decodeURIComponent test

Author: ayuan0828

test/built-ins/decodeURI/throws-URIError.js

@@ -0,0 +1,40 @@
+// Copyright (C) 2025 ayuan.  All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+description: Verify decodeURIComponent throws URIError for various invalid UTF-8 sequences
+esid: sec-decodeuricomponent-encodeduricomponent
+info: |
+    Invalid sequences include:
+    - Surrogate pair encoding
+    - Overlong encoding
+    - Invalid continuation bytes
+    - Incomplete sequences
+    - Out-of-range code points
+    Reference: https://stackoverflow.com/a/1319229/172999
+---*/
+
+// CHECK#1: Reserved surrogate pair (U+D800-DFFF)
+assert.throws(URIError, function CHECK1() {
+    decodeURIComponent('%ED%BF%BF');
+}, '#1: %ED%BF%BF (surrogate pair) should throw URIError');
+  
+// CHECK#2: Overlong encoding for ASCII character
+assert.throws(URIError, function CHECK2() {
+    decodeURIComponent('%C0%AF');
+}, '#2: %C0%AF (overlong encoding) should throw URIError');
+  
+// CHECK#3: Invalid continuation byte pattern
+assert.throws(URIError, function CHECK3() {
+    decodeURIComponent('%ED%7F%BF');
+}, '#3: %ED%7F%BF (invalid continuation) should throw URIError');
+  
+// CHECK#4: Incomplete 3-byte sequence
+assert.throws(URIError, function CHECK4() {
+    decodeURIComponent('%ED%BF');
+}, '#4: %ED%BF (incomplete sequence) should throw URIError');
+  
+// CHECK#5: Code point beyond U+10FFFF
+assert.throws(URIError, function CHECK5() {
+    decodeURIComponent('%F4%90%80%80');
+},'#5: %F4%90%80%80 (out-of-range) should throw URIError');