Add failing test for facebook#16215

Next commit fixes it.

packages/react-reconciler/src/__tests__/ReactSuspenseCallback-test.internal.js

@@ -238,4 +238,71 @@ describe('ReactSuspense', () => {
     expect(ops1).toEqual([]);
     expect(ops2).toEqual([]);
   });
+
+  it('regression test for #16215 that relies on implementation details', async () => {
+    // Regression test for https://github.com/facebook/react/pull/16215.
+    // The bug only happens if there's an error earlier in the commit phase.
+    // The first error is the one that gets thrown, so to observe the later
+    // error, I've mocked the ReactErrorUtils module.
+    //
+    // If this test starts failing because the implementation details change,
+    // you can probably just delete it. It's not worth the hassle.
+    jest.resetModules();
+
+    let errors = [];
+    let hasCaughtError = false;
+    jest.mock('shared/ReactErrorUtils', () => ({
+      invokeGuardedCallback(name, fn, context, ...args) {
+        try {
+          return fn.call(context, ...args);
+        } catch (error) {
+          hasCaughtError = true;
+          errors.push(error);
+        }
+      },
+      hasCaughtError() {
+        return hasCaughtError;
+      },
+      clearCaughtError() {
+        hasCaughtError = false;
+        return errors[errors.length - 1];
+      },
+    }));
+
+    ReactFeatureFlags = require('shared/ReactFeatureFlags');
+    ReactFeatureFlags.enableSuspenseCallback = true;
+
+    React = require('react');
+    ReactNoop = require('react-noop-renderer');
+    Scheduler = require('scheduler');
+
+    const {useEffect} = React;
+    const {PromiseComp} = createThenable();
+    function App() {
+      useEffect(() => {
+        Scheduler.unstable_yieldValue('Passive Effect');
+      });
+      return (
+        <React.Fragment>
+          <React.Suspense
+            suspenseCallback={() => {
+              throw Error('Oops!');
+            }}
+            fallback="Loading...">
+            <PromiseComp />
+          </React.Suspense>
+        </React.Fragment>
+      );
+    }
+    const root = ReactNoop.createRoot();
+    await ReactNoop.act(async () => {
+      root.render(<App />);
+      expect(Scheduler).toFlushAndThrow('Oops!');
+    });
+
+    // Should have only received a single error. Before the bug fix, there was
+    // also a second error related to the Suspense update queue.
+    expect(errors.length).toBe(1);
+    expect(errors[0].message).toEqual('Oops!');
+  });
 });