node_tests: Enforce 100% coverage for test files.

This makes it easier to find obsolete parts of the tests that should
be cleaned up.

Signed-off-by: Anders Kaseorg <anders@zulip.com>

frontend_tests/node_tests/activity.js

@@ -381,36 +381,40 @@ test("first/prev/next", ({override, mock_template}) => {
     let rendered_fred;
 
     mock_template("user_presence_row.hbs", false, (data) => {
-        if (data.user_id === alice.user_id) {
+        switch (data.user_id) {
-            rendered_alice = true;
+            case alice.user_id:
-            assert.deepEqual(data, {
+                rendered_alice = true;
-                faded: true,
+                assert.deepEqual(data, {
-                href: "#narrow/pm-with/1-alice",
+                    faded: true,
-                is_current_user: false,
+                    href: "#narrow/pm-with/1-alice",
-                my_user_status: undefined,
+                    is_current_user: false,
-                name: "Alice Smith",
+                    my_user_status: undefined,
-                num_unread: 0,
+                    name: "Alice Smith",
-                user_circle_class: "user_circle_green",
+                    num_unread: 0,
-                user_circle_status: "translated: Active",
+                    user_circle_class: "user_circle_green",
-                user_id: alice.user_id,
+                    user_circle_status: "translated: Active",
-                status_emoji_info: undefined,
+                    user_id: alice.user_id,
-            });
+                    status_emoji_info: undefined,
-        } else if (data.user_id === fred.user_id) {
+                });
-            rendered_fred = true;
+                break;
-            assert.deepEqual(data, {
+            case fred.user_id:
-                href: "#narrow/pm-with/2-fred",
+                rendered_fred = true;
-                name: "Fred Flintstone",
+                assert.deepEqual(data, {
-                user_id: fred.user_id,
+                    href: "#narrow/pm-with/2-fred",
-                my_user_status: undefined,
+                    name: "Fred Flintstone",
-                is_current_user: false,
+                    user_id: fred.user_id,
-                num_unread: 0,
+                    my_user_status: undefined,
-                user_circle_class: "user_circle_green",
+                    is_current_user: false,
-                user_circle_status: "translated: Active",
+                    num_unread: 0,
-                faded: false,
+                    user_circle_class: "user_circle_green",
-                status_emoji_info: undefined,
+                    user_circle_status: "translated: Active",
-            });
+                    faded: false,
-        } else {
+                    status_emoji_info: undefined,
-            throw new Error(`we did not expect to have to render a row for  ${data.name}`);
+                });
+                break;
+            /* istanbul ignore next */
+            default:
+                throw new Error(`we did not expect to have to render a row for  ${data.name}`);
         }
     });
 
@@ -555,13 +559,8 @@ test("realm_presence_disabled", () => {
 
 test("redraw_muted_user", () => {
     muted_users.add_muted_user(mark.user_id);
-    let appended_html;
-    $("#user_presences").append = function (html) {
-        appended_html = html;
-    };
-
     activity.redraw_user(mark.user_id);
-    assert.equal(appended_html, undefined);
+    assert.equal($("#user_presences").html(), "never-been-set");
 });
 
 test("update_presence_info", ({override, override_rewire}) => {

frontend_tests/node_tests/billing.js

@@ -136,14 +136,12 @@ run_test("licensechange", ({override, override_rewire}) => {
     assert.ok(confirm_license_modal_shown);
 
     override(helpers, "is_valid_input", () => false);
-    let prevent_default_called = false;
     const event = {
-        prevent_default: () => {
+        preventDefault: /* istanbul ignore next */ () => {
-            prevent_default_called = true;
+            throw new Error("unexpected preventDefault call");
         },
     };
     update_licenses_button_click_handler(event);
-    assert.ok(!prevent_default_called);
 
     const update_next_renewal_licenses_button_click_handler = $(
         "#update-licenses-at-next-renewal-button",

frontend_tests/node_tests/channel.js

@@ -399,19 +399,18 @@ test("while_reloading", () => {
 
     assert.equal(channel.get({ignore_reload: false}), undefined);
 
-    let orig_success_called = false;
-    let orig_error_called = false;
-
     test_with_mock_ajax({
         run_code() {
             channel.del({
                 url: "/json/endpoint",
                 ignore_reload: true,
+                /* istanbul ignore next */
                 success() {
-                    orig_success_called = true;
+                    throw new Error("unexpected success");
                 },
+                /* istanbul ignore next */
                 error() {
-                    orig_error_called = true;
+                    throw new Error("unexpected error");
                 },
             });
         },
@@ -419,11 +418,9 @@ test("while_reloading", () => {
         check_ajax_options(options) {
             blueslip.expect("log", "Ignoring DELETE /json/endpoint response while reloading");
             options.simulate_success();
-            assert.ok(!orig_success_called);
 
             blueslip.expect("log", "Ignoring DELETE /json/endpoint error response while reloading");
             options.simulate_error();
-            assert.ok(!orig_error_called);
         },
     });
 });

frontend_tests/node_tests/components.js

@@ -106,6 +106,7 @@ function make_switcher() {
         switch (sel) {
             case ".ind-tab":
                 return ind_tab;
+            /* istanbul ignore next */
             default:
                 throw new Error("unknown selector: " + sel);
         }
@@ -151,6 +152,7 @@ mock_jquery((sel, attributes) => {
             );
             return make_tab(tab_id);
         }
+        /* istanbul ignore next */
         default:
             throw new Error("unknown selector: " + sel);
     }

frontend_tests/node_tests/compose.js

@@ -145,10 +145,6 @@ test_ui("send_message", ({override, override_rewire}) => {
         return stub_state;
     }
 
-    set_global("setTimeout", (func) => {
-        func();
-    });
-
     override(server_events, "assert_get_events_running", () => {
         stub_state.get_events_running_called += 1;
     });
@@ -635,13 +631,15 @@ test_ui("on_events", ({override, override_rewire}) => {
         );
 
         helper.$container.data = (field) => {
-            if (field === "user-id") {
+            switch (field) {
-                return "34";
+                case "user-id":
+                    return "34";
+                case "stream-id":
+                    return "102";
+                /* istanbul ignore next */
+                default:
+                    throw new Error(`Unknown field ${field}`);
             }
-            if (field === "stream-id") {
-                return "102";
-            }
-            throw new Error(`Unknown field ${field}`);
         };
         helper.$target.prop("disabled", false);
 
@@ -737,9 +735,6 @@ test_ui("on_events", ({override, override_rewire}) => {
 
     (function test_attach_files_compose_clicked() {
         const handler = $("#compose").get_on_handler("click", ".compose_upload_file");
-        $("#compose .file_input").clone = (param) => {
-            assert.ok(param);
-        };
         let compose_file_input_clicked = false;
         $("#compose .file_input").on("click", () => {
             compose_file_input_clicked = true;

frontend_tests/node_tests/compose_actions.js

@@ -390,6 +390,7 @@ test("quote_and_reply", ({override, override_rewire}) => {
         raw_content: "Testing.",
     };
 
+    /* istanbul ignore next */
     function whiny_get() {
         assert.fail("channel.get should not be used if raw_content is present");
     }

frontend_tests/node_tests/compose_fade.js

@@ -19,6 +19,7 @@ mock_jquery((selector) => {
                     return "lunch";
                 },
             };
+        /* istanbul ignore next */
         default:
             throw new Error(`Unknown selector ${selector}`);
     }

frontend_tests/node_tests/compose_pm_pill.js

@@ -41,8 +41,6 @@ run_test("pills", ({override}) => {
     people.add_active_user(iago);
     people.add_active_user(hamlet);
 
-    people.get_realm_users = () => [iago, othello, hamlet];
-
     const $recipient_stub = $("#private_message_recipient");
     const pill_container_stub = "pill-container";
     $recipient_stub.set_parent(pill_container_stub);
@@ -81,25 +79,29 @@ run_test("pills", ({override}) => {
     let get_by_email_called = false;
     people.get_by_email = (user_email) => {
         get_by_email_called = true;
-        if (user_email === iago.email) {
+        switch (user_email) {
-            return iago;
+            case iago.email:
+                return iago;
+            case othello.email:
+                return othello;
+            /* istanbul ignore next */
+            default:
+                throw new Error(`Unknown user email ${user_email}`);
         }
-        if (user_email === othello.email) {
-            return othello;
-        }
-        throw new Error(`Unknown user email ${user_email}`);
     };
 
     let get_by_user_id_called = false;
     people.get_by_user_id = (id) => {
         get_by_user_id_called = true;
-        if (id === othello.user_id) {
+        switch (id) {
-            return othello;
+            case othello.user_id:
+                return othello;
+            case hamlet.user_id:
+                return hamlet;
+            /* istanbul ignore next */
+            default:
+                throw new Error(`Unknown user ID ${id}`);
         }
-        if (id === hamlet.user_id) {
-            return hamlet;
-        }
-        throw new Error(`Unknown user ID ${id}`);
     };
 
     function test_create_item(handler) {

frontend_tests/node_tests/compose_ui.js

@@ -71,6 +71,7 @@ function make_textbox(s) {
     };
 
     $widget.val = function (new_val) {
+        /* istanbul ignore if */
         if (new_val) {
             $widget.s = new_val;
             return this;
@@ -301,6 +302,7 @@ run_test("quote_and_reply", ({override, override_rewire}) => {
             textarea_caret_pos = arg;
             return this;
         }
+        /* istanbul ignore if */
         if (typeof arg !== "string") {
             console.info(arg);
             throw new Error("We expected the actual code to pass in a string.");

frontend_tests/node_tests/compose_validate.js

@@ -163,12 +163,10 @@ test_ui("validate", ({override, mock_template}) => {
 
     add_content_to_compose_box();
     let zephyr_checked = false;
-    $("#zephyr-mirror-error").is = () => {
+    $("#zephyr-mirror-error").is = (arg) => {
-        if (!zephyr_checked) {
+        assert.equal(arg, ":visible");
-            zephyr_checked = true;
+        zephyr_checked = true;
-            return true;
+        return true;
-        }
-        return false;
     };
     assert.ok(!compose_validate.validate());
     assert.ok(zephyr_checked);
@@ -740,14 +738,17 @@ test_ui("warn_if_mentioning_unsubscribed_user", ({override, override_rewire, moc
 
     let looked_for_existing;
     $warning_row.data = (field) => {
-        if (field === "user-id") {
+        switch (field) {
-            looked_for_existing = true;
+            case "user-id":
-            return "34";
+                looked_for_existing = true;
+                return "34";
+            /* istanbul ignore next */
+            case "stream-id":
+                return "111";
+            /* istanbul ignore next */
+            default:
+                throw new Error(`Unknown field ${field}`);
         }
-        if (field === "stream-id") {
-            return "111";
-        }
-        throw new Error(`Unknown field ${field}`);
     };
 
     const $previous_users = $("#compose_invite_users .compose_invite_user");

frontend_tests/node_tests/compose_video.js

@@ -32,6 +32,7 @@ const compose = zrequire("compose");
 function stub_out_video_calls() {
     const $elem = $("#below-compose-content .video_link");
     $elem.toggle = (show) => {
+        /* istanbul ignore if */
         if (show) {
             $elem.show();
         } else {
@@ -77,8 +78,6 @@ test("videos", ({override, override_rewire}) => {
     compose.initialize();
 
     (function test_no_provider_video_link_compose_clicked() {
-        let called = false;
-
         const $textarea = $.create("target-stub");
         $textarea.set_parents_result(".message_edit_form", []);
 
@@ -90,15 +89,19 @@ test("videos", ({override, override_rewire}) => {
             },
         };
 
-        override_rewire(compose_ui, "insert_syntax_and_focus", () => {
+        override_rewire(
-            called = true;
+            compose_ui,
-        });
+            "insert_syntax_and_focus",
+            /* istanbul ignore next */
+            () => {
+                throw new Error("unexpected insert_syntax_and_focus call");
+            },
+        );
 
         const handler = $("body").get_on_handler("click", ".video_link");
         $("#compose-textarea").val("");
 
         handler(ev);
-        assert.ok(!called);
     })();
 
     (function test_jitsi_video_link_compose_clicked() {

frontend_tests/node_tests/composebox_typeahead.js

@@ -54,9 +54,6 @@ const composebox_typeahead = zrequire("composebox_typeahead");
 const settings_config = zrequire("settings_config");
 const pygments_data = zrequire("../generated/pygments_data.json");
 
-// To be eliminated in next commit:
-stream_data.__Rewire__("set_filter_out_inactives", () => false);
-
 const ct = composebox_typeahead;
 
 // Use a slightly larger value than what's user-facing
@@ -143,19 +140,10 @@ const emojis_by_name = new Map(
         headphones: emoji_headphones,
     }),
 );
-const emoji_list = Array.from(emojis_by_name.values(), (emoji_dict) => {
+const emoji_list = Array.from(emojis_by_name.values(), (emoji_dict) => ({
-    if (emoji_dict.is_realm_emoji === true) {
+    emoji_name: emoji_dict.name,
-        return {
+    emoji_code: emoji_dict.emoji_code,
-            emoji_name: emoji_dict.name,
+}));
-            emoji_url: emoji_dict.url,
-            is_realm_emoji: true,
-        };
-    }
-    return {
-        emoji_name: emoji_dict.name,
-        emoji_code: emoji_dict.emoji_code,
-    };
-});
 
 const me_slash = {
     name: "me",
@@ -1070,14 +1058,8 @@ test("initialize", ({override, override_rewire, mock_template}) => {
         stopPropagation: noop,
     };
 
-    $("#stream_message_recipient_topic").data = () => ({typeahead: {shown: true}});
     $("form#send_message_form").trigger(event);
 
-    const stub_typeahead_hidden = () => ({typeahead: {shown: false}});
-    $("#stream_message_recipient_topic").data = stub_typeahead_hidden;
-    $("#stream_message_recipient_stream").data = stub_typeahead_hidden;
-    $("#private_message_recipient").data = stub_typeahead_hidden;
-    $("#compose-textarea").data = stub_typeahead_hidden;
     $("form#send_message_form").trigger(event);
 
     event.key = "Tab";
@@ -1144,7 +1126,6 @@ test("initialize", ({override, override_rewire, mock_template}) => {
         preventDefault: noop,
     };
     // We trigger keydown in order to make nextFocus !== false
-    $("#stream_message_recipient_topic").data = () => ({typeahead: {shown: true}});
     $("form#send_message_form").trigger(event);
     $("#stream_message_recipient_topic").off("mouseup");
     event.type = "keyup";

frontend_tests/node_tests/dropdown_list_widget.js

@@ -78,7 +78,7 @@ run_test("no_default_value", () => {
         widget_name: "my_setting",
         data: ["one", "two", "three"].map((x) => ({name: x, value: x})),
         default_text: $t({defaultMessage: "not set"}),
-        render_text: (text) => `rendered: ${text}`,
+        render_text: /* istanbul ignore next */ (text) => `rendered: ${text}`,
         null_value: "null-value",
     };
 

frontend_tests/node_tests/example6.js

@@ -17,11 +17,13 @@ run_test("explore make_stub", ({override}) => {
     // Let's say you have to test the following code.
 
     const app = {
+        /* istanbul ignore next */
         notify_server_of_deposit(deposit_amount) {
             // simulate difficulty
             throw new Error(`We cannot report this value without wifi: ${deposit_amount}`);
         },
 
+        /* istanbul ignore next */
         pop_up_fancy_confirmation_screen(deposit_amount, label) {
             // simulate difficulty
             throw new Error(`We cannot make a ${label} dialog for amount ${deposit_amount}`);

frontend_tests/node_tests/example7.js

@@ -91,8 +91,6 @@ run_test("unread_ops", ({override, override_rewire}) => {
 
     // We don't want recent topics to process message for this test.
     override_rewire(recent_topics_util, "is_visible", () => false);
-    // Show message_viewport as not visible so that messages will be stored as unread.
-    override(message_viewport, "is_visible_and_focused", () => false);
 
     // Make our test message appear to be unread, so that
     // we then need to subsequently process them as read.

frontend_tests/node_tests/hotkey.js

@@ -105,7 +105,6 @@ message_lists.current = {
             flags: ["read", "starred"],
         };
     },
-    selected_row() {},
     get_row() {
         return 101;
     },
@@ -138,7 +137,6 @@ function stubbing_rewire(module, func_name_to_stub, test_function) {
 }
 
 // Set up defaults for most tests.
-hotkey.__Rewire__("in_content_editable_widget", () => false);
 hotkey.__Rewire__("processing_text", () => false);
 
 run_test("mappings", () => {
@@ -228,7 +226,7 @@ function process(s) {
     };
     try {
         return hotkey.process_keypress(e);
-    } catch (error) {
+    } catch (error) /* istanbul ignore next */ {
         // An exception will be thrown here if a different
         // function is called than the one declared.  Try to
         // provide a useful error message.
@@ -292,8 +290,8 @@ run_test("allow normal typing when processing text", ({override_rewire}) => {
 
 run_test("streams", ({override}) => {
     settings_data.user_can_create_private_streams = () => true;
-    settings_data.user_can_create_public_streams = () => true;
+    delete settings_data.user_can_create_public_streams;
-    settings_data.user_can_create_web_public_streams = () => true;
+    delete settings_data.user_can_create_web_public_streams;
     override(overlays, "streams_open", () => true);
     override(overlays, "is_active", () => true);
     assert_mapping("S", stream_settings_ui, "keyboard_sub");
@@ -435,7 +433,7 @@ run_test("motion_keys", () => {
 
         try {
             return hotkey.process_keydown(e);
-        } catch (error) {
+        } catch (error) /* istanbul ignore next */ {
             // An exception will be thrown here if a different
             // function is called than the one declared.  Try to
             // provide a useful error message.
@@ -493,12 +491,12 @@ run_test("motion_keys", () => {
     overlays.streams_open = () => true;
     assert_mapping("up_arrow", stream_settings_ui, "switch_rows");
     assert_mapping("down_arrow", stream_settings_ui, "switch_rows");
-    overlays.streams_open = () => false;
+    delete overlays.streams_open;
 
     overlays.lightbox_open = () => true;
     assert_mapping("left_arrow", lightbox, "prev");
     assert_mapping("right_arrow", lightbox, "next");
-    overlays.lightbox_open = () => false;
+    delete overlays.lightbox_open;
 
     overlays.settings_open = () => true;
     assert_unmapped("end");
@@ -507,12 +505,12 @@ run_test("motion_keys", () => {
     assert_unmapped("page_up");
     assert_unmapped("page_down");
     assert_unmapped("spacebar");
-    overlays.settings_open = () => false;
+    delete overlays.settings_open;
 
-    overlays.is_active = () => true;
+    delete overlays.is_active;
     overlays.drafts_open = () => true;
     assert_mapping("up_arrow", drafts, "drafts_handle_events");
     assert_mapping("down_arrow", drafts, "drafts_handle_events");
-    overlays.is_active = () => false;
+    delete overlays.is_active;
-    overlays.drafts_open = () => false;
+    delete overlays.drafts_open;
 });

frontend_tests/node_tests/input_pill.js

@@ -644,7 +644,7 @@ run_test("appendValue/clear", ({mock_template}) => {
     const config = {
         $container,
         create_item_from_text: (s) => ({type: "color", display_value: s}),
-        get_text_from_item: (s) => s.display_value,
+        get_text_from_item: /* istanbul ignore next */ (s) => s.display_value,
     };
 
     $pill_input.before = () => {};

frontend_tests/node_tests/keydown_util.js

@@ -11,7 +11,7 @@ run_test("test_early_returns", () => {
     const opts = {
         $elem: $stub,
         handlers: {
-            ArrowLeft: () => {
+            ArrowLeft: /* istanbul ignore next */ () => {
                 throw new Error("do not dispatch this with alt key");
             },
         },

frontend_tests/node_tests/list_cursor.js

@@ -34,8 +34,8 @@ function basic_conf({first_key, prev_key, next_key}) {
 run_test("misc errors", ({override}) => {
     const conf = basic_conf({
         first_key: () => undefined,
-        prev_key: () => undefined,
+        prev_key: /* istanbul ignore next */ () => undefined,
-        next_key: () => undefined,
+        next_key: /* istanbul ignore next */ () => undefined,
     });
 
     const cursor = new ListCursor(conf);
@@ -64,7 +64,7 @@ run_test("single item list", ({override}) => {
     const valid_key = "42";
 
     const conf = basic_conf({
-        first_key: () => valid_key,
+        first_key: /* istanbul ignore next */ () => valid_key,
         next_key: () => undefined,
         prev_key: () => undefined,
     });
@@ -91,7 +91,7 @@ run_test("single item list", ({override}) => {
 
 run_test("multiple item list", ({override}) => {
     const conf = basic_conf({
-        first_key: () => 1,
+        first_key: /* istanbul ignore next */ () => 1,
         next_key: (key) => (key < 3 ? key + 1 : undefined),
         prev_key: (key) => (key > 1 ? key - 1 : undefined),
     });

frontend_tests/node_tests/list_widget.js

@@ -43,13 +43,6 @@ const ListWidget = zrequire("list_widget");
 function make_container() {
     const $container = {};
 
-    $container.length = () => 1;
-    $container.is = () => false;
-    $container.css = (prop) => {
-        assert.equal(prop, "max-height");
-        return "none";
-    };
-
     // Make our append function just set a field we can
     // check in our tests.
     $container.append = ($data) => {
@@ -123,6 +116,7 @@ function make_search_input() {
 
     // Allow ourselves to be wrapped by $(...) and
     // return ourselves.
+    /* istanbul ignore next */
     $element.to_jquery = () => $element;
 
     $element.on = (event_name, f) => {
@@ -322,6 +316,7 @@ function sort_button(opts) {
                 return opts.sort_type;
             case "sort-prop":
                 return opts.prop_name;
+            /* istanbul ignore next */
             default:
                 throw new Error("unknown selector: " + sel);
         }
@@ -549,7 +544,7 @@ run_test("clear_event_handlers", () => {
         modifier: () => {},
         filter: {
             $element: $filter_element,
-            predicate: () => true,
+            predicate: /* istanbul ignore next */ () => true,
         },
         $simplebar_container: $scroll_container,
     };
@@ -602,8 +597,8 @@ run_test("errors", () => {
     blueslip.expect("error", "Filterer and predicate are mutually exclusive.");
     ListWidget.create($container, list, {
         filter: {
-            filterer: () => true,
+            filterer: /* istanbul ignore next */ () => true,
-            predicate: () => true,
+            predicate: /* istanbul ignore next */ () => true,
         },
         $simplebar_container: $scroll_container,
     });
@@ -795,7 +790,8 @@ run_test("render item", () => {
     blueslip.expect("error", "html_selector should be a function.");
     ListWidget.create($container, list, {
         name: "replace-list",
-        modifier: (item) => `<tr data-item=${item.value}>${item.text}</tr>\n`,
+        modifier: /* istanbul ignore next */ (item) =>
+            `<tr data-item=${item.value}>${item.text}</tr>\n`,
         get_item,
         html_selector: "hello world",
         $simplebar_container: $scroll_container,
@@ -855,6 +851,7 @@ run_test("Multiselect dropdown retain_selected_items", () => {
             if (element) {
                 return true;
             }
+            /* istanbul ignore next */
             return false;
         }
 

frontend_tests/node_tests/markdown.js

@@ -27,11 +27,6 @@ const example_realm_linkifiers = [
 ];
 user_settings.translate_emoticons = false;
 
-function Image() {
-    return {};
-}
-set_global("Image", Image);
-
 set_global("document", {compatMode: "CSS1Compat"});
 
 const emoji = zrequire("emoji");
@@ -244,6 +239,7 @@ test("marked_shared", () => {
 
     for (const test of tests) {
         // Ignore tests if specified
+        /* istanbul ignore if */
         if (test.ignore === true) {
             continue;
         }

frontend_tests/node_tests/markdown_parse.js

@@ -24,7 +24,8 @@ function get_user_id_from_name(name) {
         }
     }
 
-    return undefined;
+    /* istanbul ignore next */
+    throw new Error(`unexpected name ${name}`);
 }
 
 function is_valid_full_name_and_user_id(name, user_id) {
@@ -99,7 +100,8 @@ function get_emoji_name(codepoint) {
         }
     }
 
-    return undefined;
+    /* istanbul ignore next */
+    throw new Error(`unexpected codepoint ${codepoint}`);
 }
 
 const realm_emoji_map = new Map();

frontend_tests/node_tests/message_fetch.js

@@ -93,17 +93,13 @@ function config_fake_channel(conf) {
         // There's a separate call with anchor="newest" that happens
         // unconditionally; do basic verification of that call.
         if (opts.data.anchor === "newest") {
-            if (!called_with_newest_flag) {
+            assert.ok(!called_with_newest_flag, "Only one 'newest' call allowed");
-                called_with_newest_flag = true;
+            called_with_newest_flag = true;
-                assert.equal(opts.data.num_after, 0);
+            assert.equal(opts.data.num_after, 0);
-                return;
+            return;
-            }
-            throw new Error("Only one 'newest' call allowed");
         }
 
-        if (called && !conf.can_call_again) {
+        assert.ok(!called || conf.can_call_again, "only use this for one call");
-            throw new Error("only use this for one call");
-        }
         if (!conf.can_call_again) {
             assert.equal(self.success, undefined);
         }

frontend_tests/node_tests/message_list_data.js

@@ -2,19 +2,10 @@
 
 const {strict: assert} = require("assert");
 
-const {
+const {with_function_call_disallowed_rewire, zrequire} = require("../zjsunit/namespace");
-    set_global,
-    with_function_call_disallowed_rewire,
-    zrequire,
-} = require("../zjsunit/namespace");
 const {run_test} = require("../zjsunit/test");
 const blueslip = require("../zjsunit/zblueslip");
 
-set_global("setTimeout", (f, delay) => {
-    assert.equal(delay, 0);
-    return f();
-});
-
 const muted_topics = zrequire("muted_topics");
 const muted_users = zrequire("muted_users");
 const {MessageListData} = zrequire("../js/message_list_data");

frontend_tests/node_tests/message_list_view.js

@@ -6,14 +6,11 @@ const _ = require("lodash");
 
 const {mock_esm, set_global, zrequire} = require("../zjsunit/namespace");
 const {run_test} = require("../zjsunit/test");
-const {user_settings} = require("../zjsunit/zpage_params");
 
 set_global("document", "document-stub");
 
 const noop = () => {};
 
-user_settings.twenty_four_hour_time = false;
-
 mock_esm("../../static/js/message_lists", {home: "stub"});
 
 // timerender calls setInterval when imported
@@ -25,9 +22,6 @@ mock_esm("../../static/js/timerender", {
         return [{outerHTML: String(time1.getTime()) + " - " + String(time2.getTime())}];
     },
     stringify_time(time) {
-        if (user_settings.twenty_four_hour_time) {
-            return time.toString("HH:mm");
-        }
         return time.toString("h:mm TT");
     },
 });

frontend_tests/node_tests/narrow_activate.js

@@ -160,13 +160,6 @@ run_test("basics", () => {
 
     all_messages_data.all_messages_data = {
         all_messages: () => messages,
-        get: (msg_id) => {
-            assert.equal(msg_id, selected_id);
-            return selected_message;
-        },
-        fetch_status: {
-            has_found_newest: () => true,
-        },
         empty: () => false,
         first: () => ({id: 900}),
         last: () => ({id: 1100}),

frontend_tests/node_tests/narrow_unread.js

@@ -26,7 +26,6 @@ const alice = {
 
 people.init();
 people.add_active_user(alice);
-people.is_my_user_id = () => false;
 
 function set_filter(terms) {
     const filter = new Filter(terms);

frontend_tests/node_tests/navbar_alerts.js

@@ -56,13 +56,17 @@ test("allow_notification_alert", () => {
     assert.equal(navbar_alerts.should_show_notifications(ls), false);
 
     // Avoid showing if notification is already granted.
+    /* istanbul ignore next */
     notifications.permission_state = () => "granted";
     notifications.granted_desktop_notifications_permission = () => "granted";
     assert.equal(navbar_alerts.should_show_notifications(ls), false);
 
     // Don't ask for permission to spectator.
+    /* istanbul ignore next */
     util.is_mobile = () => false;
+    /* istanbul ignore next */
     notifications.granted_desktop_notifications_permission = () => false;
+    /* istanbul ignore next */
     notifications.permission_state = () => "granted";
     page_params.is_spectator = true;
     assert.equal(navbar_alerts.should_show_notifications(ls), false);

frontend_tests/node_tests/password.js

@@ -11,12 +11,15 @@ function password_field(min_length, min_guesses) {
     const self = {};
 
     self.data = (field) => {
-        if (field === "minLength") {
+        switch (field) {
-            return min_length;
+            case "minLength":
-        } else if (field === "minGuesses") {
+                return min_length;
-            return min_guesses;
+            case "minGuesses":
+                return min_guesses;
+            /* istanbul ignore next */
+            default:
+                throw new Error(`Unknown field ${field}`);
         }
-        throw new Error(`Unknown field ${field}`);
     };
 
     return self;

frontend_tests/node_tests/people.js

@@ -835,9 +835,13 @@ test_people("extract_people_from_message", ({override_rewire}) => {
     assert.ok(reported);
 
     // Get line coverage
-    people.__Rewire__("report_late_add", () => {
+    people.__Rewire__(
-        throw new Error("unexpected late add");
+        "report_late_add",
-    });
+        /* istanbul ignore next */
+        () => {
+            throw new Error("unexpected late add");
+        },
+    );
 
     message = {
         type: "private",

frontend_tests/node_tests/reactions.js

@@ -49,9 +49,6 @@ const spectators = mock_esm("../../static/js/spectators", {
 });
 
 message_lists.current = {
-    selected_message() {
-        return {sent_by_me: true};
-    },
     selected_row() {
         return $(".selected-row");
     },

frontend_tests/node_tests/recent_topics.js

@@ -63,9 +63,11 @@ const ListWidget = mock_esm("../../static/js/list_widget", {
     hard_redraw: noop,
     render_item: (item) => ListWidget.modifier(item),
     replace_list_data: (data) => {
-        if (expected_data_to_replace_in_list_widget === undefined) {
+        assert.notEqual(
-            throw new Error("You must set expected_data_to_replace_in_list_widget");
+            expected_data_to_replace_in_list_widget,
-        }
+            undefined,
+            "You must set expected_data_to_replace_in_list_widget",
+        );
         assert.deepEqual(data, expected_data_to_replace_in_list_widget);
         expected_data_to_replace_in_list_widget = undefined;
     },
@@ -110,7 +112,6 @@ mock_esm("../../static/js/stream_data", {
         // We only test via muted topics for now.
         // TODO: Make muted streams and test them.
         false,
-    is_subscribed: () => true,
 });
 mock_esm("../../static/js/stream_list", {
     handle_narrow_deactivated: noop,

frontend_tests/node_tests/rendered_markdown.js

@@ -88,6 +88,7 @@ const get_content_element = () => {
 
     // Fend off dumb security bugs by forcing devs to be
     // intentional about HTML manipulation.
+    /* istanbul ignore next */
     function security_violation() {
         throw new Error(`
             Be super careful about HTML manipulation.
@@ -401,9 +402,7 @@ function test_code_playground(mock_template, viewing_code) {
     // our case "fake" zjquery objects).
     const prepends = [];
     $pre.prepend = (arg) => {
-        if (!arg.__zjquery) {
+        assert.ok(arg.__zjquery, "We should only prepend jQuery objects.");
-            throw new Error("We should only prepend jQuery objects.");
-        }
         prepends.push(arg);
     };
 

frontend_tests/node_tests/search_future.js

@@ -2,7 +2,7 @@
 
 const {strict: assert} = require("assert");
 
-const {mock_esm, set_global, zrequire} = require("../zjsunit/namespace");
+const {mock_esm, zrequire} = require("../zjsunit/namespace");
 const {run_test} = require("../zjsunit/test");
 const $ = require("../zjsunit/zjquery");
 const {page_params} = require("../zjsunit/zpage_params");
@@ -25,8 +25,6 @@ mock_esm("../../static/js/ui_util", {
     place_caret_at_end: noop,
 });
 
-set_global("setTimeout", (func) => func());
-
 const search = zrequire("search");
 const search_pill = zrequire("search_pill");
 const {Filter} = zrequire("../js/filter");
@@ -63,14 +61,14 @@ test("update_button_visibility", () => {
 
     $search_query.is = () => true;
     $search_query.val("");
-    narrow_state.active = () => false;
+    delete narrow_state.active;
     $search_button.prop("disabled", true);
     search.update_button_visibility();
     assert.ok(!$search_button.prop("disabled"));
 
     $search_query.is = () => false;
     $search_query.val("Test search term");
-    narrow_state.active = () => false;
+    delete narrow_state.active;
     $search_button.prop("disabled", true);
     search.update_button_visibility();
     assert.ok(!$search_button.prop("disabled"));
@@ -144,9 +142,13 @@ test("initialize", () => {
             let operators;
             let is_blurred;
             let is_append_search_string_called;
-            $search_query_box.on("blur", () => {
+            $search_query_box.on(
-                is_blurred = true;
+                "blur",
-            });
+                /* istanbul ignore next */
+                () => {
+                    is_blurred = true;
+                },
+            );
             search_pill.append_search_string = () => {
                 is_append_search_string_called = true;
             };
@@ -155,14 +157,17 @@ test("initialize", () => {
                 is_blurred = false;
                 is_append_search_string_called = false;
                 $search_query_box.val(search_box_val);
+                /* istanbul ignore next */
                 Filter.parse = (search_string) => {
                     assert.equal(search_string, search_box_val);
                     return operators;
                 };
+                /* istanbul ignore next */
                 narrow.activate = (raw_operators, options) => {
                     assert.deepEqual(raw_operators, operators);
                     assert.deepEqual(options, {trigger: "search"});
                 };
+                /* istanbul ignore next */
                 search_pill.get_search_string_for_current_filter = () => search_box_val;
             };
 
@@ -285,6 +290,7 @@ test("initialize", () => {
         type: "keyup",
         which: 15,
     };
+    /* istanbul ignore next */
     $search_query_box.is = () => false;
     $searchbox_form.trigger(ev);
 

frontend_tests/node_tests/search_now.js

@@ -53,14 +53,14 @@ run_test("update_button_visibility", () => {
 
     $search_query.is = () => true;
     $search_query.val("");
-    narrow_state.active = () => false;
+    delete narrow_state.active;
     $search_button.prop("disabled", true);
     search.update_button_visibility();
     assert.ok(!$search_button.prop("disabled"));
 
     $search_query.is = () => false;
     $search_query.val("Test search term");
-    narrow_state.active = () => false;
+    delete narrow_state.active;
     $search_button.prop("disabled", true);
     search.update_button_visibility();
     assert.ok(!$search_button.prop("disabled"));
@@ -247,6 +247,7 @@ run_test("initialize", () => {
     _setup("");
 
     ev.key = "a";
+    /* istanbul ignore next */
     $search_query_box.is = () => false;
     $searchbox_form.trigger(ev);
 

frontend_tests/node_tests/search_suggestion_future.js

@@ -676,8 +676,9 @@ test("topic_suggestions", ({override, override_rewire}) => {
                 return office_id;
             case "devel":
                 return devel_id;
+            /* istanbul ignore next */
             default:
-                return undefined;
+                throw new Error(`unknown stream ${stream_name}`);
         }
     });
 

frontend_tests/node_tests/search_suggestion_now.js

@@ -641,8 +641,9 @@ test("topic_suggestions", ({override, override_rewire}) => {
                 return office_id;
             case "devel":
                 return devel_id;
+            /* istanbul ignore next */
             default:
-                return undefined;
+                throw new Error(`unknown stream ${stream_name}`);
         }
     });
 

frontend_tests/node_tests/server_events.js

@@ -40,9 +40,6 @@ mock_esm("../../static/js/ui_report", {
     hide_error() {
         return false;
     },
-    show_error() {
-        return false;
-    },
 });
 
 mock_esm("../../static/js/stream_events", {

frontend_tests/node_tests/settings_muted_topics.js

@@ -60,15 +60,16 @@ run_test("settings", ({override_rewire}) => {
 
     let topic_data_called = 0;
     $topic_tr_html.attr = (opts) => {
-        if (opts === "data-stream-id") {
+        topic_data_called += 1;
-            topic_data_called += 1;
+        switch (opts) {
-            return frontend.stream_id;
+            case "data-stream-id":
+                return frontend.stream_id;
+            case "data-topic":
+                return "js";
+            /* istanbul ignore next */
+            default:
+                throw new Error(`Unknown attribute ${opts}`);
         }
-        if (opts === "data-topic") {
-            topic_data_called += 1;
-            return "js";
-        }
-        throw new Error(`Unknown attribute ${opts}`);
     };
 
     let unmute_topic_called = false;

frontend_tests/node_tests/settings_muted_users.js

@@ -51,11 +51,9 @@ run_test("settings", ({override_rewire}) => {
 
     let row_attribute_fetched = false;
     $fake_row.attr = (opts) => {
-        if (opts === "data-user-id") {
+        assert.equal(opts, "data-user-id");
-            row_attribute_fetched += 1;
+        row_attribute_fetched += 1;
-            return "5";
+        return "5";
-        }
-        throw new Error(`Unknown attribute ${opts}`);
     };
 
     let unmute_user_called = false;

frontend_tests/node_tests/settings_org.js

@@ -47,7 +47,6 @@ const settings_bots = zrequire("settings_bots");
 const stream_settings_data = zrequire("stream_settings_data");
 const settings_account = zrequire("settings_account");
 const settings_org = zrequire("settings_org");
-const sub_store = zrequire("sub_store");
 const dropdown_list_widget = zrequire("dropdown_list_widget");
 
 function test(label, f) {
@@ -195,7 +194,6 @@ function test_submit_settings_form(override, submit_form) {
     let stubs = createSaveButtons(subsection);
     let $save_button = stubs.$save_button;
     $save_button.attr("id", `org-submit-${subsection}`);
-    $save_button.replace = () => `${subsection}`;
 
     $("#id_realm_waiting_period_threshold").val(10);
 
@@ -241,6 +239,7 @@ function test_submit_settings_form(override, submit_form) {
         $add_custom_emoji_policy_elem,
         $create_public_stream_policy_elem,
         $create_private_stream_policy_elem,
+        $invite_to_realm_policy_elem,
         $invite_to_stream_policy_elem,
     ]);
 
@@ -250,6 +249,7 @@ function test_submit_settings_form(override, submit_form) {
 
     let expected_value = {
         bot_creation_policy: 1,
+        invite_to_realm_policy: 2,
         invite_to_stream_policy: 1,
         email_address_visibility: 1,
         add_custom_emoji_policy: 1,
@@ -925,10 +925,6 @@ test("misc", ({override_rewire}) => {
     let setting_name = "realm_notifications_stream_id";
     let $elem = $(`#${CSS.escape(setting_name)}_widget #${CSS.escape(setting_name)}_name`);
     $elem.closest = () => $stub_notification_disable_parent;
-    sub_store.__Rewire__("get", (stream_id) => {
-        assert.equal(stream_id, 42);
-        return {name: "some_stream"};
-    });
     settings_org.notifications_stream_widget.render(42);
     assert.equal($elem.text(), "#some_stream");
     assert.ok(!$elem.hasClass("text-warning"));
@@ -940,10 +936,6 @@ test("misc", ({override_rewire}) => {
     setting_name = "realm_signup_notifications_stream_id";
     $elem = $(`#${CSS.escape(setting_name)}_widget #${CSS.escape(setting_name)}_name`);
     $elem.closest = () => $stub_notification_disable_parent;
-    sub_store.__Rewire__("get", (stream_id) => {
-        assert.equal(stream_id, 75);
-        return {name: "some_stream"};
-    });
     settings_org.signup_notifications_stream_widget.render(75);
     assert.equal($elem.text(), "#some_stream");
     assert.ok(!$elem.hasClass("text-warning"));

frontend_tests/node_tests/settings_user_groups.js

@@ -116,8 +116,6 @@ test_ui("populate_user_groups", ({override_rewire, mock_template}) => {
 
     user_groups.get_realm_user_groups = () => [realm_user_group];
 
-    people.get_visible_email = () => bob.email;
-
     let templates_render_called = false;
     const $fake_rendered_temp = $.create("fake_admin_user_group_list_template_rendered");
     mock_template("settings/admin_user_group_list.hbs", false, (args) => {
@@ -139,12 +137,6 @@ test_ui("populate_user_groups", ({override_rewire, mock_template}) => {
         if (user_id === iago.user_id) {
             return iago;
         }
-        if (user_id === alice.user_id) {
-            return alice;
-        }
-        if (user_id === undefined) {
-            return noop;
-        }
         assert.equal(user_id, 4);
         blueslip.expect("warn", "Undefined user in function append_user");
         get_by_user_id_called = true;
@@ -246,9 +238,6 @@ test_ui("populate_user_groups", ({override_rewire, mock_template}) => {
                 saved_fade_out_called = true;
             };
             $(cancel_selector).css = (data) => {
-                if (typeof data === "string") {
-                    assert.equal(data, "display");
-                }
                 assert.equal(typeof data, "object");
                 assert.equal(data.display, "inline-block");
                 assert.equal(data.opacity, "0");
@@ -258,9 +247,6 @@ test_ui("populate_user_groups", ({override_rewire, mock_template}) => {
                 cancel_fade_to_called = true;
             };
             $(instructions_selector).css = (data) => {
-                if (typeof data === "string") {
-                    assert.equal(data, "display");
-                }
                 assert.equal(typeof data, "object");
                 assert.equal(data.display, "block");
                 assert.equal(data.opacity, "0");
@@ -284,17 +270,15 @@ test_ui("populate_user_groups", ({override_rewire, mock_template}) => {
     let get_by_email_called = false;
     people.get_by_email = (user_email) => {
         get_by_email_called = true;
-        if (user_email === iago.email) {
+        switch (user_email) {
-            return iago;
+            case iago.email:
+                return iago;
+            case bob.email:
+                return bob;
+            /* istanbul ignore next */
+            default:
+                throw new Error("Expected user email to be of Iago or Bob here.");
         }
-        if (user_email === bob.email) {
-            return bob;
-        }
-        throw new Error("Expected user email to be of Alice or Iago here.");
-    };
-    pills.onPillCreate = (handler) => {
-        assert.equal(typeof handler, "function");
-        handler();
     };
 
     function test_create_item(handler) {
@@ -363,8 +347,9 @@ test_ui("with_external_user", ({override_rewire, mock_template}) => {
 
     user_groups.get_realm_user_groups = () => [realm_user_group];
 
-    // We return noop because these are already tested, so we skip them
+    // We return [] because these are already tested, so we skip them
-    people.get_realm_users = () => noop;
+    /* istanbul ignore next */
+    people.get_realm_users = () => [];
 
     mock_template(
         "settings/admin_user_group_list.hbs",
@@ -372,9 +357,9 @@ test_ui("with_external_user", ({override_rewire, mock_template}) => {
         () => "settings/admin_user_group_list.hbs",
     );
 
-    people.get_by_user_id = () => noop;
+    people.get_by_user_id = () => "user stub";
 
-    override_rewire(user_pill, "append_person", () => noop);
+    override_rewire(user_pill, "append_person", noop);
 
     let can_edit_called = 0;
     override_rewire(settings_user_groups, "can_edit", () => {
@@ -391,30 +376,32 @@ test_ui("with_external_user", ({override_rewire, mock_template}) => {
     const $description_field_stub = $.create("fake-description-field");
     const $input_stub = $.create("fake-input");
     $user_group_stub.find = (elem) => {
-        if (elem === ".name") {
+        user_group_find_called += 1;
-            user_group_find_called += 1;
+        switch (elem) {
-            return $name_field_stub;
+            case ".name":
+                return $name_field_stub;
+            case ".description":
+                return $description_field_stub;
+            /* istanbul ignore next */
+            default:
+                throw new Error(`Unknown element ${elem}`);
         }
-        if (elem === ".description") {
-            user_group_find_called += 1;
-            return $description_field_stub;
-        }
-        throw new Error(`Unknown element ${elem}`);
     };
 
     const $pill_container_stub = $(`.pill-container[data-group-pills="${CSS.escape(1)}"]`);
     const $pill_stub = $.create("fake-pill");
     let pill_container_find_called = 0;
     $pill_container_stub.find = (elem) => {
-        if (elem === ".input") {
+        pill_container_find_called += 1;
-            pill_container_find_called += 1;
+        switch (elem) {
-            return $input_stub;
+            case ".input":
+                return $input_stub;
+            case ".pill":
+                return $pill_stub;
+            /* istanbul ignore next */
+            default:
+                throw new Error(`Unknown element ${elem}`);
         }
-        if (elem === ".pill") {
-            pill_container_find_called += 1;
-            return $pill_stub;
-        }
-        throw new Error(`Unknown element ${elem}`);
     };
 
     $input_stub.css = (property, val) => {
@@ -437,10 +424,10 @@ test_ui("with_external_user", ({override_rewire, mock_template}) => {
         assert.equal(value, "0.5");
     };
 
-    // We return noop because these are already tested, so we skip them
+    // We return [] because these are already tested, so we skip them
-    $pill_container_stub.children = () => noop;
+    $pill_container_stub.children = () => [];
 
-    $("#user-groups").append = () => noop;
+    $("#user-groups").append = noop;
 
     reset_test_setup($pill_container_stub);
 
@@ -621,6 +608,7 @@ test_ui("on_events", ({override_rewire, mock_template}) => {
     (function test_do_not_blur() {
         const blur_event_classes = [".name", ".description", ".input"];
         let api_endpoint_called = false;
+        /* istanbul ignore next */
         channel.post = () => {
             api_endpoint_called = true;
         };
@@ -658,10 +646,8 @@ test_ui("on_events", ({override_rewire, mock_template}) => {
 
             api_endpoint_called = false;
             $fake_this.closest = (class_name) => {
-                if (class_name === ".typeahead") {
+                assert.equal(class_name, ".typeahead");
-                    return [1];
+                return [1];
-                }
-                return [];
             };
             handler.call($fake_this, event);
             assert.ok(!api_endpoint_called);
@@ -755,9 +741,6 @@ test_ui("on_events", ({override_rewire, mock_template}) => {
             cancel_fade_out_called = true;
         };
         $(saved_selector).css = (data) => {
-            if (typeof data === "string") {
-                assert.equal(data, "display");
-            }
             assert.equal(typeof data, "object");
             assert.equal(data.display, "inline-block");
             assert.equal(data.opacity, "0");

frontend_tests/node_tests/stream_settings_ui.js

@@ -10,7 +10,6 @@ const denmark_stream_id = 101;
 
 const ui = mock_esm("../../static/js/ui", {
     get_content_element: ($element) => $element,
-    get_scroll_element: ($element) => $element,
 });
 
 mock_esm("../../static/js/hash_util", {

frontend_tests/node_tests/stream_topic_history.js

@@ -81,7 +81,7 @@ test("basics", () => {
     max_message_id = stream_topic_history.get_max_message_id(stream_id);
     assert.deepEqual(max_message_id, 103);
 
-    message_util.get_messages_in_topic = () => [{id: 102}];
+    delete message_util.get_messages_in_topic;
     // Removing first topic1 message has no effect.
     stream_topic_history.remove_messages({
         stream_id,
@@ -163,8 +163,6 @@ test("server_history", () => {
     const stream_id = sub.stream_id;
     stream_data.add_sub(sub);
 
-    all_messages_data.all_messages_data.fetch_status.has_found_newest = () => false;
-
     assert.equal(stream_topic_history.is_complete_for_stream_id(stream_id), false);
 
     stream_topic_history.add_message({
@@ -332,6 +330,7 @@ test("server_history_end_to_end", () => {
 
     // Try getting server history for a second time.
 
+    /* istanbul ignore next */
     channel.get = () => {
         throw new Error("We should not get more data.");
     };

frontend_tests/node_tests/transmit.js

@@ -60,9 +60,14 @@ run_test("transmit_message_ajax", () => {
 });
 
 run_test("transmit_message_ajax_reload_pending", () => {
+    /* istanbul ignore next */
     const success = () => {
         throw new Error("unexpected success");
     };
+    /* istanbul ignore next */
+    const error = () => {
+        throw new Error("unexpected error");
+    };
 
     reload_state.is_pending = () => true;
 
@@ -80,13 +85,6 @@ run_test("transmit_message_ajax_reload_pending", () => {
 
     const request = {foo: "bar"};
 
-    let error_func_called;
-    const error = (response) => {
-        assert.equal(response, "Error sending message");
-        error_func_called = true;
-    };
-
-    error_func_called = false;
     channel.post = (opts) => {
         assert.equal(opts.url, "/json/messages");
         assert.equal(opts.data.foo, "bar");
@@ -94,7 +92,6 @@ run_test("transmit_message_ajax_reload_pending", () => {
         opts.error(xhr, "bad request");
     };
     transmit.send_message(request, success, error);
-    assert.ok(!error_func_called);
     assert.ok(reload_initiated);
 });
 
@@ -143,8 +140,6 @@ run_test("reply_message_private", ({override_rewire}) => {
     };
     people.add_active_user(fred);
 
-    people.is_my_user_id = () => false;
-
     const pm_message = {
         type: "private",
         display_recipient: [{id: fred.user_id}],

frontend_tests/node_tests/typeahead_helper.js

@@ -453,6 +453,7 @@ test("sort_recipients pm counts", () => {
         "zman@test.net",
     ]);
 
+    /* istanbul ignore next */
     function compare() {
         throw new Error("We do not expect to need a tiebreaker here.");
     }

frontend_tests/node_tests/unread.js

@@ -250,10 +250,8 @@ test("num_unread_for_topic", ({override_rewire}) => {
     const stream_id = 301;
 
     override_rewire(sub_store, "get", (arg) => {
-        if (arg === stream_id) {
+        assert.equal(arg, stream_id);
-            return {name: "Some stream"};
+        return {name: "Some stream"};
-        }
-        throw new Error(`Unknown stream ${arg}`);
     });
 
     let count = unread.num_unread_for_topic(stream_id, "lunch");

frontend_tests/node_tests/upgrade.js

@@ -63,6 +63,7 @@ run_test("initialize", ({override_rewire}) => {
                     };
                     success_callback();
                     break;
+                /* istanbul ignore next */
                 default:
                     throw new Error("Unhandled case");
             }
@@ -85,9 +86,6 @@ run_test("initialize", ({override_rewire}) => {
     $("input[type=radio][name=schedule]:checked").val = () =>
         document.querySelector("input[type=radio][name=schedule]:checked").value;
 
-    $("#autopay-form").data = (key) =>
-        document.querySelector("#autopay-form").getAttribute("data-" + key);
-
     const initialize_function = $.get_initialize_function();
     initialize_function();
 

frontend_tests/node_tests/vdom.js

@@ -175,6 +175,7 @@ run_test("partial updates", () => {
 
     assert.equal(rendered_html, "<ul>\n<li>foo1</li>\n<li>foo2</li>\n<li>foo3</li>\n</ul>");
 
+    /* istanbul ignore next */
     replace_content = () => {
         throw new Error("should not replace entire html");
     };
@@ -209,6 +210,7 @@ run_test("partial updates", () => {
 });
 
 run_test("eq_array easy cases", () => {
+    /* istanbul ignore next */
     const bogus_eq = () => {
         throw new Error("we should not be comparing elements");
     };

frontend_tests/zjsunit/i18n.js

@@ -12,6 +12,7 @@ exports.intl = createIntl(
         defaultRichTextElements: Object.fromEntries(
             ["b", "code", "em", "i", "kbd", "p", "strong"].map((tag) => [
                 tag,
+                /* istanbul ignore next */
                 (content_html) => `<${tag}>${content_html}</${tag}>`,
             ]),
         ),

frontend_tests/zjsunit/index.js

@@ -1,5 +1,6 @@
 "use strict";
 
+const {strict: assert} = require("assert");
 const path = require("path");
 
 require("css.escape");
@@ -39,9 +40,7 @@ function immediate(f) {
 
 // Find the files we need to run.
 const files = process.argv.slice(2);
-if (files.length === 0) {
+assert.notEqual(files.length, 0, "No tests found");
-    throw new Error("No tests found");
-}
 
 // Set up our namespace helpers.
 const window = new Proxy(global, {
@@ -73,6 +72,7 @@ handlebars.hook_require();
 
 const noop = function () {};
 
+/* istanbul ignore next */
 function short_tb(tb) {
     const lines = tb.split("\n");
 
@@ -102,7 +102,6 @@ try {
     for (const file of files) {
         namespace.start();
         namespace.set_global("window", window);
-        namespace.set_global("to_$", () => window);
         namespace.set_global("location", dom.window.location);
         window.location.href = "http://zulip.zulipdev.com/#";
         namespace.set_global("setTimeout", noop);
@@ -132,7 +131,7 @@ try {
 
         namespace.finish();
     }
-} catch (error) {
+} catch (error) /* istanbul ignore next */ {
     if (process.env.USING_INSTRUMENTED_CODE) {
         console.info(`
     TEST FAILED! Before using the --coverage option please make sure that your

frontend_tests/zjsunit/markdown_assert.js

@@ -36,6 +36,7 @@ class MarkdownComparer {
     constructor(output_formatter) {
         this._output_formatter =
             output_formatter ||
+            /* istanbul ignore next */
             function (actual, expected) {
                 return ["Actual and expected output do not match.", actual, "!=", expected].join(
                     "\n",
@@ -44,6 +45,7 @@ class MarkdownComparer {
         this._document = new JSDOM().window.document;
     }
 
+    /* istanbul ignore next */
     setFormatter(output_formatter) {
         this._output_formatter = output_formatter || this._output_formatter;
     }
@@ -88,6 +90,7 @@ class MarkdownComparer {
             } else if (name_a > name_b) {
                 return 1;
             }
+            /* istanbul ignore next */
             return 0;
         });
 
@@ -139,6 +142,7 @@ class MarkdownComparer {
         message = message || "";
         message += "\n";
 
+        /* istanbul ignore if */
         if (comparison_results.are_equivalent === false) {
             throw new assert.AssertionError({
                 message:
@@ -157,6 +161,7 @@ class MarkdownComparer {
         message = message || "";
         message += "\n";
 
+        /* istanbul ignore if */
         if (comparison_results.are_equivalent) {
             throw new assert.AssertionError({
                 message:
@@ -174,11 +179,13 @@ class MarkdownComparer {
 
 function returnComparer() {
     if (!_markdownComparerInstance) {
-        _markdownComparerInstance = new MarkdownComparer((actual, expected) =>
+        _markdownComparerInstance = new MarkdownComparer(
-            [
+            /* istanbul ignore next */
-                "Actual and expected output do not match.  Showing diff",
+            (actual, expected) =>
-                mdiff.diff_strings(actual, expected),
+                [
-            ].join("\n"),
+                    "Actual and expected output do not match.  Showing diff",
+                    mdiff.diff_strings(actual, expected),
+                ].join("\n"),
         );
     }
     return _markdownComparerInstance;
@@ -193,6 +200,7 @@ module.exports = {
         returnComparer().assertNotEqual(actual, expected, message);
     },
 
+    /* istanbul ignore next */
     setFormatter(output_formatter) {
         returnComparer().setFormatter(output_formatter);
     },

frontend_tests/zjsunit/namespace.js

@@ -1,5 +1,6 @@
 "use strict";
 
+const {strict: assert} = require("assert");
 const Module = require("module");
 const path = require("path");
 
@@ -24,6 +25,7 @@ let jquery_function;
 
 const template_path = "/static/templates/";
 
+/* istanbul ignore next */
 function need_to_mock_template_error(filename) {
     const i = filename.indexOf(template_path);
 
@@ -100,6 +102,7 @@ function template_stub({filename, actual_render}) {
 
         // Force devs to call mock_template on every top-level template
         // render so they can introspect the data.
+        /* istanbul ignore if */
         if (!template_mocks.has(filename)) {
             throw new Error(need_to_mock_template_error(filename));
         }
@@ -126,9 +129,7 @@ function template_stub({filename, actual_render}) {
 }
 
 exports.start = () => {
-    if (actual_load !== undefined) {
+    assert.equal(actual_load, undefined, "namespace.start was called twice in a row.");
-        throw new Error("namespace.start was called twice in a row.");
-    }
     actual_load = Module._load;
     Module._load = load;
 };
@@ -163,11 +164,11 @@ exports.start = () => {
 // format preferred by Webpack.
 
 exports.mock_cjs = (module_path, obj) => {
-    if (module_path === "jquery") {
+    assert.notEqual(
-        throw new Error(
+        module_path,
-            "We automatically mock jquery to zjquery. Grep for mock_jquery if you want more control.",
+        "jquery",
-        );
+        "We automatically mock jquery to zjquery. Grep for mock_jquery if you want more control.",
-    }
+    );
 
     const filename = Module._resolveFilename(
         module_path,
@@ -175,13 +176,12 @@ exports.mock_cjs = (module_path, obj) => {
         false,
     );
 
-    if (module_mocks.has(filename)) {
+    assert.ok(!module_mocks.has(filename), `You already set up a mock for ${filename}`);
-        throw new Error(`You already set up a mock for ${filename}`);
-    }
 
-    if (filename in require.cache) {
+    assert.ok(
-        throw new Error(`It is too late to mock ${filename}; call this earlier.`);
+        !(filename in require.cache),
-    }
+        `It is too late to mock ${filename}; call this earlier.`,
+    );
 
     module_mocks.set(filename, obj);
     return obj;
@@ -199,11 +199,10 @@ exports._start_template_mocking = () => {
 
 exports._finish_template_mocking = () => {
     for (const filename of template_mocks.keys()) {
-        if (!used_templates.has(filename)) {
+        assert.ok(
-            throw new Error(
+            used_templates.has(filename),
-                `You called mock_template with ${filename} but we never saw it get used.`,
+            `You called mock_template with ${filename} but we never saw it get used.`,
-            );
+        );
-        }
     }
     template_mocks.clear();
     used_templates.clear();
@@ -222,9 +221,7 @@ exports._mock_template = (fn, exercise_template, f) => {
 };
 
 exports.mock_esm = (module_path, obj = {}) => {
-    if (typeof obj !== "object") {
+    assert.equal(typeof obj, "object", "An ES module must be mocked with an object");
-        throw new TypeError("An ES module must be mocked with an object");
-    }
     return exports.mock_cjs(module_path, {...obj, __esModule: true});
 };
 
@@ -235,24 +232,19 @@ exports.unmock_module = (module_path) => {
         false,
     );
 
-    if (!module_mocks.has(filename)) {
+    assert.ok(module_mocks.has(filename), `Cannot unmock ${filename}, which was not mocked`);
-        throw new Error(`Cannot unmock ${filename}, which was not mocked`);
-    }
 
-    if (!used_module_mocks.has(filename)) {
+    assert.ok(
-        throw new Error(`You asked to mock ${filename} but we never saw it during compilation.`);
+        used_module_mocks.has(filename),
-    }
+        `You asked to mock ${filename} but we never saw it during compilation.`,
+    );
 
     module_mocks.delete(filename);
     used_module_mocks.delete(filename);
 };
 
 exports.set_global = function (name, val) {
-    if (val === null) {
+    assert.notEqual(val, null, `We try to avoid using null in our codebase.`);
-        throw new Error(`
-            We try to avoid using null in our codebase.
-        `);
-    }
 
     if (!(name in old_globals)) {
         if (!(name in global)) {
@@ -265,14 +257,16 @@ exports.set_global = function (name, val) {
 };
 
 exports.zrequire = function (short_fn) {
-    if (short_fn === "templates") {
+    assert.notEqual(
-        throw new Error(`
+        short_fn,
+        "templates",
+        `
             There is no need to zrequire templates.js.
 
             The test runner automatically registers the
             Handlebar extensions.
-        `);
+        `,
-    }
+    );
 
     return require(`../../static/js/${short_fn}`);
 };
@@ -281,6 +275,7 @@ const staticPath = path.resolve(__dirname, "../../static") + path.sep;
 
 exports.complain_about_unused_mocks = function () {
     for (const filename of module_mocks.keys()) {
+        /* istanbul ignore if */
         if (!used_module_mocks.has(filename)) {
             console.error(`You asked to mock ${filename} but we never saw it during compilation.`);
         }
@@ -298,9 +293,7 @@ exports.finish = function () {
     */
     jquery_function = undefined;
 
-    if (actual_load === undefined) {
+    assert.notEqual(actual_load, undefined, "namespace.finish was called without namespace.start.");
-        throw new Error("namespace.finish was called without namespace.start.");
-    }
     Module._load = actual_load;
     actual_load = undefined;
 
@@ -321,11 +314,10 @@ exports.finish = function () {
 };
 
 exports.with_field = function (obj, field, val, f) {
-    if ("__esModule" in obj && "__Rewire__" in obj) {
+    assert.ok(
-        throw new TypeError(
+        !("__esModule" in obj && "__Rewire__" in obj),
-            "Cannot mutate an ES module from outside. Consider exporting a test helper function from it instead.",
+        "Cannot mutate an ES module from outside. Consider exporting a test helper function from it instead.",
-        );
+    );
-    }
 
     const had_val = Object.hasOwn(obj, field);
     const old_val = obj[field];
@@ -350,9 +342,11 @@ exports.with_field_rewire = function (obj, field, val, f) {
     // https://github.com/rosswarren/babel-plugin-rewire-ts/issues/15
     const old_val = field in obj ? obj[field] : obj.__GetDependency__(field);
 
-    if (typeof old_val === "function") {
+    assert.notEqual(
-        throw new TypeError("Please try to avoid mocking here, or use override_rewire.");
+        typeof old_val,
-    }
+        "function",
+        "Please try to avoid mocking here, or use override_rewire.",
+    );
 
     try {
         obj.__Rewire__(field, val);
@@ -369,14 +363,16 @@ exports.with_function_call_disallowed_rewire = function (obj, field, f) {
     // https://github.com/rosswarren/babel-plugin-rewire-ts/issues/15
     const old_val = field in obj ? obj[field] : obj.__GetDependency__(field);
 
-    if (typeof old_val !== "function") {
+    assert.equal(typeof old_val, "function", `Expected a function for ${field}`);
-        throw new TypeError(`Expected a function for ${field}`);
-    }
 
     try {
-        obj.__Rewire__(field, () => {
+        obj.__Rewire__(
-            throw new Error(`unexpected call to ${field}`);
+            field,
-        });
+            /* istanbul ignore next */
+            () => {
+                throw new Error(`unexpected call to ${field}`);
+            },
+        );
         return f();
     } finally {
         obj.__Rewire__(field, old_val);
@@ -397,28 +393,29 @@ exports.with_overrides = function (test_function) {
         // step.  Generally our code calls `run_test`, which wraps
         // `with_overrides`.
 
-        if ("__esModule" in obj && "__Rewire__" in obj) {
+        assert.ok(
-            throw new TypeError(
+            !("__esModule" in obj && "__Rewire__" in obj),
-                "Cannot mutate an ES module from outside. Consider exporting a test helper function from it instead.",
+            "Cannot mutate an ES module from outside. Consider exporting a test helper function from it instead.",
-            );
+        );
-        }
 
-        if (typeof f !== "function") {
+        assert.equal(
-            throw new TypeError(
+            typeof f,
-                "You can only override with a function. Use with_field for non-functions.",
+            "function",
-            );
+            "You can only override with a function. Use with_field for non-functions.",
-        }
+        );
 
-        if (typeof obj !== "object" && typeof obj !== "function") {
+        assert.ok(
-            throw new TypeError(`We cannot override a function for ${typeof obj} objects`);
+            typeof obj === "object" || typeof obj === "function",
-        }
+            `We cannot override a function for ${typeof obj} objects`,
+        );
 
-        if (obj[func_name] !== undefined && typeof obj[func_name] !== "function") {
+        assert.ok(
-            throw new TypeError(`
+            obj[func_name] === undefined || typeof obj[func_name] === "function",
+            `
                 You are overriding a non-function with a function.
                 This is almost certainly an error.
-            `);
+            `,
-        }
+        );
 
         if (!unused_funcs.has(obj)) {
             unused_funcs.set(obj, new Map());
@@ -449,22 +446,24 @@ exports.with_overrides = function (test_function) {
         // as exporting a helper function for tests from the module
         // containing the function you need to mock.
 
-        if (typeof f !== "function") {
+        assert.equal(
-            throw new TypeError(
+            typeof f,
-                "You can only override with a function. Use with_field for non-functions.",
+            "function",
-            );
+            "You can only override with a function. Use with_field for non-functions.",
-        }
+        );
 
-        if (typeof obj !== "object" && typeof obj !== "function") {
+        assert.ok(
-            throw new TypeError(`We cannot override a function for ${typeof obj} objects`);
+            typeof obj === "object" || typeof obj === "function",
-        }
+            `We cannot override a function for ${typeof obj} objects`,
+        );
 
-        if (obj[func_name] !== undefined && typeof obj[func_name] !== "function") {
+        assert.ok(
-            throw new TypeError(`
+            obj[func_name] === undefined || typeof obj[func_name] === "function",
+            `
                 You are overriding a non-function with a function.
                 This is almost certainly an error.
-            `);
+            `,
-        }
+        );
 
         if (!unused_funcs.has(obj)) {
             unused_funcs.set(obj, new Map());
@@ -497,6 +496,7 @@ exports.with_overrides = function (test_function) {
 
     for (const module_unused_funcs of unused_funcs.values()) {
         for (const unused_name of module_unused_funcs.keys()) {
+            /* istanbul ignore next */
             throw new Error(unused_name + " never got invoked!");
         }
     }

frontend_tests/zjsunit/test.js

@@ -19,6 +19,7 @@ exports.set_verbose = (value) => {
 exports.run_test = (label, f, opts) => {
     const {sloppy_$} = opts || {};
 
+    /* istanbul ignore if */
     if (verbose) {
         console.info("        test: " + label);
     }
@@ -34,7 +35,7 @@ exports.run_test = (label, f, opts) => {
             f({override, override_rewire, mock_template: namespace._mock_template});
         });
         namespace._finish_template_mocking();
-    } catch (error) {
+    } catch (error) /* istanbul ignore next */ {
         console.info("-".repeat(50));
         console.info(`test failed: ${current_file_name} > ${label}`);
         console.info();

frontend_tests/zjsunit/zblueslip.js

@@ -1,5 +1,7 @@
 "use strict";
 
+const {strict: assert} = require("assert");
+
 function make_zblueslip() {
     const lib = {};
 
@@ -15,6 +17,7 @@ function make_zblueslip() {
     const names = Array.from(Object.keys(opts));
 
     // For fatal messages, we should use assert.throws
+    /* istanbul ignore next */
     lib.fatal = (msg) => {
         throw new Error(msg);
     };
@@ -28,14 +31,13 @@ function make_zblueslip() {
         lib.test_logs[name] = [];
     }
 
-    lib.expect = (name, message, count = 1) => {
+    lib.expect = (name, message, expected_count = 1) => {
-        if (opts[name] === undefined) {
+        assert.notEqual(opts[name], undefined, `unexpected arg for expect: ${name}`);
-            throw new Error("unexpected arg for expect: " + name);
+        assert.ok(
-        }
+            expected_count > 0 && Number.isInteger(expected_count),
-        if (count <= 0 && Number.isInteger(count)) {
+            "expected count should be a positive integer",
-            throw new Error("expected count should be a positive integer");
+        );
-        }
+        const obj = {message, count: 0, expected_count};
-        const obj = {message, count, expected_count: count};
         lib.test_data[name].push(obj);
     };
 
@@ -52,22 +54,16 @@ function make_zblueslip() {
                     }
                     continue;
                 }
-                lib.test_data[name][i].count -= 1;
+                lib.test_data[name][i].count += 1;
             }
 
             for (const obj of lib.test_data[name]) {
                 const message = obj.message;
-                if (obj.count > 0) {
+                assert.equal(
-                    throw new Error(
+                    obj.count,
-                        `We did not see expected ${obj.expected_count} of '${name}': ${message}`,
+                    obj.expected_count,
-                    );
+                    `Expected ${obj.expected_count} of '${name}': ${message}`,
-                } else if (obj.count < 0) {
+                );
-                    throw new Error(
-                        `We saw ${obj.expected_count - obj.count} (expected ${
-                            obj.expected_count
-                        }) of '${name}': ${message}`,
-                    );
-                }
             }
         }
     };
@@ -95,6 +91,7 @@ function make_zblueslip() {
             continue;
         }
         lib[name] = function (message, more_info, stack) {
+            /* istanbul ignore if */
             if (typeof message !== "string") {
                 // We may catch exceptions in blueslip, and if
                 // so our stub should include that.
@@ -121,6 +118,7 @@ function make_zblueslip() {
 
     lib.measure_time = (label, f) => f();
 
+    /* istanbul ignore next */
     lib.preview_node = (node) => "node:" + node;
 
     return lib;

frontend_tests/zjsunit/zjquery.js

@@ -23,16 +23,15 @@ function verify_selector_for_zulip(selector) {
         selector.includes(".") ||
         (selector.includes("[") && selector.indexOf("]") >= selector.indexOf("["));
 
-    if (!is_valid) {
+    assert.ok(
+        is_valid,
         // Check if selector has only english alphabets and space.
         // Then, the user is probably trying to use a tag as a selector
         // like $('div a').
-        if (/^[ A-Za-z]+$/.test(selector)) {
+        /^[ A-Za-z]+$/.test(selector)
-            throw new Error("Selector too broad! Use id, class or attributes of target instead.");
+            ? "Selector too broad! Use id, class or attributes of target instead."
-        } else {
+            : `Invalid selector: ${selector}. Use $.create() maybe?`,
-            throw new Error("Invalid selector: " + selector + " Use $.create() maybe?");
+    );
-        }
-    }
 }
 
 function make_zjquery() {
@@ -56,15 +55,16 @@ function make_zjquery() {
                 // Handle the special case of equality checks, which
                 // we can infer by assert.equal trying to access the
                 // "stack" key.
-                if (key === "stack") {
+                assert.notEqual(
-                    const error =
+                    key,
-                        "\nInstead of doing equality checks on a full object, " +
+                    "stack",
-                        'do `assert_equal($foo.selector, ".some_class")\n';
+                    "\nInstead of doing equality checks on a full object, " +
-                    throw new Error(error);
+                        'do `assert.equal($foo.selector, ".some_class")\n',
-                }
+                );
 
                 const val = target[key];
 
+                /* istanbul ignore if */
                 if (val === undefined && typeof key !== "symbol" && key !== "inspect") {
                     // For undefined values, we'll throw errors to devs saying
                     // they need to create stubs.  We ignore certain keys that
@@ -85,16 +85,17 @@ function make_zjquery() {
 
     const zjquery = function (arg, arg2) {
         if (typeof arg === "function") {
-            if (initialize_function) {
+            assert.ok(
-                throw new Error(`
+                !initialize_function,
+                `
                     We are trying to avoid the $(...) mechanism
                     for initializing modules in our codebase,
                     and the code that you are compiling/running
                     has tried to do this twice.  Please either
                     clean up the real code or reduce the scope
                     of what you are testing in this test module.
-                `);
+                `,
-            }
+            );
             initialize_function = arg;
             return undefined;
         }
@@ -116,12 +117,15 @@ function make_zjquery() {
             return arg.to_$();
         }
 
-        if (arg2 !== undefined) {
+        assert.equal(
-            throw new Error("We only use one-argument variations of $(...) in Zulip code.");
+            arg2,
-        }
+            undefined,
+            "We only use one-argument variations of $(...) in Zulip code.",
+        );
 
         const selector = arg;
 
+        /* istanbul ignore if */
         if (typeof selector !== "string") {
             console.info(arg);
             throw new Error("zjquery does not know how to wrap this object yet");
@@ -152,10 +156,7 @@ function make_zjquery() {
         return $elem;
     };
 
-    zjquery.trim = function (s) {
+    /* istanbul ignore next */
-        return s;
-    };
-
     zjquery.state = function () {
         // useful for debugging
         let res = Array.from(elems.values(), ($v) => $v.debug());
@@ -169,6 +170,7 @@ function make_zjquery() {
 
     zjquery.Event = FakeEvent;
 
+    /* istanbul ignore next */
     fn.popover = () => {
         throw new Error(`
             Do not try to test $.fn.popover code unless
@@ -186,6 +188,7 @@ function make_zjquery() {
                 return true;
             }
 
+            /* istanbul ignore next */
             throw new Error(`
                 Please don't use node tests to test code
                 that extends $.fn unless you really know
@@ -209,6 +212,7 @@ function make_zjquery() {
     };
 
     zjquery.validator = {
+        /* istanbul ignore next */
         addMethod() {
             throw new Error("You must create your own $.validator.addMethod stub.");
         },
@@ -229,6 +233,7 @@ const $ = new Proxy(make_zjquery(), {
             return true;
         }
 
+        /* istanbul ignore next */
         throw new Error(`
             Please don't modify $.${prop} if you are using zjquery.
 

frontend_tests/zjsunit/zjquery_element.js

@@ -48,6 +48,7 @@ function FakeElement(selector, opts) {
         delay() {
             return $self;
         },
+        /* istanbul ignore next */
         debug() {
             return {
                 value,
@@ -61,9 +62,6 @@ function FakeElement(selector, opts) {
             }
             return $self;
         },
-        eq() {
-            return $self;
-        },
         expectOne() {
             // silently do nothing
             return $self;
@@ -80,6 +78,7 @@ function FakeElement(selector, opts) {
                 // if ($.find().length) { //success }
                 return [];
             }
+            /* istanbul ignore next */
             throw new Error(`
                 We need you to simulate the results of $(...).find(...)
                 by using set_find_results. You want something like this:
@@ -100,9 +99,7 @@ function FakeElement(selector, opts) {
             return classes.has(class_name);
         },
         height() {
-            if (height === undefined) {
+            assert.notEqual(height, undefined, `Please call $("${selector}").set_height`);
-                throw new Error(`Please call $("${selector}").set_height`);
-            }
             return height;
         },
         hide() {
@@ -117,13 +114,15 @@ function FakeElement(selector, opts) {
             return html;
         },
         is(arg) {
-            if (arg === ":visible") {
+            switch (arg) {
-                return shown;
+                case ":visible":
+                    return shown;
+                case ":focus":
+                    return $self.is_focused();
+                /* istanbul ignore next */
+                default:
+                    throw new Error("zjquery does not support this is() call");
             }
-            if (arg === ":focus") {
-                return $self.is_focused();
-            }
-            return $self;
         },
         is_focused() {
             // is_focused is not a jQuery thing; this is
@@ -144,6 +143,7 @@ function FakeElement(selector, opts) {
             event_store.on(...args);
             return $self;
         },
+        /* istanbul ignore next */
         one(...args) {
             event_store.one(...args);
             return $self;
@@ -181,6 +181,7 @@ function FakeElement(selector, opts) {
             }
             return $self;
         },
+        /* istanbul ignore next */
         remove() {
             throw new Error(`
                 We don't support remove in zjquery.
@@ -192,21 +193,12 @@ function FakeElement(selector, opts) {
             `);
         },
         removeData: noop,
-        replaceWith() {
-            return $self;
-        },
-        scrollTop() {
-            return $self;
-        },
-        serializeArray() {
-            return $self;
-        },
         set_find_results(find_selector, $jquery_object) {
-            if ($jquery_object === undefined) {
+            assert.notEqual(
-                throw new Error(
+                $jquery_object,
-                    "Please make the 'find result' be something like $.create('unused')",
+                undefined,
-                );
+                "Please make the 'find result' be something like $.create('unused')",
-            }
+            );
             find_results.set(find_selector, $jquery_object);
         },
         set_height(fake_height) {
@@ -222,9 +214,6 @@ function FakeElement(selector, opts) {
             shown = true;
             return $self;
         },
-        slice() {
-            return $self;
-        },
         stop() {
             return $self;
         },
@@ -242,9 +231,6 @@ function FakeElement(selector, opts) {
             shown = show;
             return $self;
         },
-        tooltip() {
-            return $self;
-        },
         trigger(ev) {
             event_store.trigger($self, ev);
             return $self;
@@ -314,9 +300,7 @@ function make_event_store(selector) {
 
             if (child_selector === undefined) {
                 handler = on_functions.get(name);
-                if (!handler) {
+                assert.ok(handler, `no ${name} handler for ${selector}`);
-                    throw new Error("no " + name + " handler for " + selector);
-                }
                 return handler;
             }
 
@@ -325,9 +309,7 @@ function make_event_store(selector) {
                 handler = child_on.get(name);
             }
 
-            if (!handler) {
+            assert.ok(handler, `no ${name} handler for ${selector} ${child_selector}`);
-                throw new Error("no " + name + " handler for " + selector + " " + child_selector);
-            }
 
             return handler;
         },
@@ -342,6 +324,7 @@ function make_event_store(selector) {
             // .off in code that we test: $(...).off('click', child_sel);
             //
             // So we don't support this for now.
+            /* istanbul ignore next */
             throw new Error("zjquery does not support this call sequence");
         },
 
@@ -351,6 +334,7 @@ function make_event_store(selector) {
             //    (event_name, sel, handler)
             if (args.length === 1) {
                 const [handler] = args;
+                /* istanbul ignore if */
                 if (on_functions.has(event_name)) {
                     console.info("\nEither the app or the test can be at fault here..");
                     console.info("(sometimes you just want to call $.clear_all_elements();)\n");
@@ -361,9 +345,7 @@ function make_event_store(selector) {
                 return;
             }
 
-            if (args.length !== 2) {
+            assert.equal(args.length, 2, "wrong number of arguments passed in");
-                throw new Error("wrong number of arguments passed in");
-            }
 
             const [sel, handler] = args;
             assert.equal(typeof sel, "string", "String selectors expected here.");
@@ -375,13 +357,15 @@ function make_event_store(selector) {
 
             const child_on = child_on_functions.get(sel);
 
-            if (child_on.has(event_name)) {
+            assert.ok(
-                throw new Error("dup " + event_name + " handler for " + selector + " " + sel);
+                !child_on.has(event_name),
-            }
+                `dup ${event_name} handler for ${selector} ${sel}`,
+            );
 
             child_on.set(event_name, handler);
         },
 
+        /* istanbul ignore next */
         one(event_name, handler) {
             self.on(event_name, function (ev) {
                 self.off(event_name);

frontend_tests/zjsunit/zjquery_event.js

@@ -2,9 +2,6 @@
 
 class FakeEvent {
     constructor(type, props) {
-        if (!(this instanceof FakeEvent)) {
-            return new FakeEvent(type, props);
-        }
         this.type = type;
         Object.assign(this, props);
     }

tools/test-js-with-node

@@ -44,6 +44,8 @@ def make_set(files: List[str]) -> Set[str]:
 # We do not yet require 100% line coverage for these files:
 EXEMPT_FILES = make_set(
     [
+        "frontend_tests/node_tests/event_status.js",
+        "frontend_tests/zjsunit/mdiff.js",
         "static/js/about_zulip.js",
         "static/js/add_subscribers_pill.js",
         "static/js/admin.js",
@@ -372,14 +374,16 @@ def read_coverage() -> Any:
 
 
 def enforce_proper_coverage(coverage_json: Any) -> bool:
-    all_js_files = set(
+    all_js_files = {
-        glob.glob("static/js/*.js")
+        *glob.glob("frontend_tests/node_tests/*.js"),
-        + glob.glob("static/js/*.ts")
+        *glob.glob("frontend_tests/zjsunit/*.js"),
-        + glob.glob("static/shared/js/*.js")
+        *glob.glob("static/js/*.js"),
-        + glob.glob("static/shared/js/*.ts")
+        *glob.glob("static/js/*.ts"),
-        + glob.glob("static/js/billing/*.js"),
+        *glob.glob("static/shared/js/*.js"),
-    )
+        *glob.glob("static/shared/js/*.ts"),
-    enforce_fully_covered = all_js_files - EXEMPT_FILES
+        *glob.glob("static/js/billing/*.js"),
+    }
+    enforce_fully_covered = sorted(all_js_files - EXEMPT_FILES)
 
     coverage_lost = False
     for relative_path in enforce_fully_covered: