Index: tests/natools-s_expressions-cache_tests.adb
==================================================================
--- tests/natools-s_expressions-cache_tests.adb
+++ tests/natools-s_expressions-cache_tests.adb
@@ -115,11 +115,11 @@
          Print_Info (Pool);
          Flush;
       end Info_Pool;
    begin
       declare
-         Cache : Debug_Caches.Reference;
+         Cache, Deep, Shallow : Debug_Caches.Reference;
       begin
          Inject_Test (Cache);
 
          declare
             First : Debug_Caches.Cursor := Cache.First;
@@ -128,10 +128,24 @@
          begin
             Output.Set_Expected (Canonical_Test);
             Printers.Transfer (First, Pr);
             Output.Check_Stream (Test);
          end;
+
+         Deep := Cache.Duplicate;
+         Shallow := Deep;
+         Deep.Append_Atom (To_Atom ("more"));
+
+         declare
+            Other : Debug_Caches.Cursor := Deep.First;
+            Output : aliased Test_Tools.Memory_Stream;
+            Pr : Printers.Canonical (Output'Access);
+         begin
+            Output.Set_Expected (Canonical_Test & To_Atom ("4:more"));
+            Printers.Transfer (Other, Pr);
+            Output.Check_Stream (Test);
+         end;
 
          declare
             Second : Debug_Caches.Cursor := Cache.First;
             Output : aliased Test_Tools.Memory_Stream;
             Pr : Printers.Canonical (Output'Access);
@@ -138,10 +152,20 @@
          begin
             Output.Set_Expected (Canonical_Test);
             Printers.Transfer (Second, Pr);
             Output.Check_Stream (Test);
          end;
+
+         declare
+            Second_Other : Debug_Caches.Cursor := Shallow.First;
+            Output : aliased Test_Tools.Memory_Stream;
+            Pr : Printers.Canonical (Output'Access);
+         begin
+            Output.Set_Expected (Canonical_Test & To_Atom ("4:more"));
+            Printers.Transfer (Second_Other, Pr);
+            Output.Check_Stream (Test);
+         end;
       end;
 
       Info_Pool;
    exception
       when Error : others => Test.Report_Exception (Error);
@@ -150,11 +174,11 @@
 
    procedure Default_Instantiation (Report : in out NT.Reporter'Class) is
       Test : NT.Test := Report.Item ("Default instantiation");
    begin
       declare
-         Cache : Caches.Reference;
+         Cache, Deep, Shallow : Caches.Reference;
       begin
          Inject_Test (Cache);
 
          declare
             First : Caches.Cursor := Cache.First;
@@ -163,10 +187,24 @@
          begin
             Output.Set_Expected (Canonical_Test);
             Printers.Transfer (First, Pr);
             Output.Check_Stream (Test);
          end;
+
+         Deep := Cache.Duplicate;
+         Shallow := Deep;
+         Deep.Append_Atom (To_Atom ("more"));
+
+         declare
+            Other : Caches.Cursor := Deep.First;
+            Output : aliased Test_Tools.Memory_Stream;
+            Pr : Printers.Canonical (Output'Access);
+         begin
+            Output.Set_Expected (Canonical_Test & To_Atom ("4:more"));
+            Printers.Transfer (Other, Pr);
+            Output.Check_Stream (Test);
+         end;
 
          declare
             Second : Caches.Cursor := Cache.First;
             Output : aliased Test_Tools.Memory_Stream;
             Pr : Printers.Canonical (Output'Access);
@@ -173,11 +211,21 @@
          begin
             Output.Set_Expected (Canonical_Test);
             Printers.Transfer (Second, Pr);
             Output.Check_Stream (Test);
          end;
+
+         declare
+            Second_Other : Caches.Cursor := Shallow.First;
+            Output : aliased Test_Tools.Memory_Stream;
+            Pr : Printers.Canonical (Output'Access);
+         begin
+            Output.Set_Expected (Canonical_Test & To_Atom ("4:more"));
+            Printers.Transfer (Second_Other, Pr);
+            Output.Check_Stream (Test);
+         end;
       end;
    exception
       when Error : others => Test.Report_Exception (Error);
    end Default_Instantiation;
 
 end Natools.S_Expressions.Cache_Tests;