[RT 124214] add tests for returned NULL pointers

t/04-nativecall/04-pointers.c

@@ -18,3 +18,8 @@ DLLEXPORT int CompareSomePointer(void *ptr)
     int x = strcmp("Got passed back the pointer I returned", ptr) == 0;
     return x;
 }
+
+DLLEXPORT void * ReturnNullPointer()
+{
+    return NULL;
+}

t/04-nativecall/04-pointers.t

@@ -4,12 +4,13 @@ use lib 'lib';
 use NativeCall;
 use Test;
 
-plan 10;
+plan 13;
 
 compile_test_lib('04-pointers');
 
 sub ReturnSomePointer()         returns Pointer is native("./04-pointers") { * }
 sub CompareSomePointer(Pointer) returns int32   is native("./04-pointers") { * }
+sub ReturnNullPointer()         returns Pointer is native("./04-pointers") { * }
 
 my $x     = ReturnSomePointer();
 my int $a = 4321;
@@ -24,3 +25,6 @@ is Pointer.new(0).gist,    'Pointer<NULL>',   'Pointer.new(0) gistifies to "Poin
 is Pointer.new(1234).gist, 'Pointer<0x4d2>',  'Pointer.new(1234) gistifies to "Pointer<0x4d2>"';
 is Pointer.new($a).gist,   'Pointer<0x10e1>', 'Pointer.new accepts a native int too';
 is Pointer.gist,           '(Pointer)',       'The Pointer type object gistifies ot "Pointer"';
+is ReturnNullPointer().gist, '(Pointer)',     'A returned NULL pointer is the Pointer type object itself';
+ok ReturnNullPointer().defined == False,      'A returned NULL pointer is the Pointer type object itself';
+ok ReturnNullPointer().Bool == False,         'A returned NULL pointer is the Pointer type object itself';