Revert "Revert "Cleanup some numeric code.""

core/src/fxcrt/fx_extension_unittest.cpp

Index: core/src/fxcrt/fx_extension_unittest.cpp
diff --git a/core/src/fxcrt/fx_extension_unittest.cpp b/core/src/fxcrt/fx_extension_unittest.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..e2017fc3ed35564ad1326b933c93531908eb29d0
--- /dev/null
+++ b/core/src/fxcrt/fx_extension_unittest.cpp
@@ -0,0 +1,14 @@
+// Copyright 2015 PDFium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "testing/gtest/include/gtest/gtest.h"
+
+#include "../../include/fxcrt/fx_ext.h"
+
+TEST(fxcrt, HexCharToDigit) {
+  EXPECT_EQ(10, HexCharToDigit('a'));
+  EXPECT_EQ(10, HexCharToDigit('A'));
+  EXPECT_EQ(7, HexCharToDigit('7'));
+  EXPECT_EQ(0, HexCharToDigit('i'));
+}