Index: rostests/apitests/kernel32/CMakeLists.txt
===================================================================
--- rostests/apitests/kernel32/CMakeLists.txt	(revision 74717)
+++ rostests/apitests/kernel32/CMakeLists.txt	(working copy)
@@ -14,6 +14,7 @@
     GetDriveType.c
     GetModuleFileName.c
     interlck.c
+    IsDBCSLeadByteEx.c
     LoadLibraryExW.c
     lstrcpynW.c
     lstrlen.c
Index: rostests/apitests/kernel32/IsDBCSLeadByteEx.c
===================================================================
--- rostests/apitests/kernel32/IsDBCSLeadByteEx.c	(nonexistent)
+++ rostests/apitests/kernel32/IsDBCSLeadByteEx.c	(working copy)
@@ -0,0 +1,125 @@
+/*
+ * PROJECT:         ReactOS api tests
+ * LICENSE:         GPLv2+ - See COPYING in the top level directory
+ * PURPOSE:         Tests for IsDBCSLeadByteEx
+ * PROGRAMMER:      Katayama Hirofumi MZ <katayama.hirofumi.mz@gmail.com>
+ */
+
+#include <apitest.h>
+
+#define WIN32_NO_STATUS
+#define _INC_WINDOWS
+#define COM_NO_WINDOWS_H
+#include <stdio.h>
+#include <winnls.h>
+
+#define MAX_RANGE   4
+
+typedef struct RANGE
+{
+    int StartIndex;
+    int EndIndex;
+} RANGE;
+
+typedef struct ENTRY
+{
+    const char *Name;
+    int CodePage;
+    int RangeCount;
+    RANGE Ranges[MAX_RANGE];
+} ENTRY;
+
+START_TEST(IsDBCSLeadByteEx)
+{
+    static const ENTRY Entries[] =
+    {
+        {
+            "English", 437,
+            0
+        },
+        {
+            "ChineseSimpilified", 936,
+            1,
+            {
+                { 0x81, 0xFE }
+            }
+        },
+        {
+            "ChineseTraditional", 950,
+            1,
+            {
+                { 0x81, 0xFE }
+            }
+        },
+        {
+            "Japanese", 932,
+            2,
+            {
+                { 0x81, 0x9F }, { 0xE0, 0xFC }
+            }
+        },
+        {
+            "Korean", 949,
+            1,
+            {
+                { 0x81, 0xFE }
+            }
+        }
+    };
+    int i;
+
+    for (i = 0; i < _countof(Entries); ++i)
+    {
+        int Index, iRange;
+        int CodePage = Entries[i].CodePage, StartIndex = 0, RangeCount = 0;
+        BOOL InRange = FALSE;
+        RANGE Ranges[MAX_RANGE];
+        const char *Name = Entries[i].Name;
+
+        ZeroMemory(&Ranges, sizeof(Ranges));
+
+        for (Index = 0; Index < 256; ++Index)
+        {
+            if (InRange)
+            {
+                if (!IsDBCSLeadByteEx(CodePage, Index))
+                {
+                    Ranges[RangeCount].StartIndex = StartIndex;
+                    Ranges[RangeCount].EndIndex = Index - 1;
+                    ++RangeCount;
+                    InRange = FALSE;
+                }
+            }
+            else
+            {
+                if (IsDBCSLeadByteEx(CodePage, Index))
+                {
+                    StartIndex = Index;
+                    InRange = TRUE;
+                }
+            }
+        }
+        if (InRange)
+        {
+            Ranges[RangeCount].StartIndex = StartIndex;
+            Ranges[RangeCount].EndIndex = Index - 1;
+            ++RangeCount;
+        }
+
+        ok(RangeCount == Entries[i].RangeCount,
+           "%s: RangeCount expected %d, was %d\n",
+           Name, Entries[i].RangeCount, RangeCount);
+        for (iRange = 0; iRange < Entries[i].RangeCount; ++iRange)
+        {
+            const RANGE *pRange = &Entries[i].Ranges[iRange];
+            int iStart = Ranges[iRange].StartIndex;
+            int iEnd = Ranges[iRange].EndIndex;
+            ok(iStart == pRange->StartIndex,
+               "%s: Ranges[%d].StartIndex expected: 0x%02X, was: 0x%02X\n",
+               Name, iRange, pRange->StartIndex, iStart);
+            ok(iEnd == pRange->EndIndex,
+               "%s: Ranges[%d].EndIndex was expected: 0x%02X, was: 0x%02X\n",
+               Name, iRange, pRange->EndIndex, iEnd);
+        }
+    }
+}
Index: rostests/apitests/kernel32/testlist.c
===================================================================
--- rostests/apitests/kernel32/testlist.c	(revision 74717)
+++ rostests/apitests/kernel32/testlist.c	(working copy)
@@ -15,6 +15,7 @@
 extern void func_GetDriveType(void);
 extern void func_GetModuleFileName(void);
 extern void func_interlck(void);
+extern void func_IsDBCSLeadByteEx(void);
 extern void func_LoadLibraryExW(void);
 extern void func_lstrcpynW(void);
 extern void func_lstrlen(void);
@@ -42,6 +43,7 @@
     { "GetDriveType",                func_GetDriveType },
     { "GetModuleFileName",           func_GetModuleFileName },
     { "interlck",                    func_interlck },
+    { "IsDBCSLeadByteEx",            func_IsDBCSLeadByteEx },
     { "LoadLibraryExW",              func_LoadLibraryExW },
     { "lstrcpynW",                   func_lstrcpynW },
     { "lstrlen",                     func_lstrlen },