LibJS: Implement Date.prototype.setUTCHours

Author: https://github.com/trflynn89
Commit: https://github.com/SerenityOS/serenity/commit/51bc973eccc
Pull-request: https://github.com/SerenityOS/serenity/pull/11930
Reviewed-by: https://github.com/linusg ✅

Userland/Libraries/LibJS/Runtime/DatePrototype.cpp

@@ -74,7 +74,7 @@ void DatePrototype::initialize(GlobalObject& global_object)
     define_native_function(vm.names.setTime, set_time, 1, attr);
     define_native_function(vm.names.setUTCDate, set_date, 1, attr);          // FIXME: This is a hack, Serenity doesn't currently support timezones other than UTC.
     define_native_function(vm.names.setUTCFullYear, set_full_year, 3, attr); // FIXME: see above
-    define_native_function(vm.names.setUTCHours, set_hours, 4, attr);        // FIXME: see above
+    define_native_function(vm.names.setUTCHours, set_utc_hours, 4, attr);
     define_native_function(vm.names.setUTCMilliseconds, set_utc_milliseconds, 1, attr);
     define_native_function(vm.names.setUTCMinutes, set_utc_minutes, 3, attr);
     define_native_function(vm.names.setUTCMonth, set_utc_month, 2, attr);
@@ -619,6 +619,40 @@ JS_DEFINE_NATIVE_FUNCTION(DatePrototype::set_time)
     return time;
 }
 
+// 21.4.4.30 Date.prototype.setUTCHours ( hour [ , min [ , sec [ , ms ] ] ] ), https://tc39.es/ecma262/#sec-date.prototype.setutchours
+JS_DEFINE_NATIVE_FUNCTION(DatePrototype::set_utc_hours)
+{
+    // 1. Let t be LocalTime(? thisTimeValue(this value)).
+    auto this_time = TRY(this_time_value(global_object, vm.this_value(global_object)));
+    auto time = local_time(this_time.as_double());
+
+    // 2. Let h be ? ToNumber(hour).
+    auto hour = TRY(vm.argument(0).to_number(global_object));
+
+    // 3. If min is not present, let m be MinFromTime(t); otherwise, let m be ? ToNumber(min).
+    auto minute = TRY(argument_or_value(global_object, 1, min_from_time(time)));
+
+    // 4. If sec is not present, let s be SecFromTime(t); otherwise, let s be ? ToNumber(sec).
+    auto second = TRY(argument_or_value(global_object, 2, sec_from_time(time)));
+
+    // 5. If ms is not present, let milli be msFromTime(t); otherwise, let milli be ? ToNumber(ms).
+    auto millisecond = TRY(argument_or_value(global_object, 3, ms_from_time(time)));
+
+    // 6. Let date be MakeDate(Day(t), MakeTime(h, m, s, milli)).
+    auto new_time = make_time(global_object, hour, minute, second, millisecond);
+    auto date = make_date(Value(day(time)), new_time);
+
+    // 7. Let v be TimeClip(newDate).
+    date = time_clip(global_object, date);
+
+    // 8. Set the [[DateValue]] internal slot of this Date object to v.
+    auto* this_object = MUST(typed_this_object(global_object));
+    this_object->set_date_value(date.as_double());
+
+    // 9. Return v.
+    return date;
+}
+
 // 21.4.4.31 Date.prototype.setUTCMilliseconds ( ms ), https://tc39.es/ecma262/#sec-date.prototype.setutcmilliseconds
 JS_DEFINE_NATIVE_FUNCTION(DatePrototype::set_utc_milliseconds)
 {

Userland/Libraries/LibJS/Runtime/DatePrototype.h

@@ -46,6 +46,7 @@ private:
     JS_DECLARE_NATIVE_FUNCTION(set_month);
     JS_DECLARE_NATIVE_FUNCTION(set_seconds);
     JS_DECLARE_NATIVE_FUNCTION(set_time);
+    JS_DECLARE_NATIVE_FUNCTION(set_utc_hours);
     JS_DECLARE_NATIVE_FUNCTION(set_utc_milliseconds);
     JS_DECLARE_NATIVE_FUNCTION(set_utc_minutes);
     JS_DECLARE_NATIVE_FUNCTION(set_utc_month);

Userland/Libraries/LibJS/Tests/builtins/Date/Date.prototype.setUTCHours.js

@@ -0,0 +1,65 @@
+describe("errors", () => {
+    test("called on non-Date object", () => {
+        expect(() => {
+            Date.prototype.setUTCHours();
+        }).toThrowWithMessage(TypeError, "Not an object of type Date");
+    });
+
+    test("called with non-numeric parameters", () => {
+        expect(() => {
+            new Date().setUTCHours(Symbol.hasInstance);
+        }).toThrowWithMessage(TypeError, "Cannot convert symbol to number");
+
+        expect(() => {
+            new Date().setUTCHours(8, Symbol.hasInstance);
+        }).toThrowWithMessage(TypeError, "Cannot convert symbol to number");
+
+        expect(() => {
+            new Date().setUTCHours(8, 9, Symbol.hasInstance);
+        }).toThrowWithMessage(TypeError, "Cannot convert symbol to number");
+
+        expect(() => {
+            new Date().setUTCHours(8, 9, 10, Symbol.hasInstance);
+        }).toThrowWithMessage(TypeError, "Cannot convert symbol to number");
+    });
+});
+
+describe("correct behavior", () => {
+    const d = new Date(2000, 2, 1);
+
+    test("basic functionality", () => {
+        d.setUTCHours(8);
+        expect(d.getUTCHours()).toBe(8);
+
+        d.setUTCHours(9, 15);
+        expect(d.getUTCHours()).toBe(9);
+        expect(d.getUTCMinutes()).toBe(15);
+
+        d.setUTCHours(10, 25, 35);
+        expect(d.getUTCHours()).toBe(10);
+        expect(d.getUTCMinutes()).toBe(25);
+        expect(d.getUTCSeconds()).toBe(35);
+
+        d.setUTCHours(11, 35, 45, 789);
+        expect(d.getUTCHours()).toBe(11);
+        expect(d.getUTCMinutes()).toBe(35);
+        expect(d.getUTCSeconds()).toBe(45);
+        expect(d.getUTCMilliseconds()).toBe(789);
+
+        d.setUTCHours("");
+        expect(d.getUTCHours()).toBe(0);
+
+        d.setUTCHours("a");
+        expect(d.getUTCHours()).toBe(NaN);
+    });
+
+    test("NaN", () => {
+        d.setUTCHours(NaN);
+        expect(d.getUTCHours()).toBeNaN();
+    });
+
+    test("time clip", () => {
+        d.setUTCHours(8.65e15);
+        expect(d.getUTCHours()).toBeNaN();
+    });
+});