fix(5018): add tests to check if text is updated once

test/runtime/samples/component-event-handler-contenteditable/_config.js

@@ -0,0 +1,15 @@
+export default {
+	html: `
+		<div contenteditable=""></div>
+	`,
+
+	async test({ assert, component, target, window }) {
+		const div = target.querySelector('div');
+		const text =  window.document.createTextNode('a');
+		div.insertBefore(text, null);
+		const event = new window.InputEvent('input');
+		await div.dispatchEvent(event);
+
+		assert.equal(div.textContent, 'a');
+	}
+};

test/runtime/samples/component-event-handler-contenteditable/main.svelte

@@ -0,0 +1,6 @@
+<script>
+	let text = '';
+	const updater = (event) => {text = event.target.textContent}
+</script>
+
+<div contenteditable on:input={updater}>{text}</div>