test: Add tests for useEffect & useState w/ NaN

Co-authored-by: jayrobin <[email protected]>

hooks/test/browser/useEffect.test.js

@@ -636,4 +636,26 @@ describe('useEffect', () => {
 		expect(calls.length).to.equal(1);
 		expect(calls).to.deep.equal(['doing effecthi']);
 	});
+
+	it('should not rerun when receiving NaN on subsequent renders', () => {
+		const calls = [];
+		const Component = ({ value }) => {
+			const [count, setCount] = useState(0);
+			useEffect(() => {
+				calls.push('doing effect' + count);
+				setCount(count + 1);
+				return () => {
+					calls.push('cleaning up' + count);
+				};
+			}, [value]);
+			return <p>{count}</p>;
+		};
+		const App = () => <Component value={NaN} />;
+
+		act(() => {
+			render(<App />, scratch);
+		});
+		expect(calls.length).to.equal(1);
+		expect(calls).to.deep.equal(['doing effect0']);
+	});
 });

hooks/test/browser/useState.test.js

@@ -372,6 +372,32 @@ describe('useState', () => {
 		expect(scratch.innerHTML).to.equal('<p>hello world!!!</p>');
 	});
 
+	it('should limit rerenders when setting state to NaN', () => {
+		const calls = [];
+		const App = ({ i }) => {
+			calls.push('rendering' + i);
+			const [greeting, setGreeting] = useState(0);
+
+			if (i === 2) {
+				setGreeting(NaN);
+			}
+
+			return <p>{greeting}</p>;
+		};
+
+		act(() => {
+			render(<App i={1} />, scratch);
+		});
+		expect(calls.length).to.equal(1);
+		expect(calls).to.deep.equal(['rendering1']);
+
+		act(() => {
+			render(<App i={2} />, scratch);
+		});
+		expect(calls.length).to.equal(3);
+		expect(calls.slice(1).every(c => c === 'rendering2')).to.equal(true);
+	});
+
 	describe('Global sCU', () => {
 		let prevScu;
 		before(() => {