[libsigcplusplus/libsigc++-2-10] test_mem_fun: Test auto-disconnection with trackable.

[Murray Cumming <murrayc src gnome org>]

commit de51a87156a14c65fbd436b0c3ea0508fe9332e1
Author: Murray Cumming <murrayc murrayc com>
Date:   Fri Apr 1 11:40:27 2016 +0200

    test_mem_fun: Test auto-disconnection with trackable.
    
    This is probably tested somewhere else already, but I like having it
    here too because it is an important reason for slot<> to exist,
    compared to a simple std::function.

 tests/test_mem_fun.cc |   30 ++++++++++++++++++++++++++++++
 1 files changed, 30 insertions(+), 0 deletions(-)
---
diff --git a/tests/test_mem_fun.cc b/tests/test_mem_fun.cc
index 1b32ae6..403abba 100644
--- a/tests/test_mem_fun.cc
+++ b/tests/test_mem_fun.cc
@@ -142,6 +142,34 @@ void test_bound()
 #endif
 }
 
+class TestAutoDisconnect : public sigc::trackable
+{
+public:
+  void foo()
+  {
+    result_stream << "TestAutoDisconnect::foo() called.";
+  }
+};
+
+void test_auto_disconnect()
+{
+  //Check that slot doesn't try to call a method on a destroyed instance,
+  //when the instance's class derives from trackable.
+  sigc::slot<void()> slot_of_member_method;
+  {
+    TestAutoDisconnect t;
+    slot_of_member_method = sigc::mem_fun(t, &TestAutoDisconnect::foo);
+
+    //The method should be called:
+    slot_of_member_method();
+    util->check_result(result_stream, "TestAutoDisconnect::foo() called.");
+  }
+
+  //The method should not be called:
+  slot_of_member_method();
+  util->check_result(result_stream, "");
+}
+
 int
 main(int argc, char* argv[])
 {
@@ -163,5 +191,7 @@ main(int argc, char* argv[])
 
   test_bound();
 
+  test_auto_disconnect();
+
   return util->get_result_and_delete_instance() ? EXIT_SUCCESS : EXIT_FAILURE;
 }