Temporal: Extend PlainDate#with coverage.

test/built-ins/Temporal/PlainDate/prototype/with/calendar-invalid-return.js

@@ -0,0 +1,36 @@
+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaindate.prototype.with
+description: Throw when the returned value is not a PlainDate.
+features: [Temporal]
+---*/
+
+class CustomCalendar extends Temporal.Calendar {
+  constructor(value) {
+    super("iso8601");
+    this.value = value;
+  }
+  dateFromFields() {
+    return this.value;
+  }
+}
+
+const tests = [
+  [undefined],
+  [null, "null"],
+  [true],
+  ["2000-05"],
+  [Symbol()],
+  [200005],
+  [200005n],
+  [{}, "plain object"],
+  [() => {}, "lambda"],
+  [Temporal.PlainDate, "Temporal.PlainDate"],
+  [Temporal.PlainDate.prototype, "Temporal.PlainDate.prototype"],
+];
+for (const [test, description = typeof test] of tests) {
+  const plainDate = new Temporal.PlainDate(2000, 5, 2, new CustomCalendar(test));
+  assert.throws(TypeError, () => plainDate.with({ year: 1 }), `Expected error with ${description}`);
+}

test/built-ins/Temporal/PlainDate/prototype/with/custom.js

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+// Copyright (C) 2022 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.plaindate.prototype.with
+description: Basic tests with custom calendar
+includes: [compareArray.js,temporalHelpers.js]
+features: [Temporal]
+---*/
+
+const result = new Temporal.PlainDate(1920, 5, 3);
+const options = {};
+let calls = 0;
+class CustomCalendar extends Temporal.Calendar {
+  constructor() {
+    super("iso8601");
+  }
+  dateFromFields(...args) {
+    ++calls;
+    assert.sameValue(args.length, 2, "Two arguments");
+    assert.sameValue(typeof args[0], "object", "First argument: type");
+    assert.sameValue(args[0].day, 18, "First argument: day");
+    assert.sameValue(args[0].month, 11, "First argument: month");
+    assert.sameValue(args[0].monthCode, "M11", "First argument: monthCode");
+    assert.sameValue(args[0].year, 43, "First argument: year");
+    assert.sameValue(args[1], options, "Second argument");
+    return result;
+  }
+}
+const calendar = new CustomCalendar();
+const plainDate = new Temporal.PlainDate(1976, 11, 18, calendar);
+assert.sameValue(plainDate.with({ year: 43 }, options), result);
+assert.sameValue(calls, 1);