An example of the `subject` pattern for DRYer Jasmine specs

subject-pattern.js.jsx

describe('Button', () => {
  beforeEach(() => {
    this.subject = () => {
      return React.addons.TestUtils.renderIntoDocument(
        <Button {...this.props} />  
      );
    };
  });
  
  describe('with a `text` prop', => {
    beforeEach(() => this.props = { text: 'Click me'});
    
    it('renders the text', () => {
      expect(this.subject()).toHaveText('Click me');
    });
    
    describe('and an `icon` prop', () => {
      beforeEach(() => this.props.icon = 'email');
      
      it('renders the icon', () => {
        expect(this.subject()).toHaveIcon('email');
      });
      
      it('renders the text', () => {
        expect(this.subject()).toHaveText('Click me');
      });
    });
  });
});