[fix] AppState.removeEventListener deprecation

Fix #2215
Fix #2166

packages/react-native-web/src/exports/AppState/__tests__/index-test.js

@@ -10,23 +10,10 @@ describe('apis/AppState', () => {
       expect(() => AppState.addEventListener('foo', handler)).toThrow();
       expect(() => AppState.addEventListener('change', handler).remove()).not.toThrow();
     });
-  });
 
-  describe('removeEventListener', () => {
-    beforeEach(() => {
-      // removeEventListener logs a deprecation warning, ignore
-      jest.spyOn(console, 'error');
-      console.error.mockImplementation(() => {});
-    });
-
-    afterEach(() => {
-      console.error.mockRestore();
-    });
-
-    test('throws if the provided "eventType" is not supported', () => {
-      AppState.addEventListener('change', handler);
-      expect(() => AppState.removeEventListener('foo', handler)).toThrow();
-      expect(() => AppState.removeEventListener('change', handler)).not.toThrow();
+    test('returns remove subscription', () => {
+      const subscription = AppState.addEventListener('change', handler);
+      expect(() => subscription.remove()).not.toThrow();
     });
   });
 });

packages/react-native-web/src/exports/AppState/index.js

@@ -72,6 +72,11 @@ export default class AppState {
 
   static removeEventListener(type: string, handler: Function) {
     if (AppState.isAvailable) {
+      console.error(
+        `AppState.removeListener('${type}', ...): Method has been ` +
+          'deprecated. Please instead use `remove()` on the subscription ' +
+          'returned by `AppState.addEventListener`.'
+      );
       invariant(
         EVENT_TYPES.indexOf(type) !== -1,
         'Trying to remove listener for unknown event: "%s"',