Check existence of native methods before calling them in NativeEventE…

…mitter

Summary:
Check the existence of `addListener` and `removeListeners` in the native module passed to `NativeEventEmitter` to determine if it can be used.

Changelog: [General][Changed] Show warning when native module without `addListener` or `removeListeners` is passed to `NativeEventEmitter`

Reviewed By: yungsters

Differential Revision: D27851425

fbshipit-source-id: c0ad3ba65a9239f5bf84548dab36e8dfbc51058a

Libraries/EventEmitter/NativeEventEmitter.js

@@ -46,7 +46,26 @@ export default class NativeEventEmitter<TEventToArgsMap: {...}>
         '`new NativeEventEmitter()` requires a non-null argument.',
       );
     }
-    this._nativeModule = nativeModule;
+
+    const hasAddListener =
+      !!nativeModule && typeof nativeModule.addListener === 'function';
+    const hasRemoveListeners =
+      !!nativeModule && typeof nativeModule.removeListeners === 'function';
+
+    if (nativeModule && hasAddListener && hasRemoveListeners) {
+      this._nativeModule = nativeModule;
+    } else {
+      if (!hasAddListener) {
+        console.warn(
+          '`new NativeEventEmitter()` was called with a non-null argument without the required `addListener` method.',
+        );
+      }
+      if (!hasRemoveListeners) {
+        console.warn(
+          '`new NativeEventEmitter()` was called with a non-null argument without the required `removeListeners` method.',
+        );
+      }
+    }
   }
 
   addListener<TEvent: $Keys<TEventToArgsMap>>(