LibWeb: Only use code unit length for is_code_unit_prefix

Fixes a crash in the included test.
Author: https://github.com/shannonbooth Commit: 74334ea1ce Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/4702 Reviewed-by: https://github.com/gmta ✅
2025-07-29 12:19:54 +00:00 · 2025-05-12 20:12:30 +12:00 · 2025-05-12 20:12:30 +12:00 · 74334ea1ce · 2025-05-12 09:21:40 +00:00
commit 74334ea1ce
parent 1cd09724f1
3 changed files with 55 additions and 7 deletions
--- a/Tests/LibWeb/TestStrings.cpp
+++ b/Tests/LibWeb/TestStrings.cpp
@ -0,0 +1,45 @@
+/*
+ * Copyright (c) 2025, Shannon Booth <shannon@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <LibTest/TestCase.h>
+#include <LibWeb/Infra/Strings.h>
+
+TEST_CASE(is_code_unit_prefix)
+{
+
+    // Basic prefix match
+    EXPECT(Web::Infra::is_code_unit_prefix("abc"sv, "abcde"sv));
+
+    // Exact match
+    EXPECT(Web::Infra::is_code_unit_prefix("abc"sv, "abc"sv));
+
+    // Empty prefix
+    EXPECT(Web::Infra::is_code_unit_prefix(""sv, "abc"sv));
+
+    // Empty input string
+    EXPECT(!Web::Infra::is_code_unit_prefix("abc"sv, ""sv));
+
+    // Both strings empty
+    EXPECT(Web::Infra::is_code_unit_prefix(""sv, ""sv));
+
+    // Prefix longer than input string
+    EXPECT(!Web::Infra::is_code_unit_prefix("abcdef"sv, "abc"sv));
+
+    // Non-ASCII characters
+    EXPECT(Web::Infra::is_code_unit_prefix("こんにちは"sv, "こんにちは世界"sv));
+    EXPECT(!Web::Infra::is_code_unit_prefix("世界"sv, "こんにちは世界"sv));
+
+    EXPECT(Web::Infra::is_code_unit_prefix("こ"sv, "こん"sv));
+    EXPECT(!Web::Infra::is_code_unit_prefix("こん"sv, "こ"sv));
+
+    // Special characters
+    EXPECT(Web::Infra::is_code_unit_prefix("!@#"sv, "!@#$%^"sv));
+    EXPECT(!Web::Infra::is_code_unit_prefix("!@#$"sv, "!@#"sv));
+
+    // Case sensitivity
+    EXPECT(!Web::Infra::is_code_unit_prefix("abc"sv, "ABC"sv));
+    EXPECT(!Web::Infra::is_code_unit_prefix("ABC"sv, "abc"sv));
+}