feat: option for enabling concurrent rendering

.github/workflows/ci.yml

@@ -56,11 +56,26 @@ jobs:
         uses: ./.github/actions/setup-deps
 
       - name: Test
-        run: yarn test:ci
+        run: yarn test:ci:coverage
 
       - name: Upload coverage to Codecov
         uses: codecov/codecov-action@v4
 
+
+  test-concurrent:
+    needs: [install-cache-deps]
+    runs-on: ubuntu-latest
+    name: Test (concurrent mode)
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup Node.js and deps
+        uses: ./.github/actions/setup-deps
+
+      - name: Test in concurrent mode
+        run: CONCURRENT_MODE=1 yarn test:ci
+
   test-website:
     runs-on: ubuntu-latest
     name: Test Website

jest-setup.ts

@@ -1,6 +1,9 @@
-import { resetToDefaults } from './src/pure';
+import { resetToDefaults, configure } from './src/pure';
 import './src/matchers/extend-expect';
 
 beforeEach(() => {
   resetToDefaults();
+  if (process.env.CONCURRENT_MODE === '1') {
+    configure({ concurrentRoot: true });
+  }
 });

package.json

@@ -25,7 +25,8 @@
   "scripts": {
     "clean": "del build",
     "test": "jest",
-    "test:ci": "jest --maxWorkers=2 --collectCoverage=true --coverage-provider=v8",
+    "test:ci": "jest --maxWorkers=2",
+    "test:ci:coverage": "jest --maxWorkers=2 --collectCoverage=true --coverage-provider=v8",
     "typecheck": "tsc",
     "copy-flowtypes": "cp typings/index.flow.js build",
     "lint": "eslint src --cache",

src/__tests__/config.test.ts

@@ -1,5 +1,9 @@
 import { getConfig, configure, resetToDefaults, configureInternal } from '../config';
 
+beforeEach(() => {
+  resetToDefaults();
+});
+
 test('getConfig() returns existing configuration', () => {
   expect(getConfig().asyncUtilTimeout).toEqual(1000);
   expect(getConfig().defaultIncludeHiddenElements).toEqual(false);
@@ -12,6 +16,7 @@ test('configure() overrides existing config values', () => {
     asyncUtilTimeout: 5000,
     defaultDebugOptions: { message: 'debug message' },
     defaultIncludeHiddenElements: false,
+    concurrentRoot: false,
   });
 });
 

src/__tests__/render.test.tsx

@@ -241,3 +241,13 @@ test('render calls detects host component names', () => {
   render(<View testID="test" />);
   expect(getConfig().hostComponentNames).not.toBeUndefined();
 });
+
+test('supports legacy rendering', () => {
+  render(<View testID="test" />, { concurrentRoot: false });
+  expect(screen.root).toBeDefined();
+});
+
+test('supports concurrent rendering', () => {
+  render(<View testID="test" />, { concurrentRoot: true });
+  expect(screen.root).toBeDefined();
+});

src/config.ts

@@ -13,6 +13,12 @@ export type Config = {
 
   /** Default options for `debug` helper. */
   defaultDebugOptions?: Partial<DebugOptions>;
+
+  /**
+   * Set to `true` to enable concurrent rendering.
+   * Otherwise `render` will default to legacy synchronous rendering.
+   */
+  concurrentRoot: boolean;
 };
 
 export type ConfigAliasOptions = {
@@ -37,6 +43,7 @@ export type InternalConfig = Config & {
 const defaultConfig: InternalConfig = {
   asyncUtilTimeout: 1000,
   defaultIncludeHiddenElements: false,
+  concurrentRoot: false,
 };
 
 let config = { ...defaultConfig };

src/render.tsx

@@ -1,4 +1,8 @@
-import type { ReactTestInstance, ReactTestRenderer } from 'react-test-renderer';
+import type {
+  ReactTestInstance,
+  ReactTestRenderer,
+  TestRendererOptions,
+} from 'react-test-renderer';
 import * as React from 'react';
 import { Profiler } from 'react';
 import act from './act';
@@ -14,7 +18,18 @@ import { setRenderResult } from './screen';
 import { getQueriesForElement } from './within';
 
 export interface RenderOptions {
+  /**
+   * Pass a React Component as the wrapper option to have it rendered around the inner element. This is most useful for creating
+   *  reusable custom render functions for common data providers.
+   */
   wrapper?: React.ComponentType<any>;
+
+  /**
+   * Set to `true` to enable concurrent rendering.
+   * Otherwise `render` will default to legacy synchronous rendering.
+   */
+  concurrentRoot?: boolean | undefined;
+
   createNodeMock?: (element: React.ReactElement) => unknown;
   unstable_validateStringsRenderedWithinText?: boolean;
 }
@@ -39,11 +54,18 @@ export function renderInternal<T>(
 ) {
   const {
     wrapper: Wrapper,
+    concurrentRoot,
     detectHostComponentNames = true,
     unstable_validateStringsRenderedWithinText,
-    ...testRendererOptions
+    ...rest
   } = options || {};
 
+  const testRendererOptions: TestRendererOptions = {
+    ...rest,
+    // @ts-expect-error incomplete typing on RTR package
+    unstable_isConcurrent: concurrentRoot ?? getConfig().concurrentRoot,
+  };
+
   if (detectHostComponentNames) {
     configureHostComponentNamesIfNeeded();
   }

website/docs/12.x/docs/api/misc/config.mdx

@@ -7,6 +7,7 @@ type Config = {
   asyncUtilTimeout: number;
   defaultHidden: boolean;
   defaultDebugOptions: Partial<DebugOptions>;
+  concurrentRoot: boolean;
 };
 
 function configure(options: Partial<Config>) {}
@@ -26,6 +27,10 @@ This option is also available as `defaultHidden` alias for compatibility with [R
 
 Default [debug options](#debug) to be used when calling `debug()`. These default options will be overridden by the ones you specify directly when calling `debug()`.
 
+### `concurrentRoot` option
+
+Set to `true` to enable concurrent rendering used in the React Native New Architecture. Otherwise `render` will default to legacy synchronous rendering.
+
 ## `resetToDefaults()`
 
 ```ts

website/docs/12.x/docs/api/render.mdx

@@ -32,6 +32,10 @@ wrapper?: React.ComponentType<any>,
 
 This option allows you to wrap the tested component, passed as the first option to the `render()` function, in an additional wrapper component. This is useful for creating reusable custom render functions for common React Context providers.
 
+#### `concurrentRoot` option
+
+Set to `true` to enable concurrent rendering used in the React Native New Architecture. Otherwise `render` will default to legacy synchronous rendering.
+
 #### `createNodeMock` option
 
 ```ts