[Fiber] Add unit tests for ReactDOMFiber (facebook#8016)

src/renderers/dom/fiber/__tests__/ReactDOMFiber-test.js

@@ -0,0 +1,68 @@
+/**
+ * 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';
+
+var React = require('React');
+var ReactDOM = require('ReactDOM');
+var ReactDOMFeatureFlags = require('ReactDOMFeatureFlags');
+
+describe('ReactDOMFiber', () => {
+  var container;
+
+  beforeEach(() => {
+    container = document.createElement('div');
+  });
+
+  it('should render strings as children', () => {
+    const Box = ({value}) => <div>{value}</div>;
+
+    ReactDOM.render(
+      <Box value="foo" />,
+      container
+    );
+    expect(container.textContent).toEqual('foo');
+  });
+
+  it('should render numbers as children', () => {
+    const Box = ({value}) => <div>{value}</div>;
+
+    ReactDOM.render(
+      <Box value={10} />,
+      container
+    );
+
+    expect(container.textContent).toEqual('10');
+  });
+
+  if (ReactDOMFeatureFlags.useFiber) {
+    it('should render a component returning strings directly from render', () => {
+      const Text = ({value}) => value;
+
+      ReactDOM.render(
+        <Text value="foo" />,
+        container
+      );
+      expect(container.textContent).toEqual('foo');
+    });
+
+    it('should render a component returning numbers directly from render', () => {
+      const Text = ({value}) => value;
+
+      ReactDOM.render(
+        <Text value={10} />,
+        container
+      );
+
+      expect(container.textContent).toEqual('10');
+    });
+  }
+});