feat(labs/ssr): Prevent exposure of window object on globalThis

.changeset/loud-radios-change.md

@@ -0,0 +1,5 @@
+---
+'@lit-labs/ssr': major
+---
+
+dom shim does not expose the window object

packages/labs/ssr/src/lib/dom-shim.ts

@@ -159,8 +159,6 @@ export const getWindow = ({
     ...props,
   };
 
-  window.window = window;
-
   if (includeJSBuiltIns) {
     Object.assign(window, {
       // No-op any async tasks
@@ -204,8 +202,5 @@ export const installWindowOnGlobal = (props: {[key: string]: unknown} = {}) => {
     const window = getWindow({props});
     // Copy initial window globals to node global
     Object.assign(globalThis, window);
-    // Set up global reference to window so all globals added to window are
-    // added to the node global
-    globalThis.window = globalThis as typeof globalThis & Window;
   }
 };

packages/labs/ssr/src/test/integration/server/server.ts

@@ -31,8 +31,10 @@ export const ssrMiddleware = () => {
       module = await import(`../tests/${testFile}-ssr.js`);
     } else {
       // mode === 'vm'
+      const window = getWindow({includeJSBuiltIns: true});
+      window.window = window;
       const loader = new ModuleLoader({
-        global: getWindow({includeJSBuiltIns: true}),
+        global: window,
       });
       module = (
         await loader.importModule(

packages/labs/ssr/src/test/lib/dom-shim_test.ts

@@ -4,31 +4,44 @@
  * SPDX-License-Identifier: BSD-3-Clause
  */
 
-import {getWindow} from '../../lib/dom-shim.js';
+import {installWindowOnGlobal, getWindow} from '../../lib/dom-shim.js';
 import {test} from 'uvu';
 // eslint-disable-next-line import/extensions
 import * as assert from 'uvu/assert';
 
-const window = getWindow({}) as unknown as Window;
-const {HTMLElement} = window.window;
+function testWithHtmlElement(HTMLElement: any) {
+  test('elements without an attached shadow root should expose a null value from the "shadowRoot" property', () => {
+    class UnattachedShadowRoot extends HTMLElement {}
+    const element = new UnattachedShadowRoot();
+    assert.is(element.shadowRoot, null);
+  });
+  test('elements defined with an open shadow root should expose it\'s shadow root from the "shadowRoot" property', () => {
+    class OpenShadowRoot extends HTMLElement {}
+    const element = new OpenShadowRoot();
+    const shadow = element.attachShadow({mode: 'open'});
+    assert.is(shadow, element.shadowRoot);
+    assert.is(shadow.host, element);
+  });
+  test('elements defined with a closed shadow root should expose a null value from the "shadowRoot" property', () => {
+    class ClosedShadowRoot extends HTMLElement {}
+    const element = new ClosedShadowRoot();
+    element.attachShadow({mode: 'closed'});
+    assert.is(element.shadowRoot, null);
+  });
 
-test('elements without an attached shadow root should expose a null value from the "shadowRoot" property', () => {
-  class UnattachedShadowRoot extends HTMLElement {}
-  const element = new UnattachedShadowRoot();
-  assert.is(element.shadowRoot, null);
-});
-test('elements defined with an open shadow root should expose it\'s shadow root from the "shadowRoot" property', () => {
-  class OpenShadowRoot extends HTMLElement {}
-  const element = new OpenShadowRoot();
-  const shadow = element.attachShadow({mode: 'open'});
-  assert.is(shadow, element.shadowRoot);
-  assert.is(shadow.host, element);
-});
-test('elements defined with a closed shadow root should expose a null value from the "shadowRoot" property', () => {
-  class ClosedShadowRoot extends HTMLElement {}
-  const element = new ClosedShadowRoot();
-  element.attachShadow({mode: 'closed'});
-  assert.is(element.shadowRoot, null);
-});
+  test.run();
+}
 
-test.run();
+function testWithGlobalShim() {
+  installWindowOnGlobal({});
+  const {HTMLElement} = globalThis;
+  testWithHtmlElement(HTMLElement);
+}
+function testWithWindow() {
+  const window = getWindow({});
+  const {HTMLElement} = window;
+  testWithHtmlElement(HTMLElement);
+}
+
+testWithWindow();
+testWithGlobalShim();

packages/labs/ssr/src/test/lib/render-lit_test.ts

@@ -14,11 +14,13 @@ import {RenderInfo} from '../../index.js';
 
 import type * as testModule from '../test-files/render-test-module.js';
 
+const window = getWindow({
+  includeJSBuiltIns: true,
+  props: {require: createRequire(import.meta.url)},
+});
+window.window = window;
 const loader = new ModuleLoader({
-  global: getWindow({
-    includeJSBuiltIns: true,
-    props: {require: createRequire(import.meta.url)},
-  }),
+  global: window,
 });
 
 /**