[tests] Assert scheduler log empty in internalAct

Author: rickhanlonii

packages/internal-test-utils/internalAct.js

@@ -45,6 +45,15 @@ export async function act<T>(scope: () => Thenable<T>): Thenable<T> {
     );
   }
 
+  const actualYields = Scheduler.unstable_clearLog();
+  if (actualYields.length !== 0) {
+    const error = Error(
+      'Log of yielded values is not empty. ' + 'Call assertLog first.',
+    );
+    Error.captureStackTrace(error, act);
+    throw error;
+  }
+
   // $FlowFixMe[cannot-resolve-name]: Flow doesn't know about global Jest object
   if (!jest.isMockFunction(setTimeout)) {
     throw Error(