From 32d17280166b0b322479ab15903d16537cf3749c Mon Sep 17 00:00:00 2001
From: Dominic Gannaway <dg@domgan.com>
Date: Wed, 18 Sep 2019 19:43:20 +0100
Subject: [PATCH] address comment

---
 .../src/events/DOMEventResponderSystem.js     | 10 ++++++++
 .../DOMEventResponderSystem-test.internal.js  | 24 +++++++++++++++++++
 2 files changed, 34 insertions(+)

diff --git a/packages/react-dom/src/events/DOMEventResponderSystem.js b/packages/react-dom/src/events/DOMEventResponderSystem.js
index bb4589437d95e..14bd5f5fff734 100644
--- a/packages/react-dom/src/events/DOMEventResponderSystem.js
+++ b/packages/react-dom/src/events/DOMEventResponderSystem.js
@@ -303,6 +303,16 @@ function validateEventValue(eventValue: any): void {
         );
       }
     };
+    eventValue.isDefaultPrevented = () => {
+      if (__DEV__) {
+        showWarning('isDefaultPrevented()');
+      }
+    };
+    eventValue.isPropagationStopped = () => {
+      if (__DEV__) {
+        showWarning('isPropagationStopped()');
+      }
+    };
     // $FlowFixMe: we don't need value, Flow thinks we do
     Object.defineProperty(eventValue, 'nativeEvent', {
       get() {
diff --git a/packages/react-dom/src/events/__tests__/DOMEventResponderSystem-test.internal.js b/packages/react-dom/src/events/__tests__/DOMEventResponderSystem-test.internal.js
index bc09dd8be7650..83f17d0c1723d 100644
--- a/packages/react-dom/src/events/__tests__/DOMEventResponderSystem-test.internal.js
+++ b/packages/react-dom/src/events/__tests__/DOMEventResponderSystem-test.internal.js
@@ -837,6 +837,30 @@ describe('DOMEventResponderSystem', () => {
         </button>
       );
     };
+    expect(() => {
+      handler = event => {
+        event.isDefaultPrevented();
+      };
+      ReactDOM.render(<Test />, container);
+      dispatchClickEvent(buttonRef.current);
+    }).toWarnDev(
+      'Warning: isDefaultPrevented() is not available on event objects created from event responder modules ' +
+        '(React Flare).' +
+        ' Try wrapping in a conditional, i.e. `if (event.type !== "press") { event.isDefaultPrevented() }`',
+      {withoutStack: true},
+    );
+    expect(() => {
+      handler = event => {
+        event.isPropagationStopped();
+      };
+      ReactDOM.render(<Test />, container);
+      dispatchClickEvent(buttonRef.current);
+    }).toWarnDev(
+      'Warning: isPropagationStopped() is not available on event objects created from event responder modules ' +
+        '(React Flare).' +
+        ' Try wrapping in a conditional, i.e. `if (event.type !== "press") { event.isPropagationStopped() }`',
+      {withoutStack: true},
+    );
     expect(() => {
       handler = event => {
         return event.nativeEvent;