Add findAll base query method (facebook#42829)

Summary:
Pull Request resolved: facebook#42829

This is the base query method that we can wrap to use specific matchers like `findByTestID` or `findByRole`

Changelog: [internal]

Reviewed By: noahlemen

Differential Revision: D53359005

fbshipit-source-id: d1ac9c503b05d479567b6ced71d4517d5bc55b0b

packages/react-native-test-renderer/src/renderer/__tests__/render-test.js

@@ -45,4 +45,19 @@ describe('render', () => {
       expect(result.toJSON()).toMatchSnapshot();
     });
   });
+
+  describe('findAll', () => {
+    it('returns all nodes matching the predicate', () => {
+      const result = ReactNativeTestRenderer.render(<TestComponent />);
+      const textNode = result.findAll(node => {
+        return node.props?.text === 'Hello';
+      })[0];
+      expect(textNode).not.toBeUndefined();
+
+      const viewNodes = result.findAll(node => {
+        return node.viewName === 'RCTView';
+      });
+      expect(viewNodes.length).toBe(2);
+    });
+  });
 });

packages/react-native-test-renderer/src/renderer/index.js

@@ -25,11 +25,10 @@ type FiberPartial = {
 };
 
 type ReactNode = {
-  children: $ReadOnlyArray<ReactNode>,
+  children: ?Array<ReactNode>,
   props: {text?: string | null, ...},
   viewName: string,
   instanceHandle: FiberPartial,
-  ...
 };
 
 type RenderedNodeJSON = {
@@ -41,12 +40,14 @@ type RenderedNodeJSON = {
 type RenderedJSON = RenderedNodeJSON | string;
 
 type RenderResult = {
-  toJSON: () => $ReadOnlyArray<RenderedJSON> | RenderedJSON | null,
+  toJSON: () => Array<RenderedJSON> | RenderedJSON | null,
+  findAll: (predicate: (ReactNode) => boolean) => Array<ReactNode>,
 };
 
 function buildRenderResult(rootNode: ReactNode): RenderResult {
   return {
     toJSON: () => toJSON(rootNode),
+    findAll: (predicate: ReactNode => boolean) => findAll(rootNode, predicate),
   };
 }
 
@@ -61,7 +62,7 @@ export function render(element: Element<ElementType>): RenderResult {
   });
 
   // $FlowFixMe
-  const root: RootReactNode = manager.getRoot(containerTag);
+  const root: [ReactNode] = manager.getRoot(containerTag);
 
   if (root == null) {
     throw new Error('No root found for containerTag ' + containerTag);
@@ -94,3 +95,22 @@ function toJSON(node: ReactNode): RenderedJSON {
 
   return json;
 }
+
+function findAll(
+  node: ReactNode,
+  predicate: ReactNode => boolean,
+): Array<ReactNode> {
+  const results = [];
+
+  if (predicate(node)) {
+    results.push(node);
+  }
+
+  if (node.children != null && node.children.length > 0) {
+    for (const child of node.children) {
+      results.push(...findAll(child, predicate));
+    }
+  }
+
+  return results;
+}