Add test case to demonstrate the name collision that occurs in the generated C# code when a namespace is named System.

Examples/test-suite/csharp/Makefile.in

@@ -17,6 +17,7 @@ CPP_TEST_CASES = \
 	csharp_exceptions \
 	csharp_features \
 	csharp_lib_arrays \
+	csharp_namespace_system_collision \
 	csharp_prepost \
 	csharp_typemaps \
 	enum_thorough_simple \

Examples/test-suite/csharp_namespace_system_collision.i

@@ -0,0 +1,39 @@
+%module namespace_system_collision
+
+%{
+#include <string>
+
+namespace TopLevel
+{
+  namespace System
+  {
+    class Foo {
+    public:
+      virtual ~Foo() {}
+      virtual std::string ping() { return "TopLevel::System::Foo::ping()"; }
+    };
+  }
+}
+
+%}
+
+%include <std_string.i>
+
+// nspace feature only supported by these languages
+#if defined(SWIGJAVA) || defined(SWIGCSHARP) || defined(SWIGD)
+%nspace;
+#else
+#warning nspace feature not yet supported in this target language
+#endif
+
+namespace TopLevel
+{
+  namespace System
+  {
+    class Foo {
+    public:
+      virtual ~Foo();
+      virtual std::string ping();
+    };
+  }
+}