feat(breaking): do not throw because event handler was not found (#691)

* do not throw when event handler was not found

* remove unnecessary hasDescendandHandler

Co-authored-by: Pontus Lundin <pontus.lundin@klarna.com>
Co-authored-by: Michał Pierzchała <thymikee@gmail.com>

Author: 3 people

src/__tests__/fireEvent.test.js

@@ -62,14 +62,14 @@ describe('fireEvent', () => {
     expect(onPressMock).toHaveBeenCalled();
   });
 
-  test('should throw an Error when event handler was not found', () => {
+  test('should not fire if the press handler is not passed to children', () => {
+    const onPressMock = jest.fn();
     const { getByText } = render(
-      <WithoutEventComponent onPress={() => 'this is not passed to children'} />
-    );
-
-    expect(() => fireEvent(getByText('Without event'), 'press')).toThrow(
-      'No handler function found for event: "press"'
+      // TODO: this functionality is buggy, i.e. it will fail if we wrap this component with a View.
+      <WithoutEventComponent onPress={onPressMock} />
     );
+    fireEvent(getByText('Without event'), 'press');
+    expect(onPressMock).not.toHaveBeenCalled();
   });
 
   test('should invoke event with custom name', () => {

src/fireEvent.js

@@ -1,6 +1,5 @@
 // @flow
 import act from './act';
-import { ErrorWithStack } from './helpers/errors';
 
 const isHostElement = (element?: ReactTestInstance) => {
   return typeof element?.type === 'string';
@@ -53,8 +52,7 @@ const findEventHandler = (
   element: ReactTestInstance,
   eventName: string,
   callsite?: any,
-  nearestTouchResponder?: ReactTestInstance,
-  hasDescendandHandler?: boolean
+  nearestTouchResponder?: ReactTestInstance
 ) => {
   const touchResponder = isTouchResponder(element)
     ? element
@@ -63,26 +61,11 @@ const findEventHandler = (
   const handler = getEventHandler(element, eventName);
   if (handler && isEventEnabled(element, touchResponder)) return handler;
 
-  // Do not bubble event to the root element
-  const hasHandler = handler != null || hasDescendandHandler;
   if (element.parent === null || element.parent.parent === null) {
-    if (hasHandler) {
-      return null;
-    } else {
-      throw new ErrorWithStack(
-        `No handler function found for event: "${eventName}"`,
-        callsite || invokeEvent
-      );
-    }
+    return null;
   }
 
-  return findEventHandler(
-    element.parent,
-    eventName,
-    callsite,
-    touchResponder,
-    hasHandler
-  );
+  return findEventHandler(element.parent, eventName, callsite, touchResponder);
 };
 
 const getEventHandler = (element: ReactTestInstance, eventName: string) => {