From 1f1d7144bfdde258266b9f4aeab7e96ae5fc140c Mon Sep 17 00:00:00 2001
From: Linus Groh <mail@linusgroh.de>
Date: Sat, 7 Aug 2021 23:51:57 +0100
Subject: [PATCH] LibJS: Implement Temporal.PlainYearMonth.prototype.daysInYear

---
 .../Temporal/PlainYearMonthPrototype.cpp        | 17 +++++++++++++++++
 .../Runtime/Temporal/PlainYearMonthPrototype.h  |  1 +
 .../PlainYearMonth.prototype.daysInYear.js      | 14 ++++++++++++++
 3 files changed, 32 insertions(+)
 create mode 100644 Userland/Libraries/LibJS/Tests/builtins/Temporal/PlainYearMonth/PlainYearMonth.prototype.daysInYear.js

diff --git a/Userland/Libraries/LibJS/Runtime/Temporal/PlainYearMonthPrototype.cpp b/Userland/Libraries/LibJS/Runtime/Temporal/PlainYearMonthPrototype.cpp
index 5f473c13c8..1b0473b692 100644
--- a/Userland/Libraries/LibJS/Runtime/Temporal/PlainYearMonthPrototype.cpp
+++ b/Userland/Libraries/LibJS/Runtime/Temporal/PlainYearMonthPrototype.cpp
@@ -31,6 +31,7 @@ void PlainYearMonthPrototype::initialize(GlobalObject& global_object)
     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);
+    define_native_accessor(vm.names.daysInYear, days_in_year_getter, {}, Attribute::Configurable);
 }
 
 static PlainYearMonth* typed_this(GlobalObject& global_object)
@@ -107,4 +108,20 @@ JS_DEFINE_NATIVE_FUNCTION(PlainYearMonthPrototype::month_code_getter)
     return js_string(vm, calendar_month_code(global_object, calendar, *year_month));
 }
 
+// 9.3.7 get Temporal.PlainYearMonth.prototype.daysInYear, https://tc39.es/proposal-temporal/#sec-get-temporal.plainyearmonth.prototype.daysinyear
+JS_DEFINE_NATIVE_FUNCTION(PlainYearMonthPrototype::days_in_year_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 ? CalendarDaysInYear(calendar, yearMonth).
+    return Value(calendar_days_in_year(global_object, calendar, *year_month));
+}
+
 }
diff --git a/Userland/Libraries/LibJS/Runtime/Temporal/PlainYearMonthPrototype.h b/Userland/Libraries/LibJS/Runtime/Temporal/PlainYearMonthPrototype.h
index 5b9399a6c7..b556ab4277 100644
--- a/Userland/Libraries/LibJS/Runtime/Temporal/PlainYearMonthPrototype.h
+++ b/Userland/Libraries/LibJS/Runtime/Temporal/PlainYearMonthPrototype.h
@@ -23,6 +23,7 @@ private:
     JS_DECLARE_NATIVE_FUNCTION(year_getter);
     JS_DECLARE_NATIVE_FUNCTION(month_getter);
     JS_DECLARE_NATIVE_FUNCTION(month_code_getter);
+    JS_DECLARE_NATIVE_FUNCTION(days_in_year_getter);
 };
 
 }
diff --git a/Userland/Libraries/LibJS/Tests/builtins/Temporal/PlainYearMonth/PlainYearMonth.prototype.daysInYear.js b/Userland/Libraries/LibJS/Tests/builtins/Temporal/PlainYearMonth/PlainYearMonth.prototype.daysInYear.js
new file mode 100644
index 0000000000..d810a1da10
--- /dev/null
+++ b/Userland/Libraries/LibJS/Tests/builtins/Temporal/PlainYearMonth/PlainYearMonth.prototype.daysInYear.js
@@ -0,0 +1,14 @@
+describe("correct behavior", () => {
+    test("basic functionality", () => {
+        const plainYearMonth = new Temporal.PlainYearMonth(2021, 7);
+        expect(plainYearMonth.daysInYear).toBe(365);
+    });
+});
+
+describe("errors", () => {
+    test("this value must be a Temporal.PlainYearMonth object", () => {
+        expect(() => {
+            Reflect.get(Temporal.PlainYearMonth.prototype, "daysInYear", "foo");
+        }).toThrowWithMessage(TypeError, "Not a Temporal.PlainYearMonth");
+    });
+});