Testing: Add E2E test to verify demo errors

test/e2e/specs/demo.test.js

@@ -0,0 +1,20 @@
+/**
+ * Internal dependencies
+ */
+import { visitAdmin } from '../support/utils';
+
+describe( 'new editor state', () => {
+	beforeAll( async () => {
+		await visitAdmin( 'post-new.php', 'gutenberg-demo' );
+	} );
+
+	it( 'should not error', () => {
+		// This test case is intentionally empty. The `beforeAll` lifecycle of
+		// navigating to the Demo page is sufficient assertion in itself, as it
+		// will trigger the global console error capturing if an error occurs
+		// during this process.
+		//
+		// If any other test cases are added which verify expected behavior of
+		// the demo post, this empty test case can be removed.
+	} );
+} );