Convert ReactMountDestruction (partially) to createRoot (#28004)

packages/react-dom/src/__tests__/ReactDOMRoot-test.js

@@ -133,6 +133,13 @@ describe('ReactDOMRoot', () => {
     expect(container.textContent).toEqual('');
   });
 
+  it('can be immediately unmounted', async () => {
+    const root = ReactDOMClient.createRoot(container);
+    await act(() => {
+      root.unmount();
+    });
+  });
+
   it('supports hydration', async () => {
     const markup = await new Promise(resolve =>
       resolve(
@@ -392,6 +399,18 @@ describe('ReactDOMRoot', () => {
     }
   });
 
+  it('throws if unmounting a root that has had its contents removed', async () => {
+    const root = ReactDOMClient.createRoot(container);
+    await act(() => {
+      root.render(<div>Hi</div>);
+    });
+    container.innerHTML = '';
+
+    expect(() => {
+      root.unmount();
+    }).toThrow('The node to be removed is not a child of this node.');
+  });
+
   it('opts-in to concurrent default updates', async () => {
     const root = ReactDOMClient.createRoot(container, {
       unstable_concurrentUpdatesByDefault: true,

packages/react-dom/src/__tests__/ReactMountDestruction-test.js

@@ -11,31 +11,42 @@
 
 const React = require('react');
 const ReactDOM = require('react-dom');
+const ReactDOMClient = require('react-dom/client');
+const act = require('internal-test-utils').act;
 
 describe('ReactMount', () => {
-  it('should destroy a react root upon request', () => {
+  it('should destroy a react root upon request', async () => {
     const mainContainerDiv = document.createElement('div');
     document.body.appendChild(mainContainerDiv);
 
     const instanceOne = <div className="firstReactDiv" />;
     const firstRootDiv = document.createElement('div');
     mainContainerDiv.appendChild(firstRootDiv);
-    ReactDOM.render(instanceOne, firstRootDiv);
+    const firstRoot = ReactDOMClient.createRoot(firstRootDiv);
+    await act(() => {
+      firstRoot.render(instanceOne);
+    });
 
     const instanceTwo = <div className="secondReactDiv" />;
     const secondRootDiv = document.createElement('div');
     mainContainerDiv.appendChild(secondRootDiv);
-    ReactDOM.render(instanceTwo, secondRootDiv);
+    const secondRoot = ReactDOMClient.createRoot(secondRootDiv);
+    await act(() => {
+      secondRoot.render(instanceTwo);
+    });
 
     // Test that two react roots are rendered in isolation
     expect(firstRootDiv.firstChild.className).toBe('firstReactDiv');
     expect(secondRootDiv.firstChild.className).toBe('secondReactDiv');
 
     // Test that after unmounting each, they are no longer in the document.
-    ReactDOM.unmountComponentAtNode(firstRootDiv);
+    await act(() => {
+      firstRoot.unmount();
+    });
     expect(firstRootDiv.firstChild).toBeNull();
-    ReactDOM.unmountComponentAtNode(secondRootDiv);
-    expect(secondRootDiv.firstChild).toBeNull();
+    await act(() => {
+      secondRoot.unmount();
+    });
   });
 
   it('should warn when unmounting a non-container root node', () => {
@@ -46,6 +57,7 @@ describe('ReactMount', () => {
         <div />
       </div>
     );
+    // Cannot be migrated to createRoot until we remove unmountComponentAtNode i.e. remove this test.
     ReactDOM.render(component, mainContainerDiv);
 
     // Test that unmounting at a root node gives a helpful warning
@@ -69,6 +81,7 @@ describe('ReactMount', () => {
         </div>
       </div>
     );
+    // Cannot be migrated to createRoot until we remove unmountComponentAtNode i.e. remove this test.
     ReactDOM.render(component, mainContainerDiv);
 
     // Test that unmounting at a non-root node gives a different warning