Only concurrent render in RTR

Author: Jack Pope

packages/react-reconciler/src/__tests__/ErrorBoundaryReconciliation-test.internal.js

@@ -46,45 +46,40 @@ describe('ErrorBoundaryReconciliation', () => {
       fail ? <InvalidType /> : <span prop="BrokenRender" />;
   });
 
-  [true, false].forEach(isConcurrent => {
-    async function sharedTest(ErrorBoundary, fallbackTagName) {
-      let renderer;
+  async function sharedTest(ErrorBoundary, fallbackTagName) {
+    let renderer;
 
+    await act(() => {
+      renderer = ReactTestRenderer.create(
+        <ErrorBoundary fallbackTagName={fallbackTagName}>
+          <BrokenRender fail={false} />
+        </ErrorBoundary>,
+        {unstable_isConcurrent: true},
+      );
+    });
+    expect(renderer).toMatchRenderedOutput(<span prop="BrokenRender" />);
+    await expect(async () => {
       await act(() => {
-        renderer = ReactTestRenderer.create(
+        renderer.update(
           <ErrorBoundary fallbackTagName={fallbackTagName}>
-            <BrokenRender fail={false} />
+            <BrokenRender fail={true} />
           </ErrorBoundary>,
-          {unstable_isConcurrent: isConcurrent},
         );
       });
-      expect(renderer).toMatchRenderedOutput(<span prop="BrokenRender" />);
-
-      await expect(async () => {
-        await act(() => {
-          renderer.update(
-            <ErrorBoundary fallbackTagName={fallbackTagName}>
-              <BrokenRender fail={true} />
-            </ErrorBoundary>,
-          );
-        });
-      }).toErrorDev(isConcurrent ? ['invalid', 'invalid'] : ['invalid']);
-      const Fallback = fallbackTagName;
-      expect(renderer).toMatchRenderedOutput(<Fallback prop="ErrorBoundary" />);
-    }
+    }).toErrorDev(['invalid', 'invalid']);
+    const Fallback = fallbackTagName;
+    expect(renderer).toMatchRenderedOutput(<Fallback prop="ErrorBoundary" />);
+  }
 
-    describe(isConcurrent ? 'concurrent' : 'sync', () => {
-      it('componentDidCatch can recover by rendering an element of the same type', () =>
-        sharedTest(DidCatchErrorBoundary, 'span'));
+  it('componentDidCatch can recover by rendering an element of the same type', () =>
+    sharedTest(DidCatchErrorBoundary, 'span'));
 
-      it('componentDidCatch can recover by rendering an element of a different type', () =>
-        sharedTest(DidCatchErrorBoundary, 'div'));
+  it('componentDidCatch can recover by rendering an element of a different type', () =>
+    sharedTest(DidCatchErrorBoundary, 'div'));
 
-      it('getDerivedStateFromError can recover by rendering an element of the same type', () =>
-        sharedTest(GetDerivedErrorBoundary, 'span'));
+  it('getDerivedStateFromError can recover by rendering an element of the same type', () =>
+    sharedTest(GetDerivedErrorBoundary, 'span'));
 
-      it('getDerivedStateFromError can recover by rendering an element of a different type', () =>
-        sharedTest(GetDerivedErrorBoundary, 'div'));
-    });
-  });
+  it('getDerivedStateFromError can recover by rendering an element of a different type', () =>
+    sharedTest(GetDerivedErrorBoundary, 'div'));
 });

packages/react-reconciler/src/__tests__/ReactLazy-test.internal.js

@@ -1451,6 +1451,7 @@ describe('ReactLazy', () => {
   });
 
   describe('legacy mode', () => {
+    // @gate !disableLegacyMode
     it('mount and reorder lazy elements (legacy mode)', async () => {
       class Child extends React.Component {
         componentDidMount() {
@@ -1520,6 +1521,7 @@ describe('ReactLazy', () => {
       expect(root).toMatchRenderedOutput('ba');
     });
 
+    // @gate !disableLegacyMode
     it('mount and reorder lazy types (legacy mode)', async () => {
       class Child extends React.Component {
         componentDidMount() {

packages/react-test-renderer/src/ReactTestRenderer.js

@@ -55,6 +55,7 @@ import {ConcurrentRoot, LegacyRoot} from 'react-reconciler/src/ReactRootTags';
 import {
   allowConcurrentByDefault,
   enableReactTestRendererWarning,
+  disableLegacyMode,
 } from 'shared/ReactFeatureFlags';
 
 const act = React.act;
@@ -485,16 +486,19 @@ function create(
   }
 
   let createNodeMock = defaultTestOptions.createNodeMock;
-  let isConcurrent = false;
+  const isConcurrentOnly =
+    disableLegacyMode === true &&
+    global.IS_REACT_NATIVE_TEST_ENVIRONMENT !== true;
+  let isConcurrent = isConcurrentOnly;
   let isStrictMode = false;
   let concurrentUpdatesByDefault = null;
   if (typeof options === 'object' && options !== null) {
     if (typeof options.createNodeMock === 'function') {
       // $FlowFixMe[incompatible-type] found when upgrading Flow
       createNodeMock = options.createNodeMock;
     }
-    if (options.unstable_isConcurrent === true) {
-      isConcurrent = true;
+    if (!isConcurrentOnly) {
+      isConcurrent = options.unstable_isConcurrent;
     }
     if (options.unstable_strictMode === true) {
       isStrictMode = true;