Stack test renderer: cache nodeMock to not call on unmount

Author: iamdustan

src/renderers/shared/shared/__tests__/refs-test.js

@@ -290,27 +290,6 @@ describe('ref swapping', () => {
     expect(a.refs[1].nodeName).toBe('DIV');
   });
 
-  it('supports updates with unmounts correctly when using refs', () => {
-    const ReactDOM = require('ReactDOM');
-    const container = document.createElement('div');
-    const log = [];
-    const ref = element => {
-      const result = element == null ? null : element.nodeName.toLowerCase();
-      log.push(result);
-      return result;
-    };
-    class Foo extends React.Component {
-      render() {
-        return this.props.useDiv
-          ? <div ref={ref}/>
-          : <span ref={ref} />;
-      }
-    }
-    ReactDOM.render(<Foo useDiv={true} />, container);
-    ReactDOM.render(<Foo useDiv={false} />, container);
-    expect(log).toEqual(['div', null, 'span']);
-  });
-
 });
 
 describe('string refs between fiber and stack', () => {

src/renderers/testing/__tests__/ReactTestRenderer-test.js

@@ -392,8 +392,7 @@ describe('ReactTestRenderer', () => {
       {createNodeMock}
     );
     inst.update(<Foo useDiv={false} />);
-    // It's called with 'div' twice (mounting and unmounting)
-    expect(log).toEqual(['div', 'div', 'span']);
+    expect(log).toEqual(['div', 'span']);
   });
 
   it('supports error boundaries', () => {

src/renderers/testing/stack/ReactTestRendererStack.js

@@ -50,17 +50,21 @@ function getRenderedHostOrTextFromComponent(component) {
   return component;
 }
 
+var UNSET = {};
+
 class ReactTestComponent {
   _currentElement: ReactElement;
   _renderedChildren: null | Object;
   _topLevelWrapper: null | ReactInstance;
   _hostContainerInfo: null | Object;
+  _nodeMock: Object;
 
   constructor(element: ReactElement) {
     this._currentElement = element;
     this._renderedChildren = null;
     this._topLevelWrapper = null;
     this._hostContainerInfo = null;
+    this._nodeMock = UNSET;
   }
 
   mountComponent(
@@ -93,7 +97,10 @@ class ReactTestComponent {
       'hostContainerInfo should be populated before ' +
       'getPublicInstance is called.'
     );
-    return hostContainerInfo.createNodeMock(element);
+    if (this._nodeMock === UNSET) {
+      this._nodeMock = hostContainerInfo.createNodeMock(element);
+    }
+    return this._nodeMock;
   }
 
   toJSON(): ReactTestRendererJSON {