Add tests for useElementRef

src/shared/test/hooks-test.js

@@ -0,0 +1,32 @@
+import { render } from 'preact';
+
+import { useElementRef } from '../hooks';
+
+describe('shared/hooks', () => {
+  it('returns ref if accessed when non-null', () => {
+    function Widget({ callback }) {
+      const ref = useElementRef(HTMLButtonElement);
+      return (
+        <button ref={ref} onClick={() => callback(ref.current.localName)} />
+      );
+    }
+
+    const callback = sinon.stub();
+    const container = document.createElement('div');
+    render(<Widget callback={callback} />, container);
+    container.querySelector('button').click();
+
+    assert.calledWith(callback, 'button');
+  });
+
+  it('throws if accessed when `null`', () => {
+    function Widget() {
+      const ref = useElementRef(HTMLElement);
+      return <div>{ref.current.localName}</div>;
+    }
+
+    assert.throws(() => {
+      render(<Widget />, document.createElement('div'));
+    }, 'Tried to access null ref');
+  });
+});