1 files changed, 59 insertions, 0 deletions
diff --git a/preact/test-utils/test/shared/rerender.test.js b/preact/test-utils/test/shared/rerender.test.js
new file mode 100644
index 0000000..a2e4335
--- /dev/null
+++ b/preact/test-utils/test/shared/rerender.test.js
@@ -0,0 +1,59 @@
+import { options, createElement, render, Component } from 'preact';
+import { teardown, setupRerender } from 'preact/test-utils';
+
+/** @jsx createElement */
+
+describe('setupRerender & teardown', () => {
+	/** @type {HTMLDivElement} */
+	let scratch;
+
+	beforeEach(() => {
+		scratch = document.createElement('div');
+	});
+
+	it('should restore previous debounce', () => {
+		let spy = (options.debounceRendering = sinon.spy());
+
+		setupRerender();
+		teardown();
+
+		expect(options.debounceRendering).to.equal(spy);
+	});
+
+	it('teardown should flush the queue', () => {
+		/** @type {() => void} */
+		let increment;
+		class Counter extends Component {
+			constructor(props) {
+				super(props);
+
+				this.state = { count: 0 };
+				increment = () => this.setState({ count: this.state.count + 1 });
+			}
+
+			render() {
+				return <div>{this.state.count}</div>;
+			}
+		}
+
+		sinon.spy(Counter.prototype, 'render');
+
+		// Setup rerender
+		setupRerender();
+
+		// Initial render
+		render(<Counter />, scratch);
+		expect(Counter.prototype.render).to.have.been.calledOnce;
+		expect(scratch.innerHTML).to.equal('<div>0</div>');
+
+		// queue rerender
+		increment();
+		expect(Counter.prototype.render).to.have.been.calledOnce;
+		expect(scratch.innerHTML).to.equal('<div>0</div>');
+
+		// Pretend test forgot to call rerender. Teardown should do that
+		teardown();
+		expect(Counter.prototype.render).to.have.been.calledTwice;
+		expect(scratch.innerHTML).to.equal('<div>1</div>');
+	});
+});