Add equals method to ShallowWrapper.

Author: themouette

docs/api/ShallowWrapper/equals.md

@@ -0,0 +1,35 @@
+# `.equals(node) => Boolean`
+
+Returns whether or not the current wrapper root node render tree looks like the one passed in.
+
+
+#### Arguments
+
+1. `node` (`ReactElement`): The node whose presence you are detecting in the current instance's
+render tree.
+
+
+
+#### Returns
+
+`Boolean`: whether or not the current wrapper has a node anywhere in it's render tree that looks
+like the one passed in.
+
+
+
+#### Example
+
+
+```jsx
+const wrapper = shallow(<MyComponent />);
+expect(wrapper.equals(<div className="foo bar" />)).to.equal(true);
+```
+
+
+#### Common Gotchas
+
+- `.equals()` expects a ReactElement, not a selector (like many other methods). Make sure that
+when you are calling it you are calling it with a ReactElement or a JSX expression.
+- Keep in mind that this method determines equality based on the equality of the node's children as
+well.
+

src/ShallowWrapper.js

@@ -205,6 +205,22 @@ export default class ShallowWrapper {
     return findWhereUnwrapped(this, other => nodeEqual(node, other)).length > 0;
   }
 
+  /**
+   * Whether or not a given react element exists in the shallow render tree.
+   *
+   * Example:
+   * ```
+   * const wrapper = shallow(<MyComponent />);
+   * expect(wrapper.contains(<div className="foo bar" />)).to.equal(true);
+   * ```
+   *
+   * @param {ReactElement} node
+   * @returns {Boolean}
+   */
+  equals(node) {
+    return nodeEqual(this.node, node);
+  }
+
   /**
    * Finds every node in the render tree of the current wrapper that matches the provided selector.
    *

src/__tests__/ShallowWrapper-spec.js

@@ -85,6 +85,54 @@ describe('shallow', () => {
 
   });
 
+  describe('.equals(node)', () => {
+
+    it('should allow matches on the root node', () => {
+      const a = <div className="foo" />;
+      const b = <div className="foo" />;
+      const c = <div className="bar" />;
+      expect(shallow(a).equals(b)).to.equal(true);
+      expect(shallow(a).equals(c)).to.equal(false);
+    });
+
+    it('should NOT allow matches on a nested node', () => {
+      const wrapper = shallow(
+        <div>
+          <div className="foo" />
+        </div>
+      );
+      const b = <div className="foo" />;
+      expect(wrapper.equals(b)).to.equal(false);
+    });
+
+    it('should match composite components', () => {
+      class Foo extends React.Component {
+        render() { return <div />; }
+      }
+      const wrapper = shallow(
+        <div>
+          <Foo />
+        </div>
+      );
+      const b = <div><Foo /></div>;
+      expect(wrapper.equals(b)).to.equal(true);
+    });
+
+    it('should not expand `node` content', () => {
+      class Bar extends React.Component {
+        render() { return <div />; }
+      }
+
+      class Foo extends React.Component {
+        render() { return <Bar />; }
+      }
+
+      expect(shallow(<Foo />).equals(<Bar />)).to.equal(true);
+      expect(shallow(<Foo />).equals(<Foo />)).to.equal(false);
+    });
+
+  });
+
   describe('.find(selector)', () => {
 
     it('should be able to match the root DOM element', () => {