1 files changed, 70 insertions, 0 deletions

diff --git a/libcxx/test/input.output/string.streams/stringbuf/stringbuf.virtuals/underflow.pass.cpp b/libcxx/test/input.output/string.streams/stringbuf/stringbuf.virtuals/underflow.pass.cpp
new file mode 100644
index 00000000000..1f5b91e79c4
--- /dev/null
+++ b/libcxx/test/input.output/string.streams/stringbuf/stringbuf.virtuals/underflow.pass.cpp
@@ -0,0 +1,70 @@
+//===----------------------------------------------------------------------===//
+//
+// ΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚΚThe LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <sstream>
+
+// template <class charT, class traits = char_traits<charT>, class Allocator = allocator<charT> >
+// class basic_stringbuf
+
+// int_type underflow();
+
+#include <sstream>
+#include <cassert>
+
+template <class CharT>
+struct testbuf
+    : public std::basic_stringbuf<CharT>
+{
+    typedef std::basic_stringbuf<CharT> base;
+    explicit testbuf(const std::basic_string<CharT>& str)
+        : base(str) {}
+
+    typename base::int_type underflow() {return base::underflow();}
+    void pbump(int n) {base::pbump(n);}
+};
+
+int main()
+{
+    {
+        testbuf<char> sb("123");
+        sb.pbump(3);
+        assert(sb.underflow() == '1');
+        assert(sb.underflow() == '1');
+        assert(sb.snextc() == '2');
+        assert(sb.underflow() == '2');
+        assert(sb.underflow() == '2');
+        assert(sb.snextc() == '3');
+        assert(sb.underflow() == '3');
+        assert(sb.underflow() == '3');
+        assert(sb.snextc() == std::char_traits<char>::eof());
+        assert(sb.underflow() == std::char_traits<char>::eof());
+        assert(sb.underflow() == std::char_traits<char>::eof());
+        sb.sputc('4');
+        assert(sb.underflow() == '4');
+        assert(sb.underflow() == '4');
+    }
+    {
+        testbuf<wchar_t> sb(L"123");
+        sb.pbump(3);
+        assert(sb.underflow() == L'1');
+        assert(sb.underflow() == L'1');
+        assert(sb.snextc() == L'2');
+        assert(sb.underflow() == L'2');
+        assert(sb.underflow() == L'2');
+        assert(sb.snextc() == L'3');
+        assert(sb.underflow() == L'3');
+        assert(sb.underflow() == L'3');
+        assert(sb.snextc() == std::char_traits<wchar_t>::eof());
+        assert(sb.underflow() == std::char_traits<wchar_t>::eof());
+        assert(sb.underflow() == std::char_traits<wchar_t>::eof());
+        sb.sputc(L'4');
+        assert(sb.underflow() == L'4');
+        assert(sb.underflow() == L'4');
+    }
+}