LibJS: Implement Temporal.PlainYearMonth.prototype.monthCode

3 files changed, 32 insertions, 0 deletions

diff --git a/Userland/Libraries/LibJS/Runtime/Temporal/PlainYearMonthPrototype.cpp b/Userland/Libraries/LibJS/Runtime/Temporal/PlainYearMonthPrototype.cpp
index d6151d6775..5f473c13c8 100644
--- a/Userland/Libraries/LibJS/Runtime/Temporal/PlainYearMonthPrototype.cpp
+++ b/Userland/Libraries/LibJS/Runtime/Temporal/PlainYearMonthPrototype.cpp
@@ -30,6 +30,7 @@ void PlainYearMonthPrototype::initialize(GlobalObject& global_object)
     define_native_accessor(vm.names.calendar, calendar_getter, {}, Attribute::Configurable);
     define_native_accessor(vm.names.year, year_getter, {}, Attribute::Configurable);
     define_native_accessor(vm.names.month, month_getter, {}, Attribute::Configurable);
+    define_native_accessor(vm.names.monthCode, month_code_getter, {}, Attribute::Configurable);
 }
 
 static PlainYearMonth* typed_this(GlobalObject& global_object)
@@ -90,4 +91,20 @@ JS_DEFINE_NATIVE_FUNCTION(PlainYearMonthPrototype::month_getter)
     return Value(calendar_month(global_object, calendar, *year_month));
 }
 
+// 9.3.6 get Temporal.PlainYearMonth.prototype.monthCode, https://tc39.es/proposal-temporal/#sec-get-temporal.plainyearmonth.prototype.monthCode
+JS_DEFINE_NATIVE_FUNCTION(PlainYearMonthPrototype::month_code_getter)
+{
+    // 1. Let yearMonth be the this value.
+    // 2. Perform ? RequireInternalSlot(yearMonth, [[InitializedTemporalYearMonth]]).
+    auto* year_month = typed_this(global_object);
+    if (vm.exception())
+        return {};
+
+    // 3. Let calendar be yearMonth.[[Calendar]].
+    auto& calendar = year_month->calendar();
+
+    // 4. Return ? CalendarMonthCode(calendar, yearMonth).
+    return js_string(vm, calendar_month_code(global_object, calendar, *year_month));
+}
+
 }
diff --git a/Userland/Libraries/LibJS/Runtime/Temporal/PlainYearMonthPrototype.h b/Userland/Libraries/LibJS/Runtime/Temporal/PlainYearMonthPrototype.h
index 680ed8dd2d..5b9399a6c7 100644
--- a/Userland/Libraries/LibJS/Runtime/Temporal/PlainYearMonthPrototype.h
+++ b/Userland/Libraries/LibJS/Runtime/Temporal/PlainYearMonthPrototype.h
@@ -22,6 +22,7 @@ private:
     JS_DECLARE_NATIVE_FUNCTION(calendar_getter);
     JS_DECLARE_NATIVE_FUNCTION(year_getter);
     JS_DECLARE_NATIVE_FUNCTION(month_getter);
+    JS_DECLARE_NATIVE_FUNCTION(month_code_getter);
 };
 
 }
diff --git a/Userland/Libraries/LibJS/Tests/builtins/Temporal/PlainYearMonth/PlainYearMonth.prototype.monthCode.js b/Userland/Libraries/LibJS/Tests/builtins/Temporal/PlainYearMonth/PlainYearMonth.prototype.monthCode.js
new file mode 100644
index 0000000000..f2e5adb2f0
--- /dev/null
+++ b/Userland/Libraries/LibJS/Tests/builtins/Temporal/PlainYearMonth/PlainYearMonth.prototype.monthCode.js
@@ -0,0 +1,14 @@
+describe("correct behavior", () => {
+    test("basic functionality", () => {
+        const plainYearMonth = new Temporal.PlainYearMonth(2021, 7);
+        expect(plainYearMonth.monthCode).toBe("M07");
+    });
+});
+
+describe("errors", () => {
+    test("this value must be a Temporal.PlainYearMonth object", () => {
+        expect(() => {
+            Reflect.get(Temporal.PlainYearMonth.prototype, "monthCode", "foo");
+        }).toThrowWithMessage(TypeError, "Not a Temporal.PlainYearMonth");
+    });
+});