Temporal: Add tests for PlainMonthDay.from with month and invalid monthCode

Author: gibson042

test/built-ins/Temporal/PlainMonthDay/from/monthcode-invalid.js

@@ -9,15 +9,23 @@ features: [Temporal]
 
 ["m1", "M1", "m01"].forEach((monthCode) => {
   assert.throws(RangeError, () => Temporal.PlainMonthDay.from({ monthCode, day: 17 }),
-    `monthCode '${monthCode}' is not well-formed`);
+    `monthCode '${monthCode}' is not well-formed (without numeric month)`);
+  assert.throws(RangeError, () => Temporal.PlainMonthDay.from({ month: 1, monthCode, day: 17 }),
+    `monthCode '${monthCode}' is not well-formed (with numeric month)`);
 });
 
 assert.throws(RangeError, () => Temporal.PlainMonthDay.from({ year: 2021, month: 12, monthCode: "M11", day: 17 }),
   "monthCode and month conflict");
 
 ["M00", "M19", "M99", "M13", "M00L", "M05L", "M13L"].forEach((monthCode) => {
   assert.throws(RangeError, () => Temporal.PlainMonthDay.from({ monthCode, day: 17 }),
-    `monthCode '${monthCode}' is not valid for ISO 8601 calendar`);
+    `monthCode '${monthCode}' is not valid for ISO 8601 calendar (without numeric month)`);
+  var plausibleMonth = Number(monthCode.slice(1, 3)) + (monthCode.length - 3);
+  assert.throws(
+    RangeError,
+    () => Temporal.PlainMonthDay.from({ month: plausibleMonth, monthCode, day: 17 }),
+    `monthCode '${monthCode}' is not valid for ISO 8601 calendar (with numeric month)`
+  );
 });
 
 assert.throws(