[Tests] add more render tests

packages/enzyme-test-suite/test/staticRender-spec.jsx

@@ -21,15 +21,25 @@ describeWithDOM('render', () => {
 
       const context = { name: 'foo' };
       const wrapper = render(<SimpleComponent />, { context });
+
+      const rootEls = wrapper.children();
+      expect(rootEls).to.have.lengthOf(1);
+
+      expect(rootEls.is('div')).to.equal(true);
+      expect(rootEls.text()).to.equal('foo');
       expect(wrapper.text()).to.equal('foo');
+
+      expect(String(wrapper)).to.equal('<div>foo</div>');
+      expect(String(rootEls)).to.equal('<div>foo</div>');
     });
+
     it('can pass context to the child of mounted component', () => {
       const SimpleComponent = createClass({
         contextTypes: {
           name: PropTypes.string,
         },
         render() {
-          return <div>{this.context.name}</div>;
+          return <span>{this.context.name}</span>;
         },
       });
       const ComplexComponent = createClass({
@@ -43,9 +53,23 @@ describeWithDOM('render', () => {
       };
       const context = { name: 'foo' };
       const wrapper = render(<ComplexComponent />, { context, childContextTypes });
-      expect(wrapper.children()).to.have.length(1);
-      expect(wrapper.children().first().text()).to.equal('foo');
+
+      const rootEls = wrapper.children();
+      expect(rootEls).to.have.length(1);
+
+      expect(rootEls.is('div')).to.equal(true);
+
+      const children = rootEls.children();
+      expect(children).to.have.length(1);
+      expect(children.is('span')).to.equal(true);
+
+      expect(children.first().text()).to.equal('foo');
+
+      expect(String(wrapper)).to.equal('<div><span>foo</span></div>');
+      expect(String(rootEls)).to.equal('<div><span>foo</span></div>');
+      expect(String(children)).to.equal('<span>foo</span>');
     });
+
     it('should not throw if context is passed in but contextTypes is missing', () => {
       const SimpleComponent = createClass({
         render() {