blur calls needed:
Known coupling: server-side call detection matches the JS generated by Focusable. If that changes in Flow, the serverSideFocus* tests in BlurSimulationTest fail immediately and a comment at the match site points to both ends.
BlurSimulationTest covers the scenarios above; full suite passes (1241 tests).