1 files changed, 29 insertions, 0 deletions
diff --git a/packages/webapi/test/internals.js b/packages/webapi/test/internals.js
new file mode 100644
index 000000000..84f918fb6
--- /dev/null
+++ b/packages/webapi/test/internals.js
@@ -0,0 +1,29 @@
+import { assert, test } from '../run/test.setup.js'
+import { polyfill } from '../mod.js'
+
+test(() => {
+	return [
+		{
+			name: 'Includes polyfill.internals functionality',
+			test() {
+				const target = {}
+	
+				polyfill(target, { exclude: 'window document' })
+
+				const pseudo = { ...target }
+
+				assert.equal(Reflect.has(pseudo, 'document'), false)
+
+				const CustomElement = class extends pseudo.HTMLElement {}
+
+				pseudo.customElements.define('custom-element', CustomElement)
+
+				polyfill.internals(pseudo, 'Document')
+
+				assert.equal(Reflect.has(pseudo, 'document'), true)
+
+				assert.equal(CustomElement.prototype.isPrototypeOf(pseudo.document.createElement('custom-element')), true)
+			},
+		}
+	]
+})