Index: tests/natools-s_expressions-test_tools.adb
==================================================================
--- tests/natools-s_expressions-test_tools.adb
+++ tests/natools-s_expressions-test_tools.adb
@@ -375,10 +375,54 @@
             Test.Fail ("Wrong exception raised in Read_Atom");
             Test.Report_Exception (Error, NT.Fail);
       end Read_Atom_Test;
    end Test_Atom_Accessor_Exceptions;
 
+
+   procedure Next_And_Check
+     (Test : in out NT.Test;
+      Tested : in out Descriptor'Class;
+      Expected : in Events.Event;
+      Level : in Natural)
+   is
+      Event : Events.Event;
+   begin
+      Tested.Next (Event);
+      if Event /= Expected then
+         Test.Fail ("Found event "
+           & Events.Event'Image (Event)
+           & ", expected "
+           & Events.Event'Image (Expected));
+      elsif Tested.Current_Level /= Level then
+         Test.Fail ("Found event "
+           & Events.Event'Image (Event)
+           & " at level"
+           & Integer'Image (Tested.Current_Level)
+           & ", expected"
+           & Integer'Image (Level));
+      end if;
+   end Next_And_Check;
+
+
+   procedure Next_And_Check
+     (Test : in out NT.Test;
+      Tested : in out Descriptor'Class;
+      Expected : in Atom;
+      Level : in Natural)
+   is
+      Event : Events.Event;
+   begin
+      Tested.Next (Event);
+      if Event /= Events.Add_Atom then
+         Test.Fail ("Found event "
+           & Events.Event'Image (Event)
+           & ", expected Add_Atom");
+      else
+         Test_Tools.Test_Atom_Accessors (Test, Tested, Expected, Level);
+      end if;
+   end Next_And_Check;
+
 
 
    -------------------
    -- Memory Stream --
    -------------------

Index: tests/natools-s_expressions-test_tools.ads
==================================================================
--- tests/natools-s_expressions-test_tools.ads
+++ tests/natools-s_expressions-test_tools.ads
@@ -66,10 +66,25 @@
    procedure Test_Atom_Accessor_Exceptions
      (Test : in out NT.Test;
       Tested : in Descriptor'Class);
       --  Check that all atom accessors raise Program_Error
 
+   procedure Next_And_Check
+     (Test : in out NT.Test;
+      Tested : in out Descriptor'Class;
+      Expected : in Events.Event;
+      Level : in Natural);
+      --  Call Tested.Next and check the current event and level
+
+   procedure Next_And_Check
+     (Test : in out NT.Test;
+      Tested : in out Descriptor'Class;
+      Expected : in Atom;
+      Level : in Natural);
+      --  Call Tested.Next and check current event is Add_Atom with Expected,
+      --  using Test_Atom_Accessors.
+
 
    type Memory_Stream is new Ada.Streams.Root_Stream_Type with private;
 
    overriding procedure Read
      (Stream : in out Memory_Stream;