ADDED   coverage.sh
Index: coverage.sh
==================================================================
--- coverage.sh
+++ coverage.sh
@@ -0,0 +1,5 @@
+#!/bin/sh
+gnatmake -p -Ptests -XMODE=Coverage || exit $?
+coverage/bin/test_all
+lcov --gcov-tool gnatgcov --directory coverage/obj --output coverage/test-info.dat --capture || exit $?
+genhtml --output-dir coverage coverage/test-info.dat

Index: natools.gpr
==================================================================
--- natools.gpr
+++ natools.gpr
@@ -1,9 +1,32 @@
 project Natools is
+   type Build_Type is ("Release", "Coverage");
+   Mode : Build_Type := external ("MODE", "Release");
+
+   Prefix := "";
+   Extra_Switches := ();
+
+   case Mode is
+      when "Release" =>
+         Prefix := "";
+      when "Coverage" =>
+         Prefix := "coverage/";
+   end case;
+
    --  Source_Dirs is left to default "."
    for Source_Dirs use ("src");
-   for Object_Dir use "obj";
+   for Object_Dir use Prefix & "obj";
+   for Exec_Dir use Prefix & "bin";
+
+   case Mode is
+      when "Release" =>
+         Extra_Switches := ("-O3");
+      when "Coverage" =>
+         Extra_Switches :=
+           ("-g", "-O0", "-fprofile-arcs", "-ftest-coverage");
+   end case;
+
 
    package Compiler is
       for Default_Switches ("Ada") use
         ("-gnatafnovy",
             --  a: assersions enabled
@@ -31,13 +54,13 @@
          "-gnateE",
             --  generate extra information in exception messages
          "-gnatwae",
             --  a: turn on most warnings
             --  e: treat all warnings as errors
-         "-fstack-check",
-         "-O3");
+         "-fstack-check")
+        & Extra_Switches;
    end Compiler;
 
    package Linker is
-      for Default_Switches ("Ada") use ("-O3");
+      for Default_Switches ("Ada") use Extra_Switches;
    end Linker;
 end Natools;