LibJS: Implement Temporal.PlainYearMonth.prototype.equals

Author: https://github.com/Lubrsi
Commit: https://github.com/SerenityOS/serenity/commit/58e2597dc2e
Pull-request: https://github.com/SerenityOS/serenity/pull/9907
Reviewed-by: https://github.com/IdanHo ✅
Reviewed-by: https://github.com/linusg ✅

Userland/Libraries/LibJS/Runtime/Temporal/PlainYearMonthPrototype.cpp

@@ -40,6 +40,7 @@ void PlainYearMonthPrototype::initialize(GlobalObject& global_object)
     define_native_accessor(vm.names.eraYear, era_year_getter, {}, Attribute::Configurable);
 
     u8 attr = Attribute::Writable | Attribute::Configurable;
+    define_native_function(vm.names.equals, equals, 1, attr);
     define_native_function(vm.names.toString, to_string, 0, attr);
     define_native_function(vm.names.toLocaleString, to_locale_string, 0, attr);
     define_native_function(vm.names.toJSON, to_json, 0, attr);
@@ -217,6 +218,36 @@ JS_DEFINE_NATIVE_FUNCTION(PlainYearMonthPrototype::era_year_getter)
     return calendar_era_year(global_object, calendar, *plain_year_month);
 }
 
+// 9.3.16 Temporal.PlainYearMonth.prototype.equals ( other ), https://tc39.es/proposal-temporal/#sec-temporal.plainyearmonth.prototype.equals
+JS_DEFINE_NATIVE_FUNCTION(PlainYearMonthPrototype::equals)
+{
+    // 1. Let yearMonth be the this value.
+    // 2. Perform ? RequireInternalSlot(yearMonth, [[InitializedTemporalYearMonth]]).
+    auto* year_month = typed_this(global_object);
+    if (vm.exception())
+        return {};
+
+    // 3. Set other to ? ToTemporalYearMonth(other).
+    auto* other = to_temporal_year_month(global_object, vm.argument(0));
+    if (vm.exception())
+        return {};
+
+    // 4. If yearMonth.[[ISOYear]] ≠ other.[[ISOYear]], return false.
+    if (year_month->iso_year() != other->iso_year())
+        return Value(false);
+
+    // 5. If yearMonth.[[ISOMonth]] ≠ other.[[ISOMonth]], return false.
+    if (year_month->iso_month() != other->iso_month())
+        return Value(false);
+
+    // 6. If yearMonth.[[ISODay]] ≠ other.[[ISODay]], return false.
+    if (year_month->iso_day() != other->iso_day())
+        return Value(false);
+
+    // 7. Return ? CalendarEquals(yearMonth.[[Calendar]], other.[[Calendar]]).
+    return Value(calendar_equals(global_object, year_month->calendar(), other->calendar()));
+}
+
 // 9.3.17 Temporal.PlainYearMonth.prototype.toString ( [ options ] ), https://tc39.es/proposal-temporal/#sec-temporal.plainyearmonth.prototype.tostring
 JS_DEFINE_NATIVE_FUNCTION(PlainYearMonthPrototype::to_string)
 {

Userland/Libraries/LibJS/Runtime/Temporal/PlainYearMonthPrototype.h

@@ -29,6 +29,7 @@ private:
     JS_DECLARE_NATIVE_FUNCTION(in_leap_year_getter);
     JS_DECLARE_NATIVE_FUNCTION(era_getter);
     JS_DECLARE_NATIVE_FUNCTION(era_year_getter);
+    JS_DECLARE_NATIVE_FUNCTION(equals);
     JS_DECLARE_NATIVE_FUNCTION(to_string);
     JS_DECLARE_NATIVE_FUNCTION(to_locale_string);
     JS_DECLARE_NATIVE_FUNCTION(to_json);

Userland/Libraries/LibJS/Tests/builtins/Temporal/PlainYearMonth/PlainYearMonth.prototype.equals.js

@@ -0,0 +1,15 @@
+describe("correct behavior", () => {
+    test("length is 1", () => {
+        expect(Temporal.PlainYearMonth.prototype.equals).toHaveLength(1);
+    });
+
+    test("basic functionality", () => {
+        const calendar = { hello: "friends" };
+        const firstPlainDateTime = new Temporal.PlainYearMonth(1, 1, calendar);
+        const secondPlainDateTime = new Temporal.PlainYearMonth(0, 1, calendar);
+        expect(firstPlainDateTime.equals(firstPlainDateTime)).toBeTrue();
+        expect(secondPlainDateTime.equals(secondPlainDateTime)).toBeTrue();
+        expect(firstPlainDateTime.equals(secondPlainDateTime)).toBeFalse();
+        expect(secondPlainDateTime.equals(firstPlainDateTime)).toBeFalse();
+    });
+});