Add test for deprecation warnings

Author: Brandon Dail

src/isomorphic/__tests__/React-test.js

@@ -0,0 +1,42 @@
+/**
+ * Copyright 2013-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ *
+ * @emails react-core
+ */
+
+'use strict';
+
+describe('React', () => {
+
+  var React;
+
+  beforeEach(() => {
+    React = require('React');
+  });
+
+  it('should log a deprecation warning once when using React.__spread', () => {
+    spyOn(console, 'error');
+    React.__spread({});
+    React.__spread({});
+    expect(console.error.calls.count()).toBe(1);
+    expect(console.error.calls.argsFor(0)[0]).toContain(
+      'React.__spread is deprecated and should not be used'
+    );
+  });
+
+  it('should log a deprecation warning once when using React.createMixin', () => {
+    spyOn(console, 'error');
+    React.createMixin();
+    React.createMixin();
+    expect(console.error.calls.count()).toBe(1);
+    expect(console.error.calls.argsFor(0)[0]).toContain(
+      'React.createMixin is deprecated and should not be used'
+    );
+  });
+
+});