Add test of null shared pointers emitted from C++

This tests nulls emitted as pointers and values of shared pointers,
created from null, from references, and from default constructors.

Author: sethrj

Examples/test-suite/li_boost_shared_ptr.i

@@ -242,6 +242,10 @@ std::string nullsmartpointerpointertest(SwigBoost::shared_ptr<Klass>* k) {
   else
     return "also not null";
 }
+
+SwigBoost::shared_ptr<Klass>* sp_pointer_null() { return NULL; }
+SwigBoost::shared_ptr<Klass>* null_sp_pointer() { static SwigBoost::shared_ptr<Klass> static_sp; return &static_sp; }
+SwigBoost::shared_ptr<Klass> sp_value_null() { return SwigBoost::shared_ptr<Klass>(); }
 // $owner
 Klass *pointerownertest() {
   return new Klass("pointerownertest");

Examples/test-suite/python/li_boost_shared_ptr_runme.py

@@ -168,6 +168,19 @@ def runtest(self):
         except ValueError:
             pass
 
+        # test null pointers emitted from C++
+        k = li_boost_shared_ptr.sp_pointer_null()
+        if (li_boost_shared_ptr.smartpointertest(k) != None):
+            raise RuntimeError("return was not null")
+
+        k = li_boost_shared_ptr.null_sp_pointer()
+        if (li_boost_shared_ptr.smartpointertest(k) != None):
+            raise RuntimeError("return was not null")
+
+        k = li_boost_shared_ptr.sp_value_null()
+        if (li_boost_shared_ptr.smartpointertest(k) != None):
+            raise RuntimeError("return was not null")
+
         # $owner
         k = li_boost_shared_ptr.pointerownertest()
         val = k.getValue()