Add unit test for StringUtil's newly added JoinStrings

Source/UnitTests/Common/StringUtilTest.cpp

@@ -0,0 +1,18 @@
+// Copyright 2016 Dolphin Emulator Project
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+#include <gtest/gtest.h>
+#include <string>
+#include <vector>
+
+#include "Common/StringUtil.h"
+
+TEST(StringUtil, JoinStrings)
+{
+  EXPECT_EQ("", JoinStrings({}, ", "));
+  EXPECT_EQ("a", JoinStrings({"a"}, ","));
+  EXPECT_EQ("ab", JoinStrings({"a", "b"}, ""));
+  EXPECT_EQ("a, bb, c", JoinStrings({"a", "bb", "c"}, ", "));
+  EXPECT_EQ("???", JoinStrings({"?", "?"}, "?"));
+}