Use browser default time and number formatting with polyfills if needed (#9481)

Co-authored-by: Paulus Schoutsen <balloob@gmail.com>

test/common/entity/get_group_entities.spec.ts

@@ -0,0 +1,39 @@
+import { assert } from "chai";
+
+import { getGroupEntities } from "../../../src/common/entity/get_group_entities";
+
+import { createEntities, createGroup, entityMap } from "./test_util";
+
+describe("getGroupEntities", () => {
+  it("works if all entities exist", () => {
+    const entities = createEntities(5);
+    const entityIds = Object.keys(entities);
+
+    const group = createGroup({
+      attributes: { entity_id: entityIds.splice(0, 2) },
+    });
+
+    const groupEntities = entityMap(
+      group.attributes.entity_id.map((ent) => entities[ent])
+    );
+    assert.deepEqual(groupEntities, getGroupEntities(entities, group));
+  });
+
+  it("works if one entity doesn't exist", () => {
+    const entities = createEntities(5);
+    const entityIds = Object.keys(entities);
+
+    const groupEntities = entityMap([
+      entities[entityIds[0]],
+      entities[entityIds[1]],
+    ]);
+
+    const group = createGroup({
+      attributes: {
+        entity_id: entityIds.splice(0, 2).concat("light.does_not_exist"),
+      },
+    });
+
+    assert.deepEqual(groupEntities, getGroupEntities(entities, group));
+  });
+});