Added possibility to log to stderr

src/alog-facilities-file_descriptor.adb

@@ -33,7 +33,8 @@ package body Alog.Facilities.File_Descriptor is
    is
       use Ada.Text_IO;
    begin
-      if Facility.Log_File_Ptr /= Standard_Output
+      if (Facility.Log_File_Ptr /= Standard_Output
+          and Facility.Log_File_Ptr /= Standard_Error)
         and Is_Open (File => Facility.Log_File)
       then
          if Remove then
@@ -56,6 +57,14 @@ package body Alog.Facilities.File_Descriptor is
 
    -------------------------------------------------------------------------
 
+   procedure Set_Log_Stderr (Facility : in out Instance)
+   is
+   begin
+      Facility.Log_File_Ptr := Ada.Text_IO.Standard_Error;
+   end Set_Log_Stderr;
+
+   -------------------------------------------------------------------------
+
    procedure Set_Logfile
      (Facility : in out Instance;
       Path     :        String;

src/alog-facilities-file_descriptor.ads

@@ -35,6 +35,9 @@ package Alog.Facilities.File_Descriptor is
    procedure Teardown (Facility : in out Instance);
    --  Implementation of Teardown-procedure.
 
+   procedure Set_Log_Stderr (Facility : in out Instance);
+   --  Enable logging to stderr.
+
    procedure Set_Logfile
      (Facility : in out Instance;
       Path     :        String;

tests/facility_tests-fd.adb

@@ -84,6 +84,9 @@ package body Facility_Tests.FD is
       T.Add_Test_Routine
         (Routine => Set_Invalid_Logfile_Fd'Access,
          Name    => "set invalid logfile");
+      T.Add_Test_Routine
+        (Routine => Set_Stderr'Access,
+         Name    => "set standard error as logfile");
       T.Add_Test_Routine
         (Routine => Write_Message_Fd'Access,
          Name    => "log a fd message");
@@ -125,6 +128,20 @@ package body Facility_Tests.FD is
 
    -------------------------------------------------------------------------
 
+   procedure Set_Stderr is
+      use type Ada.Text_IO.File_Access;
+
+      F : File_Descriptor.Instance;
+   begin
+      Assert (Condition => F.Get_Logfile /= Ada.Text_IO.Standard_Error,
+              Message   => "logfile already set to stderr");
+      F.Set_Log_Stderr;
+      Assert (Condition => F.Get_Logfile = Ada.Text_IO.Standard_Error,
+              Message   => "logfile not set to stderr");
+   end Set_Stderr;
+
+   -------------------------------------------------------------------------
+
    procedure Set_Valid_Logfile_Fd is
       use Ada.Text_IO;
       F : File_Descriptor.Instance;

tests/facility_tests-fd.ads

@@ -35,6 +35,9 @@ package Facility_Tests.FD is
    procedure Set_Invalid_Logfile_Fd;
    --  Set illegal Fd test.
 
+   procedure Set_Stderr;
+   --  Set stderr Fd test.
+
    procedure Write_Message_Fd;
    --  Test message writing.