AK+LibUnicode: Provide Unicode-aware String case transformations

Since AK can't refer to LibUnicode directly, the strategy here is that
if you need case transformations, you can link LibUnicode and receive
them. If you try to use either of these methods without linking it, then
you'll of course get a linker error (note we don't do any fallbacks to
e.g. ASCII case transformations). If you don't need these methods, you
don't have to link LibUnicode.

2 files changed, 40 insertions, 0 deletions

diff --git a/Tests/AK/CMakeLists.txt b/Tests/AK/CMakeLists.txt
index e7e0c0855f..957304cb77 100644
--- a/Tests/AK/CMakeLists.txt
+++ b/Tests/AK/CMakeLists.txt
@@ -86,3 +86,5 @@ set(AK_TEST_SOURCES
 foreach(source IN LISTS AK_TEST_SOURCES)
     serenity_test("${source}" AK)
 endforeach()
+
+target_link_libraries(TestString PRIVATE LibUnicode)
diff --git a/Tests/AK/TestString.cpp b/Tests/AK/TestString.cpp
index 3cc88317a9..3faaa3b654 100644
--- a/Tests/AK/TestString.cpp
+++ b/Tests/AK/TestString.cpp
@@ -107,3 +107,41 @@ TEST_CASE(replace)
         EXPECT_EQ(result, "anon@courage:~"sv);
     }
 }
+
+TEST_CASE(to_lowercase)
+{
+    {
+        auto string = MUST(String::from_utf8("Aa"sv));
+        auto result = MUST(string.to_lowercase());
+        EXPECT_EQ(result, "aa"sv);
+    }
+    {
+        auto string = MUST(String::from_utf8("Ωω"sv));
+        auto result = MUST(string.to_lowercase());
+        EXPECT_EQ(result, "ωω"sv);
+    }
+    {
+        auto string = MUST(String::from_utf8("İi̇"sv));
+        auto result = MUST(string.to_lowercase());
+        EXPECT_EQ(result, "i̇i̇"sv);
+    }
+}
+
+TEST_CASE(to_uppercase)
+{
+    {
+        auto string = MUST(String::from_utf8("Aa"sv));
+        auto result = MUST(string.to_uppercase());
+        EXPECT_EQ(result, "AA"sv);
+    }
+    {
+        auto string = MUST(String::from_utf8("Ωω"sv));
+        auto result = MUST(string.to_uppercase());
+        EXPECT_EQ(result, "ΩΩ"sv);
+    }
+    {
+        auto string = MUST(String::from_utf8("ʼn"sv));
+        auto result = MUST(string.to_uppercase());
+        EXPECT_EQ(result, "ʼN"sv);
+    }
+}