Add tests for CartEventProvider

assets/js/base/context/providers/cart-checkout/cart-events/test/index.tsx

@@ -0,0 +1,45 @@
+/**
+ * External dependencies
+ */
+import { useCartEventsContext } from '@woocommerce/base-context';
+import { useEffect } from '@wordpress/element';
+import { render, screen, waitFor } from '@testing-library/react';
+
+/**
+ * Internal dependencies
+ */
+import { CartEventsProvider } from '../index';
+import Block from '../../../../../../blocks/cart/inner-blocks/proceed-to-checkout-block/block';
+
+describe( 'CartEventsProvider', () => {
+	it( 'allows observers to unsubscribe', async () => {
+		const mockObserver = jest.fn();
+		const MockObserverComponent = () => {
+			const { onProceedToCheckout } = useCartEventsContext();
+			useEffect( () => {
+				const unsubscribe = onProceedToCheckout( () => {
+					mockObserver();
+					unsubscribe();
+				} );
+			}, [ onProceedToCheckout ] );
+			return <div>Mock observer</div>;
+		};
+
+		render(
+			<CartEventsProvider>
+				<div>
+					<MockObserverComponent />
+					<Block checkoutPageId={ 0 } className="test-block" />
+				</div>
+			</CartEventsProvider>
+		);
+		expect( screen.getByText( 'Mock observer' ) ).toBeInTheDocument();
+		const button = screen.getByText( 'Proceed to Checkout' );
+		// Click twice. The observer should unsubscribe after the first click.
+		button.click();
+		button.click();
+		await waitFor( () => {
+			expect( mockObserver ).toHaveBeenCalledTimes( 1 );
+		} );
+	} );
+} );