usePrevious tests

src/__tests__/usePrevious.test.tsx

@@ -0,0 +1,22 @@
+import { cleanup, renderHook } from 'react-hooks-testing-library';
+import usePrevious from '../usePrevious';
+
+afterEach(cleanup);
+
+describe('usePrevious', () => {
+  it('should be defined', () => {
+    expect(usePrevious).toBeDefined();
+  });
+
+  const hook = renderHook(props => usePrevious(props), { initialProps: 0 });
+
+  it('should return undefined on initial render', () => {
+    expect(hook.result.current).toBe(undefined);
+  });
+
+  it('should return previous state after update', () => {
+    hook.rerender(1);
+    hook.rerender(2);
+    expect(hook.result.current).toBe(1);
+  });
+});