test: 💍 add useSearchParam tests

src/__tests__/useSearchParam.test.ts

@@ -0,0 +1,51 @@
+import { act, renderHook } from '@testing-library/react-hooks';
+import useSearchParam from '../useSearchParam';
+
+(global as any).window = Object.create(window);
+const location = {
+  search: 'foo=bar&baz=quux',
+};
+Object.defineProperty(window, 'location', {
+  value: location,
+});
+
+it('returns current location.search value', () => {
+  location.search = 'foo=bar&baz=quux';
+
+  const { result } = renderHook(() => useSearchParam('foo'));
+
+  expect(result.current).toBe('bar');
+});
+
+it('returns null if search param not found', () => {
+  location.search = 'foo=bar&baz=quux';
+
+  const { result } = renderHook(() => useSearchParam('foo2'));
+
+  expect(result.current).toBe(null);
+});
+
+it('tracks the latest search param value', () => {
+  location.search = 'foo=bar&baz=quux';
+
+  let callback;
+  const window$addEventListener = window.addEventListener;
+  window.addEventListener = (event, cb) => {
+    if (event === 'pushstate') {
+      callback = cb;
+    }
+  };
+
+  const { result } = renderHook(() => useSearchParam('baz'));
+
+  expect(result.current).toBe('quux');
+
+  act(() => {
+    location.search = 'foo=1&baz=2';
+    callback();
+  });
+
+  expect(result.current).toBe('2');
+
+  window.addEventListener = window$addEventListener;
+});