libdbusmenu: Add meta.pkgConfigModules and test

Odd that the pkg-config names contain these numbers, but they do.

pkgs/development/libraries/libdbusmenu/default.nix

@@ -3,13 +3,16 @@
 , glib, dbus-glib, json-glib
 , gobject-introspection, vala
 , gtkVersion ? null, gtk2, gtk3
+, testers
 }:
 
-stdenv.mkDerivation rec {
+stdenv.mkDerivation (finalAttrs: {
   pname = "libdbusmenu-${if gtkVersion == null then "glib" else "gtk${gtkVersion}"}";
   version = "16.04.0";
 
-  src = fetchurl {
+  src = let
+    inherit (finalAttrs) version;
+  in fetchurl {
     url = "https://launchpad.net/dbusmenu/${lib.versions.majorMinor version}/${version}/+download/libdbusmenu-${version}.tar.gz";
     sha256 = "12l7z8dhl917iy9h02sxmpclnhkdjryn08r8i4sr8l3lrlm4mk5r";
   };
@@ -18,7 +21,11 @@ stdenv.mkDerivation rec {
 
   buildInputs = [
     glib dbus-glib json-glib
-  ] ++ lib.optional (gtkVersion != null) (if gtkVersion == "2" then gtk2 else gtk3);
+  ] ++ lib.optional (gtkVersion != null)
+    {
+      "2" = gtk2;
+      "3" = gtk3;
+    }.${gtkVersion} or (throw "unknown GTK version ${gtkVersion}");
 
   postPatch = ''
     for f in {configure,ltmain.sh,m4/libtool.m4}; do
@@ -37,6 +44,7 @@ stdenv.mkDerivation rec {
     "CFLAGS=-Wno-error"
     "--sysconfdir=/etc"
     "--localstatedir=/var"
+    # TODO use `lib.withFeatureAs`
     (if gtkVersion == null then "--disable-gtk" else "--with-gtk=${gtkVersion}")
     "--disable-scrollkeeper"
   ] ++ lib.optional (gtkVersion != "2") "--disable-dumper";
@@ -49,11 +57,17 @@ stdenv.mkDerivation rec {
     "typelibdir=${placeholder "out"}/lib/girepository-1.0"
   ];
 
+  passthru.tests.pkg-config = testers.testMetaPkgConfig finalAttrs.finalPackage;
+
   meta = with lib; {
     description = "Library for passing menu structures across DBus";
     homepage = "https://launchpad.net/dbusmenu";
     license = with licenses; [ gpl3 lgpl21 lgpl3 ];
+    pkgConfigModules = [
+      "dbusmenu-glib-0.4"
+      "dbusmenu-jsonloader-0.4"
+    ] ++ lib.optional (gtkVersion == "3") "dbusmenu-gtk${gtkVersion}-0.4";
     platforms = platforms.linux;
     maintainers = [ maintainers.msteen ];
   };
-}
+})