button things up a bit more

packages/svelte/src/internal/server/dev.js

@@ -50,6 +50,10 @@ function print_error(payload, parent, child) {
 	payload.head.out += `<script>console.error(${JSON.stringify(message)})</script>`;
 }
 
+export function reset_elements() {
+	parent = null;
+}
+
 /**
  * @param {Payload} payload
  * @param {string} tag

packages/svelte/src/internal/server/index.js

@@ -16,6 +16,7 @@ import { current_component, pop, push } from './context.js';
 import { EMPTY_COMMENT, BLOCK_CLOSE, BLOCK_OPEN } from './hydration.js';
 import { validate_store } from '../shared/validate.js';
 import { is_boolean_attribute, is_void } from '../../utils.js';
+import { reset_elements } from './dev.js';
 
 // https://html.spec.whatwg.org/multipage/syntax.html#attributes-2
 // https://infra.spec.whatwg.org/#noncharacter
@@ -100,6 +101,9 @@ export function render(component, options = {}) {
 	on_destroy = [];
 	payload.out += BLOCK_OPEN;
 
+	// prevent parent/child element state being corrupted by a bad render
+	reset_elements();
+
 	if (options.context) {
 		push();
 		/** @type {Component} */ (current_component).c = options.context;

packages/svelte/tests/runtime-legacy/samples/store-dev-mode-error/main.svelte

@@ -2,4 +2,4 @@
 	export let count;
 </script>
 
-<button on:click="{() => count.update(n => n + 1)}">count {$count}</button>
+<button on:click={() => count.update((n) => n + 1)}>count {$count}</button>

packages/svelte/tests/runtime-legacy/shared.ts

@@ -60,6 +60,7 @@ export interface RuntimeTest<Props extends Record<string, any> = Record<string,
 		};
 		logs: any[];
 		warnings: any[];
+		errors: any[];
 		hydrate: Function;
 	}) => void | Promise<void>;
 	test_ssr?: (args: { logs: any[]; assert: Assert }) => void | Promise<void>;
@@ -70,6 +71,7 @@ export interface RuntimeTest<Props extends Record<string, any> = Record<string,
 	error?: string;
 	runtime_error?: string;
 	warnings?: string[];
+	errors?: string[];
 	expect_unhandled_rejections?: boolean;
 	withoutNormalizeHtml?: boolean | 'only-strip-comments';
 	recover?: boolean;
@@ -182,6 +184,7 @@ async function run_test_variant(
 
 	let logs: string[] = [];
 	let warnings: string[] = [];
+	let errors: string[] = [];
 	let manual_hydrate = false;
 
 	{
@@ -220,6 +223,13 @@ async function run_test_variant(
 				}
 			};
 		}
+
+		if (str.slice(0, i).includes('errors') || config.errors) {
+			// eslint-disable-next-line no-console
+			console.error = (...args) => {
+				errors.push(...args);
+			};
+		}
 	}
 
 	try {
@@ -317,15 +327,6 @@ async function run_test_variant(
 
 			config.before_test?.();
 
-			// eslint-disable-next-line no-console
-			const error = console.error;
-			// eslint-disable-next-line no-console
-			console.error = (error) => {
-				if (typeof error === 'string' && error.startsWith('Hydration failed')) {
-					throw new Error(error);
-				}
-			};
-
 			let instance: any;
 			let props: any;
 			let hydrate_fn: Function = () => {
@@ -363,9 +364,6 @@ async function run_test_variant(
 				});
 			}
 
-			// eslint-disable-next-line no-console
-			console.error = error;
-
 			if (config.error) {
 				unintended_error = true;
 				assert.fail('Expected a runtime error');
@@ -401,6 +399,7 @@ async function run_test_variant(
 						compileOptions,
 						logs,
 						warnings,
+						errors,
 						hydrate: hydrate_fn
 					});
 				}
@@ -424,6 +423,14 @@ async function run_test_variant(
 					assert.fail('Received unexpected warnings');
 				}
 
+				if (config.errors) {
+					assert.deepEqual(errors, config.errors);
+				} else if (errors.length && console.error === console_error) {
+					unintended_error = true;
+					console_error.apply(console, errors);
+					assert.fail('Received unexpected errors');
+				}
+
 				assert_html_equal(
 					target.innerHTML,
 					'',

packages/svelte/tests/runtime-runes/samples/invalid-html-ssr/_config.js

@@ -1,12 +1,5 @@
 import { test } from '../../test';
 
-let console_error = console.error;
-
-/**
- * @type {any[]}
- */
-const log = [];
-
 export default test({
 	compileOptions: {
 		dev: true
@@ -18,27 +11,10 @@ export default test({
 
 	mode: ['hydrate'],
 
-	before_test() {
-		console.error = (x) => {
-			log.push(x);
-		};
-	},
-
-	after_test() {
-		console.error = console_error;
-		log.length = 0;
-	},
-
-	async test({ assert }) {
-		assert.equal(
-			log[0].split('\n')[0],
-			'node_invalid_placement_ssr: `<p>` (main.svelte:6:0) cannot contain `<h1>` (h1.svelte:1:0)'
-		);
-		assert.equal(
-			log[1].split('\n')[0],
-			'node_invalid_placement_ssr: `<form>` (main.svelte:9:0) cannot contain `<form>` (form.svelte:1:0)'
-		);
-	},
+	errors: [
+		'node_invalid_placement_ssr: `<p>` (main.svelte:6:0) cannot contain `<h1>` (h1.svelte:1:0)\n\nThis can cause content to shift around as the browser repairs the HTML, and will likely result in a `hydration_mismatch` warning.',
+		'node_invalid_placement_ssr: `<form>` (main.svelte:9:0) cannot contain `<form>` (form.svelte:1:0)\n\nThis can cause content to shift around as the browser repairs the HTML, and will likely result in a `hydration_mismatch` warning.'
+	],
 
 	warnings: [
 		'Hydration failed because the initial UI does not match what was rendered on the server'