tests: useFavicon (#666)

src/__tests__/useFavicon.test.tsx

@@ -0,0 +1,55 @@
+import { renderHook } from '@testing-library/react-hooks';
+import useFavicon from '../useFavicon';
+
+afterEach(() => {
+  const favicon = document.querySelector("link[rel*='icon']");
+  if (favicon) {
+    favicon.remove();
+  }
+});
+
+describe('useFavicon', () => {
+  it('should be defined', () => {
+    expect(useFavicon).toBeDefined();
+  });
+
+  it('should create a HTMLLinkElement', () => {
+    const faviconBeforeHook = document.querySelector("link[rel*='icon']");
+
+    expect(faviconBeforeHook).toBe(null);
+    renderHook(() => useFavicon('My-favicon'));
+
+    const faviconAfterHook = document.querySelector("link[rel*='icon']");
+    expect(faviconAfterHook).toBeInstanceOf(HTMLLinkElement);
+  });
+
+  it('should set the elements type to "image/x-icon"', () => {
+    renderHook(() => useFavicon('My-favicon'));
+    const favicon = document.querySelector("link[rel*='icon']") as HTMLLinkElement;
+
+    expect(favicon.type).toBe('image/x-icon');
+  });
+
+  it('should set the elements rel to "shortcut icon"', () => {
+    renderHook(() => useFavicon('My-favicon'));
+    const favicon = document.querySelector("link[rel*='icon']") as HTMLLinkElement;
+
+    expect(favicon.rel).toBe('shortcut icon');
+  });
+
+  it('should set the elements href to the provided string', () => {
+    renderHook(() => useFavicon('https://github.com/streamich/react-use'));
+    const favicon = document.querySelector("link[rel*='icon']") as HTMLLinkElement;
+
+    expect(favicon.href).toBe('https://github.com/streamich/react-use');
+  });
+
+  it('should update an existing favicon', () => {
+    const hook = renderHook(props => useFavicon(props), { initialProps: 'https://github.com/streamich/react-use' });
+    const favicon = document.querySelector("link[rel*='icon']") as HTMLLinkElement;
+
+    expect(favicon.href).toBe('https://github.com/streamich/react-use');
+    hook.rerender('https://en.wikipedia.org/wiki/Favicon');
+    expect(favicon.href).toBe('https://en.wikipedia.org/wiki/Favicon');
+  });
+});