diff --git a/test/intl402/DisplayNames/prototype/of/type-region-invalid.js b/test/intl402/DisplayNames/prototype/of/type-region-invalid.js
new file mode 100644
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+++ b/test/intl402/DisplayNames/prototype/of/type-region-invalid.js
@@ -0,0 +1,83 @@
+// Copyright 2023 Igalia S.L. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+/*---
+esid: sec-Intl.DisplayNames.prototype.of
+description: Throws a RangeError for invalid `region` codes
+info: |
+  12.5.1 CanonicalCodeForDisplayNames ( code )
+
+  ...
+  2. If type is "region", then
+    a. If code cannot be matched by the unicode_region_subtag Unicode locale nonterminal, throw a RangeError exception.
+    b. Return the ASCII-uppercase of code.
+features: [Intl.DisplayNames]
+---*/
+
+// https://unicode.org/reports/tr35/#unicode_region_subtag
+// unicode_region_subtag	= (alpha{2} | digit{3}) ;
+
+var displayNames = new Intl.DisplayNames(undefined, {type: 'region'});
+
+assert.throws(RangeError, function() {
+  displayNames.of('00');
+}, 'insufficient length, numeric');
+
+assert.throws(RangeError, function() {
+  displayNames.of('a');
+}, 'insufficient length, alpha');
+
+assert.throws(RangeError, function() {
+  displayNames.of('aaa');
+}, 'excessive length, alpha');
+
+assert.throws(RangeError, function() {
+  displayNames.of('1111');
+}, 'excessive length, numeric');
+
+assert.throws(RangeError, function() {
+  displayNames.of('');
+}, 'empty string');
+
+assert.throws(RangeError, function() {
+  displayNames.of('a01');
+}, 'mixed alphanumeric (alpha first, length 3)');
+
+assert.throws(RangeError, function() {
+  displayNames.of('a1');
+}, 'mixed alphanumeric (alpha first, length 2)');
+
+assert.throws(RangeError, function() {
+  displayNames.of('1a');
+}, 'mixed alphanumeric (numeric first, length 2)');
+
+assert.throws(RangeError, function() {
+  displayNames.of('1a1');
+}, 'mixed alphanumeric (numeric first, length 3)');
+
+assert.throws(RangeError, function() {
+  displayNames.of('-111');
+}, 'leading separator (dash)');
+
+assert.throws(RangeError, function() {
+  displayNames.of('_111');
+}, 'leading separator (underscore)');
+
+assert.throws(RangeError, function() {
+  displayNames.of('111-');
+}, 'trailing separator (dash)');
+
+assert.throws(RangeError, function() {
+  displayNames.of('111-');
+}, 'trailing separator (underscore)');
+
+assert.throws(RangeError, function() {
+  displayNames.of(' aa');
+}, 'leading space');
+
+assert.throws(RangeError, function() {
+  displayNames.of('aa ');
+}, 'trailing space');
+
+assert.throws(RangeError, function() {
+  displayNames.of('a c');
+}, 'interstitial space');