Cleanup use of messaget in unit tests

Constructing a messaget without a message handler is deprecated. Don't
unnecessarily include iostream, use a (null) message handler instead.

Author: tautschnig

jbmc/unit/solvers/strings/string_refinement/string_symbol_resolution.cpp

@@ -7,6 +7,7 @@ Author: Diffblue Ltd.
 
 \*******************************************************************/
 
+#include <testing-utils/message.h>
 #include <testing-utils/use_catch.h>
 
 #include <solvers/strings/string_refinement.h>
@@ -27,7 +28,7 @@ SCENARIO(
   register_language(new_java_bytecode_language);
   symbol_tablet symbol_table;
   namespacet ns(symbol_table);
-  messaget::mstreamt &stream = messaget().debug();
+  messaget::mstreamt &stream = messaget(null_message_handler).debug();
 
   GIVEN("Some equations")
   {

unit/analyses/dependence_graph.cpp

@@ -6,19 +6,20 @@ Author: Chris Smowton, [email protected]
 
 \*******************************************************************/
 
-#include <iostream>
-
-#include <analyses/dependence_graph.h>
-#include <ansi-c/ansi_c_language.h>
-#include <goto-programs/goto_convert_functions.h>
-#include <langapi/mode.h>
 #include <testing-utils/call_graph_test_utils.h>
+#include <testing-utils/message.h>
 #include <testing-utils/use_catch.h>
+
 #include <util/arith_tools.h>
 #include <util/c_types.h>
 #include <util/std_code.h>
 #include <util/symbol_table.h>
 
+#include <analyses/dependence_graph.h>
+#include <ansi-c/ansi_c_language.h>
+#include <goto-programs/goto_convert_functions.h>
+#include <langapi/mode.h>
+
 const std::set<goto_programt::const_targett>&
     dependence_graph_test_get_control_deps(const dep_graph_domaint &domain)
 {
@@ -83,8 +84,7 @@ SCENARIO("dependence_graph", "[core][analyses][dependence_graph]")
     goto_model.symbol_table.add(
       create_void_function_symbol("b", code_skipt()));
 
-    stream_message_handlert msg(std::cerr);
-    goto_convert(goto_model, msg);
+    goto_convert(goto_model, null_message_handler);
 
     WHEN("Constructing a dependence graph")
     {

unit/util/message.cpp

@@ -38,7 +38,7 @@ TEST_CASE("Assign a messaget")
   messaget msg1(handler1);
 
   // Assign messaget:
-  messaget msg2;
+  messaget msg2(handler1);
   msg2=msg1;
 
   // Change its handler: