diff --git a/src/proc/control/command-impl.hpp b/src/proc/control/command-impl.hpp
index 672a8400b..a316c0bf2 100644
--- a/src/proc/control/command-impl.hpp
+++ b/src/proc/control/command-impl.hpp
@@ -47,6 +47,7 @@
 #include "proc/control/command-mutation.hpp"
 #include "lib/typed-allocation-manager.hpp"
 #include "lib/bool-checkable.hpp"
+#include "lib/format-string.hpp"
 
 #include <boost/noncopyable.hpp>
 #include <boost/operators.hpp>
@@ -58,6 +59,7 @@
 namespace proc {
 namespace control {
   
+  using util::_Fmt;
   using std::function;
   using std::shared_ptr;
   
@@ -219,6 +221,15 @@ namespace control {
           return isValid() && pClo_->isCaptured();
         }
       
+      operator string()  const
+        {
+          return _Fmt("Cmd|valid:%s, exec:%s, undo:%s |%s")
+                     % isValid()
+                     % canExec()
+                     % canUndo()
+                     % (pClo_? string(*pClo_) : util::FAILURE_INDICATOR);
+        }
+      
       
       
       friend bool
diff --git a/tests/gui/test/test-nexus.cpp b/tests/gui/test/test-nexus.cpp
index d9b9bbbff..45a266c38 100644
--- a/tests/gui/test/test-nexus.cpp
+++ b/tests/gui/test/test-nexus.cpp
@@ -449,7 +449,7 @@ namespace test{
         void
         performExec (CommandImpl& command)  const override
           {
-            log_.call ("TestNexus", "exec");
+            log_.call ("MockHandlingPattern", "exec", command);
             command.invokeCapture();
             command.invokeOperation();
           }
@@ -457,7 +457,7 @@ namespace test{
         void
         performUndo (CommandImpl& command)  const override
           {
-            log_.call ("TestNexus", "undo");
+            log_.call ("MockHandlingPattern", "undo", command);
             command.invokeUndo();
           }