Add unregister feature to ReactNativePropRegistry

src/renderers/native/ReactNativePropRegistry.js

@@ -32,11 +32,24 @@ class ReactNativePropRegistry {
 
     var object = objects[id];
     if (!object) {
-      console.warn('Invalid style with id `' + id + '`. Skipping ...');
+      if (id > 1 && id <= uniqueID) {
+        // We cannot directly test for unregistered objects because keeping a permanent registry of them
+        // would leak memory, however we do know that ids above 1 and below uniqueID were once registered
+        console.warn(
+          'Style with id `' + id + '` has been unregistered. Skipping ...',
+        );
+      } else {
+        console.warn('Invalid style with id `' + id + '`. Skipping ...');
+      }
       return emptyObject;
     }
     return object;
   }
+
+  static unregister(id: number): void {
+    // delete is used instead of setting to null so we don't slowly leak memory by keeping keys
+    delete objects[id];
+  }
 }
 
 module.exports = ReactNativePropRegistry;

src/renderers/native/__tests__/ReactNativePropRegistry-test.js

@@ -0,0 +1,80 @@
+/**
+ * Copyright (c) 2013-present, Facebook, Inc.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ */
+'use strict';
+
+var ReactNativePropRegistry = require('ReactNativePropRegistry');
+
+var register = ReactNativePropRegistry.register;
+var getByID = ReactNativePropRegistry.getByID;
+var unregister = ReactNativePropRegistry.unregister;
+var devOnlyIt = __DEV__ ? it : it.skip;
+
+describe('ReactNativePropRegistry', () => {
+	describe('register', () => {
+		it('should return an integer', () => {
+			expect(typeof register({})).toBe('number');
+		});
+
+		it('should not return the same integer across different calls', () => {
+			var a = register({});
+			var b = register({});
+
+			expect(b).not.toBe(a);
+		});
+
+		devOnlyIt('should freeze the input object in __DEV__ mode', () => {
+			var object = {a: 1};
+			register(object);
+			expect(() => {
+				object.a = 2;
+			}).toThrowErrorMatchingSnapshot();
+		});
+	});
+
+	describe('getByID', () => {
+		it('should return an empty object when passed undefined, null, false, or 0', () => {
+			expect(getByID(undefined)).toEqual({});
+			expect(getByID(null)).toEqual({});
+			expect(getByID(false)).toEqual({});
+			expect(getByID(0)).toEqual({});
+		});
+
+		it('should warn and return an empty object when passed an unknown id', () => {
+			var spy = spyOn(console, 'warn');
+			expect(getByID(999999999999999)).toEqual({});
+			expect(spy).toHaveBeenCalledWith('Invalid style with id `999999999999999`. Skipping ...');
+		});
+
+		it('should warn and return an empty object when passed an id for an unregistered object', () => {
+			var spy = spyOn(console, 'warn');
+			var object = {a: 1};
+			var id = register(object);
+			unregister(id);
+			expect(getByID(id)).toEqual({});
+			expect(spy).toHaveBeenCalledWith('Style with id `' + id + '` has been unregistered. Skipping ...');
+		});
+
+		it('should return an object registered with register', () => {
+			var object = {a: 1};
+			var id = register(object);
+			expect(getByID(id)).toBe(object);
+		});
+	});
+
+	describe('unregister', () => {
+		it('should unregister objects so getByID does not return them', () => {
+			spyOn(console, 'warn');
+			var object = {a: 1};
+			var id = register(object);
+			unregister(id);
+			var result = getByID(id);
+			expect(result).not.toBe(object);
+			expect(result).toEqual({});
+		});
+	});
+});

src/renderers/native/__tests__/__snapshots__/ReactNativePropRegistry-test.js.snap

@@ -0,0 +1,3 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`ReactNativePropRegistry register should freeze the input object in __DEV__ mode 1`] = `"Cannot assign to read only property 'a' of object '#<Object>'"`;