Fix false "unknown property" warnings for events in SSR (#10272)

* Reset modules between importing client and server modules in the test

Client and server renderers still share some modules, including injections.
This means they have shared state in this test, potentially missing issues that would occur in real world.

After this change, the client and server modules are completely isolated in the test.
This makes the tests fail due to #10265 (a real issue that was missed).

* Don't validate events if no plugins are injected

Author: gaearon

src/renderers/dom/shared/__tests__/ReactDOMServerIntegration-test.js

@@ -281,28 +281,47 @@ function expectMarkupMismatch(serverElement, clientElement) {
   return testMarkupMatch(serverElement, clientElement, false);
 }
 
+// TODO: this is a hack for testing dynamic injection. Remove this when we decide
+// how to do static injection instead.
+let onAfterResetModules = null;
+
 // When there is a test that renders on server and then on client and expects a logged
 // error, you want to see the error show up both on server and client. Unfortunately,
 // React refuses to issue the same error twice to avoid clogging up the console.
 // To get around this, we must reload React modules in between server and client render.
-let onAfterResetModules = null;
 function resetModules() {
+  // First, reset the modules to load the client renderer.
   jest.resetModuleRegistry();
+  if (typeof onAfterResetModules === 'function') {
+    onAfterResetModules();
+  }
+
+  // TODO: can we express this test with only public API?
+  ExecutionEnvironment = require('ExecutionEnvironment');
+
   PropTypes = require('prop-types');
   React = require('react');
   ReactDOM = require('react-dom');
-  ReactDOMServer = require('react-dom/server');
   ReactDOMFeatureFlags = require('ReactDOMFeatureFlags');
-  ReactDOMNodeStream = require('react-dom/node-stream');
   ReactTestUtils = require('react-dom/test-utils');
-  // TODO: can we express this test with only public API?
-  ExecutionEnvironment = require('ExecutionEnvironment');
 
-  // TODO: this is a hack for testing dynamic injection. Remove this when we decide
-  // how to do static injection instead.
+  // Now we reset the modules again to load the server renderer.
+  // Resetting is important because we want to avoid any shared state
+  // influencing the tests.
+  jest.resetModuleRegistry();
+  if (typeof onAfterResetModules === 'function') {
+    onAfterResetModules();
+  }
+
+  ReactDOMServer = require('react-dom/server');
+
+  // Finally, reset modules one more time before importing the stream renderer.
+  jest.resetModuleRegistry();
   if (typeof onAfterResetModules === 'function') {
     onAfterResetModules();
   }
+
+  ReactDOMNodeStream = require('react-dom/node-stream');
 }
 
 describe('ReactDOMServerIntegration', () => {

src/renderers/dom/shared/hooks/ReactDOMUnknownPropertyHook.js

@@ -67,6 +67,11 @@ if (__DEV__) {
     if (EventPluginRegistry.registrationNameModules.hasOwnProperty(name)) {
       return true;
     }
+    if (EventPluginRegistry.plugins.length === 0 && name.indexOf('on') === 0) {
+      // If no event plugins have been injected, we might be in a server environment.
+      // Don't check events in this case.
+      return true;
+    }
     warnedProperties[name] = true;
     var lowerCasedName = name.toLowerCase();