Index: tests/natools-string_slice_tests.adb
==================================================================
--- tests/natools-string_slice_tests.adb
+++ tests/natools-string_slice_tests.adb
@@ -1,7 +1,7 @@
 ------------------------------------------------------------------------------
--- Copyright (c) 2013, Natacha Porté                                        --
+-- Copyright (c) 2013-2017, Natacha Porté                                   --
 --                                                                          --
 -- Permission to use, copy, modify, and distribute this software for any    --
 -- purpose with or without fee is hereby granted, provided that the above   --
 -- copyright notice and this permission notice appear in all copies.        --
 --                                                                          --
@@ -78,10 +78,11 @@
       Test_Incoming_Range (Report);
       Test_Invalid_Extensions (Report);
       Test_Null_Slice (Report);
       Test_Outgoing_Range (Report);
       Test_Subslices (Report);
+      Test_New_Slice (Report);
    end Slice_Tests;
 
 
 
    ----------------------
@@ -456,10 +457,80 @@
       end if;
    exception
       when Error : others => Report.Report_Exception (Name, Error);
    end Test_Is_Subrange;
 
+
+   procedure Test_New_Slice (Report : in out NT.Reporter'Class) is
+      Name : constant String := "Callback-based constructor";
+      First : constant Positive := 42;
+      Last : constant Natural := First + Name'Length - 1;
+      Result : Boolean := True;
+
+      procedure Initialize (S : out String);
+
+      procedure Initialize (S : out String) is
+      begin
+         S := Name;
+      end Initialize;
+   begin
+      declare
+         Slice : constant String_Slices.Slice
+           := String_Slices.New_Slice (First, Last, Initialize'Access);
+      begin
+         if Slice.First /= First then
+            if Result then
+               Report.Item (Name, NT.Fail);
+            end if;
+
+            Report.Info ("Incorrect value"
+              & Integer'Image (Slice.First) & " for Slice.First, expected"
+              & Integer'Image (First));
+            Result := False;
+         end if;
+
+         if Slice.Last /= Last then
+            if Result then
+               Report.Item (Name, NT.Fail);
+            end if;
+
+            Report.Info ("Incorrect value"
+              & Integer'Image (Slice.Last) & " for Slice.Last, expected"
+              & Integer'Image (Last));
+            Result := False;
+         end if;
+
+         if Slice.Length /= Name'Length then
+            if Result then
+               Report.Item (Name, NT.Fail);
+            end if;
+
+            Report.Info ("Incorrect value"
+              & Integer'Image (Slice.Length) & " for Slice.Length, expected"
+              & Integer'Image (Name'Length));
+            Result := False;
+         end if;
+
+         if Slice.To_String /= Name then
+            if Result then
+               Report.Item (Name, NT.Fail);
+            end if;
+
+            Report.Info ("Incorrect string """
+              & Integer'Image (Slice.Length) & """ in Slice, expected """
+              & Name & '"');
+            Result := False;
+         end if;
+      end;
+
+      if Result then
+         Report.Item (Name, NT.Success);
+      end if;
+   exception
+      when Error : others => Report.Report_Exception (Name, Error);
+   end Test_New_Slice;
+
 
    procedure Test_Null_Slice (Report : in out NT.Reporter'Class) is
       procedure Check_Null (S : in String);
 
       Name : constant String := "Null slice to empty string";

Index: tests/natools-string_slice_tests.ads
==================================================================
--- tests/natools-string_slice_tests.ads
+++ tests/natools-string_slice_tests.ads
@@ -1,7 +1,7 @@
 ------------------------------------------------------------------------------
--- Copyright (c) 2013, Natacha Porté                                        --
+-- Copyright (c) 2013-2017, Natacha Porté                                   --
 --                                                                          --
 -- Permission to use, copy, modify, and distribute this software for any    --
 -- purpose with or without fee is hereby granted, provided that the above   --
 -- copyright notice and this permission notice appear in all copies.        --
 --                                                                          --
@@ -38,11 +38,12 @@
    procedure Test_Conversions (Report : in out NT.Reporter'Class);
    procedure Test_Extensions (Report : in out NT.Reporter'Class);
    procedure Test_Incoming_Range (Report : in out NT.Reporter'Class);
    procedure Test_Invalid_Extensions (Report : in out NT.Reporter'Class);
    procedure Test_Invalid_Subslices (Report : in out NT.Reporter'Class);
+   procedure Test_New_Slice (Report : in out NT.Reporter'Class);
    procedure Test_Null_Slice (Report : in out NT.Reporter'Class);
    procedure Test_Outgoing_Range (Report : in out NT.Reporter'Class);
    procedure Test_Slice_Relations (Report : in out NT.Reporter'Class);
    procedure Test_Subslices (Report : in out NT.Reporter'Class);
 
 end Natools.String_Slice_Tests;