Add toTree() method to stack and fiber TestRenderer (#8931)

* Add toTree() method to stack and fiber TestRenderer

* Address PR feedback

* Refactor TestRenderer to use correct root

* Rebase off master and fix root node references

* Add flow types

* Add test for null rendering components

* Remove last remaining lint error

* Add missing test

scripts/fiber/tests-passing.txt

@@ -1686,6 +1686,9 @@ src/renderers/testing/__tests__/ReactTestRenderer-test.js
 * supports updates when using refs
 * supports error boundaries
 * can update text nodes
+* toTree() renders simple components returning host components
+* toTree() handles null rendering components
+* toTree() renders complicated trees of composites and hosts
 * can update text nodes when rendered as root
 * can render and update root fragments
 

src/renderers/shared/stack/reconciler/ReactCompositeComponent.js

@@ -702,7 +702,7 @@ var ReactCompositeComponent = {
     } else {
       if (__DEV__) {
         const componentName = this.getName();
-        
+
         if (!warningAboutMissingGetChildContext[componentName]) {
           warningAboutMissingGetChildContext[componentName] = true;
           warning(

src/renderers/testing/ReactTestRendererFiber.js

@@ -16,8 +16,19 @@
 var ReactFiberReconciler = require('ReactFiberReconciler');
 var ReactGenericBatching = require('ReactGenericBatching');
 var emptyObject = require('emptyObject');
+var ReactTypeOfWork = require('ReactTypeOfWork');
+var invariant = require('invariant');
+var {
+  FunctionalComponent,
+  ClassComponent,
+  HostComponent,
+  HostText,
+  HostRoot,
+} = ReactTypeOfWork;
 
 import type { TestRendererOptions } from 'ReactTestMount';
+import type { Fiber } from 'ReactFiber';
+import type { FiberRoot } from 'ReactFiberRoot';
 
 type ReactTestRendererJSON = {|
   type : string,
@@ -237,6 +248,58 @@ function toJSON(inst : Instance | TextInstance) : ReactTestRendererNode {
   }
 }
 
+function nodeAndSiblingsArray(nodeWithSibling: ?Fiber) {
+  var array = [];
+  var node = nodeWithSibling;
+  while (node != null) {
+    array.push(node);
+    node = node.sibling;
+  }
+  return array;
+}
+
+function toTree(node: ?Fiber) {
+  if (node == null) {
+    return null;
+  }
+  switch (node.tag) {
+    case HostRoot: // 3
+      return toTree(node.child);
+    case ClassComponent:
+      return {
+        nodeType: 'component',
+        type: node.type,
+        props: { ...node.memoizedProps },
+        instance: node.stateNode,
+        rendered: toTree(node.child),
+      };
+    case FunctionalComponent: // 1
+      return {
+        nodeType: 'component',
+        type: node.type,
+        props: { ...node.memoizedProps },
+        instance: null,
+        rendered: toTree(node.child),
+      };
+    case HostComponent: // 5
+      return {
+        nodeType: 'host',
+        type: node.type,
+        props: { ...node.memoizedProps },
+        instance: null, // TODO: use createNodeMock here somehow?
+        rendered: nodeAndSiblingsArray(node.child).map(toTree),
+      };
+    case HostText: // 6
+      return node.stateNode.text;
+    default:
+      invariant(
+        false,
+        'toTree() does not yet know how to handle nodes with tag=%s',
+        node.tag
+      );
+  }
+}
+
 var ReactTestFiberRenderer = {
   create(element : ReactElement<any>, options : TestRendererOptions) {
     var createNodeMock = defaultTestOptions.createNodeMock;
@@ -248,12 +311,13 @@ var ReactTestFiberRenderer = {
       createNodeMock,
       tag: 'CONTAINER',
     };
-    var root = TestRenderer.createContainer(container);
+    var root: ?FiberRoot = TestRenderer.createContainer(container);
+    invariant(root != null, 'something went wrong');
     TestRenderer.updateContainer(element, root, null, null);
 
     return {
       toJSON() {
-        if (root == null || container == null) {
+        if (root == null || root.current == null || container == null) {
           return null;
         }
         if (container.children.length === 0) {
@@ -264,14 +328,20 @@ var ReactTestFiberRenderer = {
         }
         return container.children.map(toJSON);
       },
+      toTree() {
+        if (root == null || root.current == null) {
+          return null;
+        }
+        return toTree(root.current);
+      },
       update(newElement : ReactElement<any>) {
-        if (root == null) {
+        if (root == null || root.current == null) {
           return;
         }
         TestRenderer.updateContainer(newElement, root, null, null);
       },
       unmount() {
-        if (root == null) {
+        if (root == null || root.current == null) {
           return;
         }
         TestRenderer.updateContainer(null, root, null);
@@ -279,7 +349,7 @@ var ReactTestFiberRenderer = {
         root = null;
       },
       getInstance() {
-        if (root == null) {
+        if (root == null || root.current == null) {
           return null;
         }
         return TestRenderer.getPublicRootInstance(root);

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

@@ -14,8 +14,32 @@
 var React = require('React');
 var ReactTestRenderer = require('ReactTestRenderer');
 var ReactDOMFeatureFlags = require('ReactDOMFeatureFlags');
+var prettyFormat = require('pretty-format');
 var ReactFeatureFlags;
 
+// Kind of hacky, but we nullify all the instances to test the tree structure
+// with jasmine's deep equality function, and test the instances separate. We
+// also delete children props because testing them is more annoying and not
+// really important to verify.
+function cleanNode(node) {
+  if (!node) {
+    return;
+  }
+  if (node && node.instance) {
+    node.instance = null;
+  }
+  if (node && node.props && node.props.children) {
+    // eslint-disable-next-line no-unused-vars
+    var { children, ...props } = node.props;
+    node.props = props;
+  }
+  if (Array.isArray(node.rendered)) {
+    node.rendered.forEach(cleanNode);
+  } else if (typeof node.rendered === 'object') {
+    cleanNode(node.rendered);
+  }
+}
+
 describe('ReactTestRenderer', () => {
   beforeEach(() => {
     ReactFeatureFlags = require('ReactFeatureFlags');
@@ -517,6 +541,152 @@ describe('ReactTestRenderer', () => {
     });
   });
 
+  it('toTree() renders simple components returning host components', () => {
+
+    var Qoo = () => (
+      <span className="Qoo">Hello World!</span>
+    );
+
+    var renderer = ReactTestRenderer.create(<Qoo />);
+    var tree = renderer.toTree();
+
+    cleanNode(tree);
+
+    expect(prettyFormat(tree)).toEqual(prettyFormat({
+      nodeType: 'component',
+      type: Qoo,
+      props: {},
+      instance: null,
+      rendered: {
+        nodeType: 'host',
+        type: 'span',
+        props: { className: 'Qoo' },
+        instance: null,
+        rendered: ['Hello World!'],
+      },
+    }));
+
+  });
+
+  it('toTree() handles null rendering components', () => {
+    class Foo extends React.Component {
+      render() {
+        return null;
+      }
+    }
+
+    var renderer = ReactTestRenderer.create(<Foo />);
+    var tree = renderer.toTree();
+
+    expect(tree.instance).toBeInstanceOf(Foo);
+
+    cleanNode(tree);
+
+    expect(tree).toEqual({
+      type: Foo,
+      nodeType: 'component',
+      props: { },
+      instance: null,
+      rendered: null,
+    });
+
+  });
+
+  it('toTree() renders complicated trees of composites and hosts', () => {
+    // SFC returning host. no children props.
+    var Qoo = () => (
+      <span className="Qoo">Hello World!</span>
+    );
+
+    // SFC returning host. passes through children.
+    var Foo = ({ className, children }) => (
+      <div className={'Foo ' + className}>
+        <span className="Foo2">Literal</span>
+        {children}
+      </div>
+    );
+
+    // class composite returning composite. passes through children.
+    class Bar extends React.Component {
+      render() {
+        const { special, children } = this.props;
+        return (
+          <Foo className={special ? 'special' : 'normal'}>
+            {children}
+          </Foo>
+        );
+      }
+    }
+
+    // class composite return composite. no children props.
+    class Bam extends React.Component {
+      render() {
+        return (
+          <Bar special={true}>
+            <Qoo />
+          </Bar>
+        );
+      }
+    }
+
+    var renderer = ReactTestRenderer.create(<Bam />);
+    var tree = renderer.toTree();
+
+    // we test for the presence of instances before nulling them out
+    expect(tree.instance).toBeInstanceOf(Bam);
+    expect(tree.rendered.instance).toBeInstanceOf(Bar);
+
+    cleanNode(tree);
+
+    expect(prettyFormat(tree)).toEqual(prettyFormat({
+      type: Bam,
+      nodeType: 'component',
+      props: {},
+      instance: null,
+      rendered: {
+        type: Bar,
+        nodeType: 'component',
+        props: { special: true },
+        instance: null,
+        rendered: {
+          type: Foo,
+          nodeType: 'component',
+          props: { className: 'special' },
+          instance: null,
+          rendered: {
+            type: 'div',
+            nodeType: 'host',
+            props: { className: 'Foo special' },
+            instance: null,
+            rendered: [
+              {
+                type: 'span',
+                nodeType: 'host',
+                props: { className: 'Foo2' },
+                instance: null,
+                rendered: ['Literal'],
+              },
+              {
+                type: Qoo,
+                nodeType: 'component',
+                props: {},
+                instance: null,
+                rendered: {
+                  type: 'span',
+                  nodeType: 'host',
+                  props: { className: 'Qoo' },
+                  instance: null,
+                  rendered: ['Hello World!'],
+                },
+              },
+            ],
+          },
+        },
+      },
+    }));
+
+  });
+
   if (ReactDOMFeatureFlags.useFiber) {
     it('can update text nodes when rendered as root', () => {
       var renderer = ReactTestRenderer.create(['Hello', 'world']);

src/renderers/testing/stack/ReactTestMount.js

@@ -138,6 +138,9 @@ ReactTestInstance.prototype.unmount = function(nextElement) {
   });
   this._component = null;
 };
+ReactTestInstance.prototype.toTree = function() {
+  return toTree(this._component._renderedComponent);
+};
 ReactTestInstance.prototype.toJSON = function() {
   var inst = getHostComponentFromComposite(this._component);
   if (inst === null) {
@@ -146,6 +149,39 @@ ReactTestInstance.prototype.toJSON = function() {
   return inst.toJSON();
 };
 
+function toTree(component) {
+  var element = component._currentElement;
+  if (!React.isValidElement(element)) {
+    return element;
+  }
+  if (!component._renderedComponent) {
+    var rendered = [];
+    for (var key in component._renderedChildren) {
+      var inst = component._renderedChildren[key];
+      var json = toTree(inst);
+      if (json !== undefined) {
+        rendered.push(json);
+      }
+    }
+
+    return {
+      nodeType: 'host',
+      type: element.type,
+      props: { ...element.props },
+      instance: component._nodeMock,
+      rendered: rendered,
+    };
+  } else {
+    return {
+      nodeType: 'component',
+      type: element.type,
+      props: { ...element.props },
+      instance: component._instance,
+      rendered: toTree(component._renderedComponent),
+    };
+  }
+}
+
 /**
  * As soon as `ReactMount` is refactored to not rely on the DOM, we can share
  * code between the two. For now, we'll hard code the ID logic.