From a6d4eed534cbbc480577fd52be19d669af679af4 Mon Sep 17 00:00:00 2001
From: Brian Vaughn <bvaughn@fb.com>
Date: Fri, 6 Mar 2020 15:03:18 -0800
Subject: [PATCH] Added new failing tests (pending a separate fix to React)

---
 .../useMutableSource-test.internal.js         | 92 +++++++++++++++++++
 1 file changed, 92 insertions(+)

diff --git a/packages/react-reconciler/src/__tests__/useMutableSource-test.internal.js b/packages/react-reconciler/src/__tests__/useMutableSource-test.internal.js
index 3dc1539f7aa5f..3d875ffc89dc4 100644
--- a/packages/react-reconciler/src/__tests__/useMutableSource-test.internal.js
+++ b/packages/react-reconciler/src/__tests__/useMutableSource-test.internal.js
@@ -809,6 +809,39 @@ describe('useMutableSource', () => {
       });
     });
 
+    it('should recover from a mutation during yield when other work is scheduled', () => {
+      const source = createSource('one');
+      const mutableSource = createMutableSource(source);
+
+      act(() => {
+        // Start a render that uses the mutable source.
+        ReactNoop.render(
+          <>
+            <Component
+              label="a"
+              getSnapshot={defaultGetSnapshot}
+              mutableSource={mutableSource}
+              subscribe={defaultSubscribe}
+            />
+            <Component
+              label="b"
+              getSnapshot={defaultGetSnapshot}
+              mutableSource={mutableSource}
+              subscribe={defaultSubscribe}
+            />
+          </>,
+        );
+        expect(Scheduler).toFlushAndYieldThrough(['a:one']);
+
+        // Mutate source
+        source.value = 'two';
+
+        // Now render something different.
+        ReactNoop.render(<div />);
+        expect(Scheduler).toFlushAndYield([]);
+      });
+    });
+
     it('should not throw if the new getSnapshot returns the same snapshot value', () => {
       const source = createSource('one');
       const mutableSource = createMutableSource(source);
@@ -1311,6 +1344,65 @@ describe('useMutableSource', () => {
             ).toThrow('Invalid hook call');
           });
         });
+
+        it('should error if multiple renderers of the same type use a mutable source at the same time with mutation between', () => {
+          const source = createSource('one');
+          const mutableSource = createMutableSource(source);
+
+          act(() => {
+            // Start a render that uses the mutable source.
+            ReactNoop.render(
+              <>
+                <Component
+                  label="a"
+                  getSnapshot={defaultGetSnapshot}
+                  mutableSource={mutableSource}
+                  subscribe={defaultSubscribe}
+                />
+                <Component
+                  label="b"
+                  getSnapshot={defaultGetSnapshot}
+                  mutableSource={mutableSource}
+                  subscribe={defaultSubscribe}
+                />
+              </>,
+            );
+            expect(Scheduler).toFlushAndYieldThrough(['a:one']);
+
+            const PrevScheduler = Scheduler;
+
+            // Get a new copy of ReactNoop.
+            loadModules();
+
+            spyOnDev(console, 'error');
+
+            // Mutate before the new render reads from the source.
+            source.value = 'two';
+
+            // Use the mutablesource again but with a different renderer.
+            ReactNoop.render(
+              <Component
+                label="c"
+                getSnapshot={defaultGetSnapshot}
+                mutableSource={mutableSource}
+                subscribe={defaultSubscribe}
+              />,
+            );
+            expect(Scheduler).toFlushAndYieldThrough(['c:two']);
+
+            expect(console.error.calls.argsFor(0)[0]).toContain(
+              'Detected multiple renderers concurrently rendering the ' +
+                'same mutable source. This is currently unsupported.',
+            );
+
+            // TODO (useMutableSource) Act will automatically flush remaining work from render 1,
+            // but at this point something in the hooks dispatcher has been broken by jest.resetModules()
+            // Figure out what this is and remove this catch.
+            expect(() =>
+              PrevScheduler.unstable_flushAllWithoutAsserting(),
+            ).toThrow('Invalid hook call');
+          });
+        });
       });
     }
   }