3 files changed, 60 insertions, 0 deletions
diff --git a/libc/test/src/ctype/CMakeLists.txt b/libc/test/src/ctype/CMakeLists.txt
index 0d77134b95eb..4141708fc2b4 100644
--- a/libc/test/src/ctype/CMakeLists.txt
+++ b/libc/test/src/ctype/CMakeLists.txt
@@ -119,3 +119,23 @@ add_libc_unittest(
   DEPENDS
     libc.src.ctype.isxdigit
 )
+
+add_libc_unittest(
+  tolower
+  SUITE
+    libc_ctype_unittests
+  SRCS
+    tolower_test.cpp
+  DEPENDS
+    libc.src.ctype.tolower
+)
+
+add_libc_unittest(
+  toupper
+  SUITE
+    libc_ctype_unittests
+  SRCS
+    toupper_test.cpp
+  DEPENDS
+    libc.src.ctype.toupper
+)
diff --git a/libc/test/src/ctype/tolower_test.cpp b/libc/test/src/ctype/tolower_test.cpp
new file mode 100644
index 000000000000..096ef969bf63
--- /dev/null
+++ b/libc/test/src/ctype/tolower_test.cpp
@@ -0,0 +1,20 @@
+//===-- Unittests for tolower----------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/ctype/tolower.h"
+#include "utils/UnitTest/Test.h"
+
+TEST(ToLower, DefaultLocale) {
+  for (int ch = 0; ch < 255; ++ch) {
+    // This follows pattern 'A' + 32 = 'a'.
+    if ('A' <= ch && ch <= 'Z')
+      EXPECT_EQ(__llvm_libc::tolower(ch), ch + 32);
+    else
+      EXPECT_EQ(__llvm_libc::tolower(ch), ch);
+  }
+}
diff --git a/libc/test/src/ctype/toupper_test.cpp b/libc/test/src/ctype/toupper_test.cpp
new file mode 100644
index 000000000000..4d6a1b3d4f65
--- /dev/null
+++ b/libc/test/src/ctype/toupper_test.cpp
@@ -0,0 +1,20 @@
+//===-- Unittests for toupper----------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/ctype/toupper.h"
+#include "utils/UnitTest/Test.h"
+
+TEST(ToUpper, DefaultLocale) {
+  for (int ch = 0; ch < 255; ++ch) {
+    // This follows pattern 'a' - 32 = 'A'.
+    if ('a' <= ch && ch <= 'z')
+      EXPECT_EQ(__llvm_libc::toupper(ch), ch - 32);
+    else
+      EXPECT_EQ(__llvm_libc::toupper(ch), ch);
+  }
+}