regtests: Fix OS mixup in 0229_deep_resources

test.py and deep_res.adb both use the OS environment variable to determine
how long path components should be, since 50 is too long for Windows hosts.
However, in a Windows-hosted cross-Linux test, test.py will get one answer,
and deep_res.adb another.

Fix this by replacing the run-time check in deep_res.adb by a build-time
config file selection.  Let test_support.build() set the scenario variable
to make gprbuild pick the correct file.

Amend the test.py check for homogeneity.  Change the discriminant, since
"NT" is not set when targeting Linux.

TN: eng/toolchain/aws#11

Author: peniblec

regtests/0229_deep_resources/config_linux.ads

@@ -0,0 +1,3 @@
+package Config is
+   Path_Component_Length : Natural := 50;
+end Config;

regtests/0229_deep_resources/config_windows.ads

@@ -0,0 +1,3 @@
+package Config is
+   Path_Component_Length : Natural := 20;
+end Config;

regtests/0229_deep_resources/deep_res.adb

@@ -23,6 +23,7 @@ with Ada.Text_IO;
 with AWS.Resources.Embedded;
 with AWS.Utils;
 
+with Config;
 with rdemo;
 
 procedure Deep_Res is
@@ -42,13 +43,7 @@ procedure Deep_Res is
    function Gen (C : Character) return String is
       use Ada.Strings.Fixed;
    begin
-      if Environment_Variables.Exists ("OS")
-        and then Environment_Variables.Value ("OS") = "Windows_NT"
-      then
-         return 20 * C;
-      else
-         return 50 * C;
-      end if;
+      return Config.Path_Component_Length * C;
    end Gen;
 
    ----------

regtests/0229_deep_resources/deep_res.gpr

@@ -27,4 +27,16 @@ project Deep_Res is
       for Default_Switches ("Ada") use ("-gnaty", "-gnatwe");
    end Compiler;
 
+   type OS_Kind is ("linux", "windows");
+   Host_OS : OS_Kind := external ("Host_OS");
+
+   package Naming is
+      case Host_OS is
+         when "linux" =>
+            for Specification ("Config") use "config_linux.ads";
+         when "windows" =>
+            for Specification ("Config") use "config_windows.ads";
+      end case;
+   end Naming;
+
 end Deep_Res;

regtests/0229_deep_resources/test.opt

@@ -1,2 +1,2 @@
 vxworks DEAD "require awsres"
-NT OUT test-nt.out
+windows-host OUT test-nt.out

regtests/0229_deep_resources/test.py

@@ -1,13 +1,15 @@
 from test_support import *
 import os
 
+from e3.env import Env
+
 def create_res(name,content):
     f=open(name,'w')
     f.write(content)
     f.close();
 
 def gen(c):
-    if os.environ.get("OS") == "Windows_NT":
+    if Env().host.os.name == "windows":
         return c * 20;
     else:
         return c * 50;

regtests/test_support.py

@@ -57,7 +57,7 @@ def tail(infile_name, outfile_name, nb_line):
 
 def build(prj):
     """Compile a project with gprbuild"""
-    cmd = ["gprbuild"]
+    cmd = ["gprbuild", f"-XHost_OS={Env().host.os.name}"]
     if Env().is_cross:
         cmd.append("--target=" + Env().target.triplet)
         if Env().target.os.name.startswith("vxworks"):