more tests for ini.nix and some fixes too

nixos/lib/ini.nix

 { pkgs ? import <nixpkgs> { } }:
 let lib = pkgs.lib;
 in rec {
+  # Get the .ini-file-appropriate string representation of a simple value.
+  #
+  # toINIString "hello" -> "hello"
+  # toINIString true -> "true"
+  toINIString = v:
+    if builtins.isBool v then builtins.toJSON v
+    else builtins.toString v;
+
   # Map a function over an attrset and concatenate the string results.
   #
   # concatMapAttrsToList (n: v: "${n} = ${v}\n") { a = "b"; c = "d"; } -> "a = b\nc = d\n"
@@ -11,7 +19,7 @@ in rec {
   #
   # oneConfigItemText "foo" "bar" -> "foo = bar\n"
   oneConfigItemText = name: value:
-    "${name} = ${builtins.toString value}\n";
+    "${name} = ${toINIString value}\n";
 
   # Generate all lines of configuration defining all items in one section.
   #
@@ -25,8 +33,7 @@ in rec {
   # oneConfigSectionText "foo" { bar = "baz"; } -> "[foo]\nbar = baz\n"
   oneConfigSectionText = name: value: ''
     [${name}]
-    ${allConfigItemsText value}
-    '';
+    ${allConfigItemsText value}'';
 
   # Generate all lines of configuration for all sections, headers
   # and items included.

nixos/lib/tests/test_ini.nix

-let
-  pkgs = import <nixpkgs> { };
-  ini = import ../ini.nix { inherit pkgs; };
-in
-pkgs.lib.runTests
+ini:
 { test_empty =
-  { name = "test_empty";
-    expected = "";
+  { expected = "";
     expr = ini.allConfigSectionsText { };
   };
 
-  test_one_section =
-  { name = "test_one_empty_section";
-    expected = ''
+  test_one_empty_section =
+  { expected = ''
     [foo]
-
     '';
     expr = ini.allConfigSectionsText { foo = { }; };
   };
+
+  test_one_section_one_item =
+  { expected = ''
+    [foo]
+    bar = baz
+    '';
+    expr = ini.allConfigSectionsText { foo = { bar = "baz"; }; };
+  };
+
+  test_one_section_two_items =
+  { expected = ''
+    [foo]
+    bar = baz
+    foobar = quux
+    '';
+    expr = ini.allConfigSectionsText { foo = { bar = "baz"; foobar = "quux"; }; };
+  };
+
+  test_two_sections =
+  { expected = ''
+    [alpha]
+    beta = gamma
+    [foo]
+    bar = baz
+    foobar = quux
+    '';
+    expr = ini.allConfigSectionsText
+    { foo = { bar = "baz"; foobar = "quux"; };
+      alpha = { beta = "gamma"; };
+    };
+  };
+
+  test_true =
+  { expected = "x = true\n";
+    expr = ini.oneConfigItemText "x" true;
+  };
+
+  test_false =
+  { expected = "x = false\n";
+    expr = ini.oneConfigItemText "x" false;
+  };
+
+  test_integer =
+  { expected = "x = 12345\n";
+    expr = ini.oneConfigItemText "x" 12345;
+  };
 }