Update test comments with explanations

Author: rickhanlonii

packages/react-reconciler/src/__tests__/ReactHooksWithNoopRenderer-test.js

@@ -166,7 +166,6 @@ describe('ReactHooksWithNoopRenderer', () => {
     // Schedule some updates
     if (gate(flags => flags.enableSyncDefaultUpdates)) {
       React.startTransition(() => {
-        // TODO: Batched updates need to be inside startTransition?
         ReactNoop.batchedUpdates(() => {
           counter.current.updateCount(1);
           counter.current.updateCount(count => count + 10);

packages/react-reconciler/src/__tests__/ReactIncrementalScheduling-test.js

@@ -287,12 +287,12 @@ describe('ReactIncrementalScheduling', () => {
         instance.setState({tick: 2});
       });
 
-      // TODO: why does this flush sync?
       expect(Scheduler).toFlushAndYieldThrough([
         'render: 2',
         'componentDidUpdate: 2',
         'componentDidUpdate (before setState): 2',
         'componentDidUpdate (after setState): 2',
+        // This renders because the scheduled update is default, which is sync.
         'render: 3',
         'componentDidUpdate: 3',
       ]);

packages/react-reconciler/src/__tests__/ReactIncrementalUpdates-test.js

@@ -196,11 +196,13 @@ describe('ReactIncrementalUpdates', () => {
       // Now flush the remaining work. Even though e and f were already processed,
       // they should be processed again, to ensure that the terminal state
       // is deterministic.
-      // TODO: should d, e, f be flushed again first?
       expect(Scheduler).toFlushAndYield([
+        // Since 'g' is in a transition, we'll process 'd' separately first.
+        // That causes us to process 'd' with 'e' and 'f' rebased.
         'd',
         'e',
         'f',
+        // Then we'll re-process everything for 'g'.
         'a',
         'b',
         'c',
@@ -290,18 +292,19 @@ describe('ReactIncrementalUpdates', () => {
       });
 
       // The sync updates should have flushed, but not the async ones.
-      // TODO: should 'd' have flushed?
-      // TODO: should 'f' have flushed? I don't know what enqueueReplaceState is.
       expect(Scheduler).toHaveYielded(['e', 'f']);
       expect(ReactNoop.getChildren()).toEqual([span('f')]);
 
       // Now flush the remaining work. Even though e and f were already processed,
       // they should be processed again, to ensure that the terminal state
       // is deterministic.
       expect(Scheduler).toFlushAndYield([
+        // Since 'g' is in a transition, we'll process 'd' separately first.
+        // That causes us to process 'd' with 'e' and 'f' rebased.
         'd',
         'e',
         'f',
+        // Then we'll re-process everything for 'g'.
         'a',
         'b',
         'c',