Merge and extract for PlainDateTime/prototype withCalendar

Author: Brage Hogstad

test/built-ins/Temporal/PlainDateTime/prototype/withCalendar/calendar-invalid-iso-string.js

@@ -0,0 +1,23 @@
+// Copyright (C) 2025 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaindatetime.prototype.withcalendar
+description: Invalid ISO 8601 string is not accepted as calendar
+features: [Temporal]
+---*/
+
+const instance = new Temporal.PlainDateTime(1976, 11, 18, 15, 23, 30, 123, 456, 789, "iso8601");
+
+const invalidStrings = [
+  ["", "empty string"],
+  ["1997-12-04[u-ca=iso8601]", "ISO string with calendar annotation"],
+];
+
+for (const [arg, description] of invalidStrings) {
+  assert.throws(
+    RangeError,
+    () => instance.withCalendar(arg),
+    `${description} is not a valid calendar ID`
+  );
+}

test/built-ins/Temporal/PlainDateTime/prototype/withCalendar/calendar-number.js

@@ -14,14 +14,16 @@ const instance = new Temporal.PlainDateTime(1976, 11, 18, 15, 23, 30, 123, 456,
 const primitiveTests = [
   [null, "null"],
   [true, "boolean"],
-  ["", "empty string"],
   [1, "number that doesn't convert to a valid ISO string"],
   [1n, "bigint"],
+  [19970327, "large number"],
+  [-19970327, "negative number"],
+  [1234567890, "very large integer"],
 ];
 
 for (const [arg, description] of primitiveTests) {
   assert.throws(
-    typeof arg === 'string' ? RangeError : TypeError,
+    TypeError,
     () => instance.withCalendar(arg),
     `${description} does not convert to a valid ISO string`
   );