node fixtures: Improve realm_user__add.

We also improve the relevant dispatch test a bit.

frontend_tests/node_tests/dispatch.js

@@ -491,9 +491,16 @@ run_test("realm_domains", (override) => {
 
 run_test("realm_user", (override) => {
     let event = event_fixtures.realm_user__add;
-    dispatch(event);
+    dispatch({...event});
     const added_person = people.get_by_user_id(event.person.user_id);
+    // sanity check a few individual fields
     assert.equal(added_person.full_name, "Test User");
+    assert.equal(added_person.timezone, "US/Eastern");
+
+    // ...but really the whole struct gets copied without any
+    // manipulation
+    assert.deepEqual(added_person, event.person);
+
     assert(people.is_active_user_for_popover(event.person.user_id));
 
     event = event_fixtures.realm_user__remove;

frontend_tests/node_tests/lib/events.js

@@ -428,7 +428,19 @@ exports.fixtures = {
     realm_user__add: {
         type: "realm_user",
         op: "add",
-        person: exports.test_user,
+        person: {
+            ...exports.test_user,
+            avatar_url: "/some/path/to/avatar",
+            avatar_version: 1,
+            is_admin: false,
+            is_active: true,
+            is_owner: false,
+            is_bot: false,
+            is_guest: false,
+            profile_data: {},
+            timezone: "US/Eastern",
+            date_joined: "2020-01-01",
+        },
     },
 
     realm_user__remove: {