Basic partial hydration test

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

@@ -0,0 +1,73 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ *
+ * @emails react-core
+ */
+
+'use strict';
+
+let React;
+let ReactDOM;
+let ReactDOMServer;
+let ReactFeatureFlags;
+let Suspense;
+
+describe('ReactDOMServerPartialHydration', () => {
+  beforeEach(() => {
+    jest.resetModuleRegistry();
+
+    ReactFeatureFlags = require('shared/ReactFeatureFlags');
+    ReactFeatureFlags.enableSuspenseServerRenderer = true;
+
+    React = require('react');
+    ReactDOM = require('react-dom');
+    ReactDOMServer = require('react-dom/server');
+    Suspense = React.Suspense;
+  });
+
+  it('hydrates a parent even if a child Suspense boundary is blocked', () => {
+    let suspend = false;
+    let resolve;
+    let promise = new Promise(resolvePromise => (resolve = resolvePromise));
+
+    function Child() {
+      if (suspend) {
+        throw promise;
+      } else {
+        return 'Hello';
+      }
+    }
+
+    function App() {
+      return (
+        <div>
+          <Suspense fallback="Loading...">
+            <span>
+              <Child />
+            </span>
+          </Suspense>
+        </div>
+      );
+    }
+
+    // First we render the final HTML. With the streaming renderer
+    // this may have suspense points on the server but here we want
+    // to test the completed HTML. Don't suspend on the server.
+    suspend = false;
+    let finalHTML = ReactDOMServer.renderToString(<App />);
+
+    let container = document.createElement('div');
+    container.innerHTML = finalHTML;
+
+    // On the client we don't have all data yet but we want to start
+    // hydrating anyway.
+    suspend = true;
+    ReactDOM.hydrate(<App />, container);
+
+    // Resolving the promise should continue hydration
+    resolve();
+  });
+});