diff --git a/web/tests/compose_validate.test.js b/web/tests/compose_validate.test.js
index 1561870e85..d8d9617f1a 100644
--- a/web/tests/compose_validate.test.js
+++ b/web/tests/compose_validate.test.js
@@ -337,19 +337,28 @@ test_ui("test_stream_wildcard_mention_allowed", ({override, override_rewire}) =>
     // policy matters.
     override_rewire(peer_data, "get_subscriber_count", () => 16);
 
-    realm.realm_wildcard_mention_policy =
-        settings_config.wildcard_mention_policy_values.by_everyone.code;
+    override(
+        realm,
+        "realm_wildcard_mention_policy",
+        settings_config.wildcard_mention_policy_values.by_everyone.code,
+    );
     override(current_user, "is_guest", true);
     override(current_user, "is_admin", false);
     assert.ok(compose_validate.stream_wildcard_mention_allowed());
 
-    realm.realm_wildcard_mention_policy =
-        settings_config.wildcard_mention_policy_values.nobody.code;
+    override(
+        realm,
+        "realm_wildcard_mention_policy",
+        settings_config.wildcard_mention_policy_values.nobody.code,
+    );
     override(current_user, "is_admin", true);
     assert.ok(!compose_validate.stream_wildcard_mention_allowed());
 
-    realm.realm_wildcard_mention_policy =
-        settings_config.wildcard_mention_policy_values.by_members.code;
+    override(
+        realm,
+        "realm_wildcard_mention_policy",
+        settings_config.wildcard_mention_policy_values.by_members.code,
+    );
     override(current_user, "is_guest", true);
     override(current_user, "is_admin", false);
     assert.ok(!compose_validate.stream_wildcard_mention_allowed());
@@ -357,16 +366,22 @@ test_ui("test_stream_wildcard_mention_allowed", ({override, override_rewire}) =>
     override(current_user, "is_guest", false);
     assert.ok(compose_validate.stream_wildcard_mention_allowed());
 
-    realm.realm_wildcard_mention_policy =
-        settings_config.wildcard_mention_policy_values.by_moderators_only.code;
+    override(
+        realm,
+        "realm_wildcard_mention_policy",
+        settings_config.wildcard_mention_policy_values.by_moderators_only.code,
+    );
     override(current_user, "is_moderator", false);
     assert.ok(!compose_validate.stream_wildcard_mention_allowed());
 
     override(current_user, "is_moderator", true);
     assert.ok(compose_validate.stream_wildcard_mention_allowed());
 
-    realm.realm_wildcard_mention_policy =
-        settings_config.wildcard_mention_policy_values.by_admins_only.code;
+    override(
+        realm,
+        "realm_wildcard_mention_policy",
+        settings_config.wildcard_mention_policy_values.by_admins_only.code,
+    );
     override(current_user, "is_admin", false);
     assert.ok(!compose_validate.stream_wildcard_mention_allowed());
 
@@ -375,8 +390,11 @@ test_ui("test_stream_wildcard_mention_allowed", ({override, override_rewire}) =>
     override(current_user, "is_admin", true);
     assert.ok(compose_validate.stream_wildcard_mention_allowed());
 
-    realm.realm_wildcard_mention_policy =
-        settings_config.wildcard_mention_policy_values.by_full_members.code;
+    override(
+        realm,
+        "realm_wildcard_mention_policy",
+        settings_config.wildcard_mention_policy_values.by_full_members.code,
+    );
     const person = people.get_by_user_id(current_user.user_id);
     person.date_joined = new Date(Date.now());
     override(realm, "realm_waiting_period_threshold", 10);
@@ -388,8 +406,11 @@ test_ui("test_stream_wildcard_mention_allowed", ({override, override_rewire}) =>
     // Now, check for small streams (<=15 subscribers) where the wildcard mention
     // policy doesn't matter; everyone is allowed to use wildcard mentions.
     override_rewire(peer_data, "get_subscriber_count", () => 14);
-    realm.realm_wildcard_mention_policy =
-        settings_config.wildcard_mention_policy_values.by_admins_only.code;
+    override(
+        realm,
+        "realm_wildcard_mention_policy",
+        settings_config.wildcard_mention_policy_values.by_admins_only.code,
+    );
     override(current_user, "is_admin", false);
     override(current_user, "is_guest", true);
     assert.ok(compose_validate.stream_wildcard_mention_allowed());
diff --git a/web/tests/composebox_typeahead.test.js b/web/tests/composebox_typeahead.test.js
index dad4de0130..4dc769df48 100644
--- a/web/tests/composebox_typeahead.test.js
+++ b/web/tests/composebox_typeahead.test.js
@@ -888,9 +888,9 @@ test("initialize", ({override, override_rewire, mock_template}) => {
     });
 
     let expected_value;
-    realm.custom_profile_field_types = {
+    override(realm, "custom_profile_field_types", {
         PRONOUNS: {id: 8, name: "Pronouns"},
-    };
+    });
 
     mock_template("typeahead_list_item.hbs", true, (data, html) => {
         assert.equal(typeof data.primary, "string");
diff --git a/web/tests/dispatch.test.js b/web/tests/dispatch.test.js
index e2bab7367d..654e142894 100644
--- a/web/tests/dispatch.test.js
+++ b/web/tests/dispatch.test.js
@@ -474,7 +474,7 @@ run_test("realm settings", ({override}) => {
 
     // realm
     function test_realm_boolean(event, parameter_name) {
-        realm[parameter_name] = true;
+        override(realm, parameter_name, true);
         event = {...event};
         event.value = false;
         dispatch(event);
@@ -486,7 +486,7 @@ run_test("realm settings", ({override}) => {
     }
 
     function test_realm_integer(event, parameter_name) {
-        realm[parameter_name] = 1;
+        override(realm, parameter_name, 1);
         event = {...event};
         event.value = 2;
         dispatch(event);
diff --git a/web/tests/people.test.js b/web/tests/people.test.js
index 62fdf94fb2..e7e5d69bbb 100644
--- a/web/tests/people.test.js
+++ b/web/tests/people.test.js
@@ -576,10 +576,10 @@ test_people("my_custom_profile_data", () => {
     assert.equal(people.my_custom_profile_data(4), "My phone number");
 });
 
-test_people("get_custom_fields_by_type", () => {
+test_people("get_custom_fields_by_type", ({override}) => {
     people.add_active_user(stewie);
     const person = people.get_by_user_id(stewie.user_id);
-    realm.custom_profile_field_types = {
+    override(realm, "custom_profile_field_types", {
         SHORT_TEXT: {
             id: 1,
             name: "Short text",
@@ -588,8 +588,8 @@ test_people("get_custom_fields_by_type", () => {
             id: 8,
             name: "Pronouns",
         },
-    };
-    realm.custom_profile_fields = [
+    });
+    override(realm, "custom_profile_fields", [
         {
             id: 1,
             name: "Phone number (mobile)",
@@ -605,7 +605,7 @@ test_people("get_custom_fields_by_type", () => {
             name: "Pronouns",
             type: 8,
         },
-    ];
+    ]);
     const SHORT_TEXT_ID = 1;
     assert.deepEqual(people.get_custom_fields_by_type(person.user_id, SHORT_TEXT_ID), [
         "(888) 888-8888",
diff --git a/web/tests/settings_bots.test.js b/web/tests/settings_bots.test.js
index dca6581c6c..5b77486f8e 100644
--- a/web/tests/settings_bots.test.js
+++ b/web/tests/settings_bots.test.js
@@ -40,11 +40,11 @@ bot_data.initialize(bot_data_params);
 function test(label, f) {
     run_test(label, ({override}) => {
         override(realm, "realm_url", "https://chat.example.com");
-        realm.realm_embedded_bots = [
+        override(realm, "realm_embedded_bots", [
             {name: "converter", config: {}},
             {name: "giphy", config: {key: "12345678"}},
             {name: "foobot", config: {bar: "baz", qux: "quux"}},
-        ];
+        ]);
 
         f({override});
     });
diff --git a/web/tests/settings_data.test.js b/web/tests/settings_data.test.js
index a0a0a00a24..4389dd8305 100644
--- a/web/tests/settings_data.test.js
+++ b/web/tests/settings_data.test.js
@@ -112,34 +112,34 @@ run_test("user_can_change_logo", ({override}) => {
 function test_policy(label, policy, validation_func) {
     run_test(label, ({override}) => {
         override(current_user, "is_admin", true);
-        realm[policy] = settings_config.common_policy_values.by_admins_only.code;
+        override(realm, policy, settings_config.common_policy_values.by_admins_only.code);
         assert.equal(validation_func(), true);
 
         override(current_user, "is_admin", false);
         assert.equal(validation_func(), false);
 
         override(current_user, "is_moderator", true);
-        realm[policy] = settings_config.common_policy_values.by_moderators_only.code;
+        override(realm, policy, settings_config.common_policy_values.by_moderators_only.code);
         assert.equal(validation_func(), true);
 
         override(current_user, "is_moderator", false);
         assert.equal(validation_func(), false);
 
         override(current_user, "is_guest", true);
-        realm[policy] = settings_config.common_policy_values.by_members.code;
+        override(realm, policy, settings_config.common_policy_values.by_members.code);
         assert.equal(validation_func(), false);
 
         override(current_user, "is_guest", false);
         assert.equal(validation_func(), true);
 
         page_params.is_spectator = true;
-        realm[policy] = settings_config.common_policy_values.by_members.code;
+        override(realm, policy, settings_config.common_policy_values.by_members.code);
         assert.equal(validation_func(), false);
 
         page_params.is_spectator = false;
         assert.equal(validation_func(), true);
 
-        realm[policy] = settings_config.common_policy_values.by_full_members.code;
+        override(realm, policy, settings_config.common_policy_values.by_full_members.code);
         override(current_user, "user_id", 30);
         isaac.date_joined = new Date(Date.now());
         settings_data.initialize(isaac.date_joined);
@@ -176,30 +176,34 @@ test_policy(
 function test_message_policy(label, policy, validation_func) {
     run_test(label, ({override}) => {
         override(current_user, "is_admin", true);
-        realm[policy] = settings_config.common_message_policy_values.by_admins_only.code;
+        override(realm, policy, settings_config.common_message_policy_values.by_admins_only.code);
         assert.equal(validation_func(), true);
 
         override(current_user, "is_admin", false);
         override(current_user, "is_moderator", true);
         assert.equal(validation_func(), false);
 
-        realm[policy] = settings_config.common_message_policy_values.by_moderators_only.code;
+        override(
+            realm,
+            policy,
+            settings_config.common_message_policy_values.by_moderators_only.code,
+        );
         assert.equal(validation_func(), true);
 
         override(current_user, "is_moderator", false);
         assert.equal(validation_func(), false);
 
         override(current_user, "is_guest", true);
-        realm[policy] = settings_config.common_message_policy_values.by_everyone.code;
+        override(realm, policy, settings_config.common_message_policy_values.by_everyone.code);
         assert.equal(validation_func(), true);
 
-        realm[policy] = settings_config.common_message_policy_values.by_members.code;
+        override(realm, policy, settings_config.common_message_policy_values.by_members.code);
         assert.equal(validation_func(), false);
 
         override(current_user, "is_guest", false);
         assert.equal(validation_func(), true);
 
-        realm[policy] = settings_config.common_message_policy_values.by_full_members.code;
+        override(realm, policy, settings_config.common_message_policy_values.by_full_members.code);
         override(current_user, "user_id", 30);
         isaac.date_joined = new Date(Date.now());
         override(realm, "realm_waiting_period_threshold", 10);
@@ -232,8 +236,11 @@ run_test("user_can_move_messages_to_another_topic_nobody_case", ({override}) =>
 run_test("user_can_move_messages_between_streams_nobody_case", ({override}) => {
     override(current_user, "is_admin", true);
     override(current_user, "is_guest", false);
-    realm.realm_move_messages_between_streams_policy =
-        settings_config.move_messages_between_streams_policy_values.nobody.code;
+    override(
+        realm,
+        "realm_move_messages_between_streams_policy",
+        settings_config.move_messages_between_streams_policy_values.nobody.code,
+    );
     assert.equal(settings_data.user_can_move_messages_between_streams(), false);
 });
 
@@ -272,8 +279,11 @@ run_test("using_dark_theme", ({override}) => {
 run_test("user_can_invite_others_to_realm_nobody_case", ({override}) => {
     override(current_user, "is_admin", true);
     override(current_user, "is_guest", false);
-    realm.realm_invite_to_realm_policy =
-        settings_config.email_invite_to_realm_policy_values.nobody.code;
+    override(
+        realm,
+        "realm_invite_to_realm_policy",
+        settings_config.email_invite_to_realm_policy_values.nobody.code,
+    );
     assert.equal(settings_data.user_can_invite_users_by_email(), false);
 });
 
@@ -322,14 +332,14 @@ function test_realm_group_settings(setting_name, validation_func) {
 
         page_params.is_spectator = false;
         override(current_user, "is_guest", false);
-        realm[setting_name] = 1;
+        override(realm, setting_name, 1);
         override(current_user, "user_id", admin_user_id);
         assert.equal(validation_func(), true);
 
         override(current_user, "user_id", moderator_user_id);
         assert.equal(validation_func(), false);
 
-        realm[setting_name] = 2;
+        override(realm, setting_name, 2);
         override(current_user, "user_id", moderator_user_id);
         assert.equal(validation_func(), true);
 
diff --git a/web/tests/settings_org.test.js b/web/tests/settings_org.test.js
index 328903eb63..6402a3d71e 100644
--- a/web/tests/settings_org.test.js
+++ b/web/tests/settings_org.test.js
@@ -3,7 +3,7 @@
 const assert = require("node:assert/strict");
 
 const {$t} = require("./lib/i18n");
-const {mock_esm, zrequire, set_global} = require("./lib/namespace");
+const {mock_esm, set_global, zrequire} = require("./lib/namespace");
 const {run_test, noop} = require("./lib/test");
 const blueslip = require("./lib/zblueslip");
 const $ = require("./lib/zjquery");
@@ -38,10 +38,10 @@ function test(label, f) {
     run_test(label, (helpers) => {
         $("#realm-icon-upload-widget .upload-spinner-background").css = noop;
         helpers.override(current_user, "is_admin", false);
-        realm.realm_domains = [
+        helpers.override(realm, "realm_domains", [
             {domain: "example.com", allow_subdomains: true},
             {domain: "example.org", allow_subdomains: false},
-        ];
+        ]);
         helpers.override(realm, "realm_authentication_methods", {});
         settings_org.reset();
         f(helpers);
@@ -320,11 +320,15 @@ function test_sync_realm_settings({override}) {
         in the following order - by_admins_only, by_moderators_only, by_full_members,
         by_members. */
 
-        realm[`realm_${property_name}`] = settings_config.common_policy_values.by_members.code;
+        override(
+            realm,
+            `realm_${property_name}`,
+            settings_config.common_policy_values.by_members.code,
+        );
         $property_elem.val(settings_config.common_policy_values.by_members.code);
 
         for (const policy_value of Object.values(settings_config.common_policy_values)) {
-            realm[`realm_${property_name}`] = policy_value.code;
+            override(realm, `realm_${property_name}`, policy_value.code);
             settings_org.sync_realm_settings(property_name);
             assert.equal($property_elem.val(), policy_value.code);
         }
@@ -409,12 +413,15 @@ function test_sync_realm_settings({override}) {
     }
 }
 
-function test_parse_time_limit() {
+function test_parse_time_limit({override}) {
     const $elem = $("#id_realm_message_content_edit_limit_minutes");
     const test_function = (value, expected_value = value) => {
         $elem.val(value);
-        realm.realm_message_content_edit_limit_seconds =
-            settings_components.parse_time_limit($elem);
+        override(
+            realm,
+            "realm_message_content_edit_limit_seconds",
+            settings_components.parse_time_limit($elem),
+        );
         assert.equal(
             settings_components.get_realm_time_limits_in_minutes(
                 "realm_message_content_edit_limit_seconds",
@@ -516,7 +523,7 @@ function test_discard_changes_button({override}, discard_changes) {
 
 test("set_up", ({override, override_rewire}) => {
     override_rewire(settings_org, "check_disable_message_delete_limit_setting_dropdown", noop);
-    realm.realm_available_video_chat_providers = {
+    override(realm, "realm_available_video_chat_providers", {
         jitsi_meet: {
             id: 1,
             name: "Jitsi Meet",
@@ -529,7 +536,7 @@ test("set_up", ({override, override_rewire}) => {
             id: 4,
             name: "BigBlueButton",
         },
-    };
+    });
 
     let upload_realm_logo_or_icon;
     realm_icon.build_realm_icon_widget = (f) => {
@@ -679,7 +686,7 @@ test("set_up", ({override, override_rewire}) => {
     test_extract_property_name();
     test_change_save_button_state();
     test_sync_realm_settings({override});
-    test_parse_time_limit();
+    test_parse_time_limit({override});
     test_discard_changes_button(
         {override},
         $(".admin-realm-form").get_on_handler(
diff --git a/web/tests/typeahead_helper.test.js b/web/tests/typeahead_helper.test.js
index 1260749b5f..72c6a5556d 100644
--- a/web/tests/typeahead_helper.test.js
+++ b/web/tests/typeahead_helper.test.js
@@ -826,11 +826,11 @@ test("highlight_with_escaping", () => {
     assert.equal(result, expected);
 });
 
-test("render_person when emails hidden", ({mock_template}) => {
+test("render_person when emails hidden", ({mock_template, override}) => {
     // Test render_person with regular person, under hidden email visibility case
-    realm.custom_profile_field_types = {
+    override(realm, "custom_profile_field_types", {
         PRONOUNS: {id: 8, name: "Pronouns"},
-    };
+    });
     let rendered = false;
     mock_template("typeahead_list_item.hbs", false, (args) => {
         assert.equal(args.primary, b_user_1.full_name);
@@ -842,12 +842,12 @@ test("render_person when emails hidden", ({mock_template}) => {
     assert.ok(rendered);
 });
 
-test("render_person", ({mock_template}) => {
+test("render_person", ({mock_template, override}) => {
     // Test render_person with regular person
     a_user.delivery_email = "a_user_delivery@zulip.org";
-    realm.custom_profile_field_types = {
+    override(realm, "custom_profile_field_types", {
         PRONOUNS: {id: 8, name: "Pronouns"},
-    };
+    });
     let rendered = false;
     mock_template("typeahead_list_item.hbs", false, (args) => {
         assert.equal(args.primary, a_user.full_name);
diff --git a/web/tests/user_groups.test.js b/web/tests/user_groups.test.js
index 728df4bd19..033fef2c42 100644
--- a/web/tests/user_groups.test.js
+++ b/web/tests/user_groups.test.js
@@ -370,7 +370,7 @@ run_test("is_user_in_group", () => {
     assert.equal(user_groups.is_user_in_group(admins.id, 6), false);
 });
 
-run_test("get_realm_user_groups_for_dropdown_list_widget", () => {
+run_test("get_realm_user_groups_for_dropdown_list_widget", ({override}) => {
     const nobody = {
         name: "role:nobody",
         description: "foo",
@@ -443,7 +443,7 @@ run_test("get_realm_user_groups_for_dropdown_list_widget", () => {
         direct_subgroup_ids: new Set([4, 5]),
     };
 
-    realm.server_supported_permission_settings = {
+    override(realm, "server_supported_permission_settings", {
         stream: {
             can_remove_subscribers_group: {
                 require_system_group: true,
@@ -478,7 +478,7 @@ run_test("get_realm_user_groups_for_dropdown_list_widget", () => {
                 allowed_system_groups: ["role:everyone", "role:members"],
             },
         },
-    };
+    });
 
     let expected_groups_list = [
         {name: "translated: Admins, moderators, members and guests", unique_id: 6},