Add smoke tests for styles (including SSR) (#10308)

* Add style to ReactDOM smoke test

* Add production smoke test for ReactDOMServer

Author: gaearon

src/renderers/dom/__tests__/ReactDOMProduction-test.js

@@ -15,6 +15,7 @@ describe('ReactDOMProduction', () => {
 
   var React;
   var ReactDOM;
+  var ReactDOMServer;
   var oldProcess;
 
   beforeEach(() => {
@@ -31,6 +32,7 @@ describe('ReactDOMProduction', () => {
     jest.resetModules();
     React = require('react');
     ReactDOM = require('react-dom');
+    ReactDOMServer = require('react-dom/server');
   });
 
   afterEach(() => {
@@ -64,7 +66,7 @@ describe('ReactDOMProduction', () => {
 
     var container = document.createElement('div');
     var inst = ReactDOM.render(
-      <div className="blue">
+      <div className="blue" style={{fontFamily: 'Helvetica'}}>
         <Component key={1}>A</Component>
         <Component key={2}>B</Component>
         <Component key={3}>C</Component>
@@ -74,10 +76,11 @@ describe('ReactDOMProduction', () => {
 
     expect(container.firstChild).toBe(inst);
     expect(inst.className).toBe('blue');
+    expect(inst.style.fontFamily).toBe('Helvetica');
     expect(inst.textContent).toBe('ABC');
 
     ReactDOM.render(
-      <div className="red">
+      <div className="red" style={{fontFamily: 'Comic Sans MS'}}>
         <Component key={2}>B</Component>
         <Component key={1}>A</Component>
         <Component key={3}>C</Component>
@@ -86,13 +89,38 @@ describe('ReactDOMProduction', () => {
     );
 
     expect(inst.className).toBe('red');
+    expect(inst.style.fontFamily).toBe('Comic Sans MS');
     expect(inst.textContent).toBe('BAC');
 
     ReactDOM.unmountComponentAtNode(container);
 
     expect(container.childNodes.length).toBe(0);
   });
 
+  it('should handle a simple flow (ssr)', () => {
+    class Component extends React.Component {
+      render() {
+        return <span>{this.props.children}</span>;
+      }
+    }
+
+    var container = document.createElement('div');
+    var markup = ReactDOMServer.renderToString(
+      <div className="blue" style={{fontFamily: 'Helvetica'}}>
+        <Component key={1}>A</Component>
+        <Component key={2}>B</Component>
+        <Component key={3}>C</Component>
+      </div>,
+      container,
+    );
+    container.innerHTML = markup;
+    var inst = container.firstChild;
+
+    expect(inst.className).toBe('blue');
+    expect(inst.style.fontFamily).toBe('Helvetica');
+    expect(inst.textContent).toBe('ABC');
+  });
+
   it('should call lifecycle methods', () => {
     var log = [];
     class Component extends React.Component {