Intl.RelativeTimeFormat: Add tests for invalid units in format/formatToParts.

test/intl402/RelativeTimeFormat/prototype/format/unit-invalid.js

+// Copyright 2018 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-Intl.RelativeTimeFormat.prototype.format
+description: Checks the handling of invalid unit arguments to Intl.RelativeTimeFormat.prototype.format().
+info: |
+    SingularRelativeTimeUnit ( unit )
+
+    10. If unit is not one of "second", "minute", "hour", "day", "week", "month", "quarter", "year", throw a RangeError exception.
+
+features: [Intl.RelativeTimeFormat]
+---*/
+
+const rtf = new Intl.RelativeTimeFormat("en-US");
+
+assert.sameValue(typeof rtf.format, "function");
+
+const values = [
+  undefined,
+  null,
+  true,
+  1,
+  0.1,
+  NaN,
+  {},
+  "",
+  "SECOND",
+  "MINUTE",
+  "HOUR",
+  "DAY",
+  "WEEK",
+  "MONTH",
+  "QUARTER",
+  "YEAR",
+];
+
+for (const value of values) {
+  assert.throws(RangeError, () => rtf.format(0, value), String(value));
+}
+
+const symbol = Symbol();
+assert.throws(TypeError, () => rtf.format(0, symbol), "symbol");

test/intl402/RelativeTimeFormat/prototype/formatToParts/unit-invalid.js

+// Copyright 2018 Igalia, S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-Intl.RelativeTimeFormat.prototype.formatToParts
+description: Checks the handling of invalid unit arguments to Intl.RelativeTimeFormat.prototype.formatToParts().
+info: |
+    SingularRelativeTimeUnit ( unit )
+
+    10. If unit is not one of "second", "minute", "hour", "day", "week", "month", "quarter", "year", throw a RangeError exception.
+
+features: [Intl.RelativeTimeFormat]
+---*/
+
+const rtf = new Intl.RelativeTimeFormat("en-US");
+
+assert.sameValue(typeof rtf.formatToParts, "function");
+
+const values = [
+  undefined,
+  null,
+  true,
+  1,
+  0.1,
+  NaN,
+  {},
+  "",
+  "SECOND",
+  "MINUTE",
+  "HOUR",
+  "DAY",
+  "WEEK",
+  "MONTH",
+  "QUARTER",
+  "YEAR",
+];
+
+for (const value of values) {
+  assert.throws(RangeError, () => rtf.formatToParts(0, value), String(value));
+}
+
+const symbol = Symbol();
+assert.throws(TypeError, () => rtf.formatToParts(0, symbol), "symbol");