expat: add some reverse dependencies to passthru.tests

pkgs/development/libraries/expat/default.nix

@@ -1,4 +1,13 @@
-{ stdenv, fetchurl, lib }:
+{ lib
+, stdenv
+, fetchurl
+# for passthru.tests
+, python3
+, perlPackages
+, haskellPackages
+, luaPackages
+, ocamlPackages
+}:
 
 # Note: this package is used for bootstrapping fetchurl, and thus
 # cannot use fetchpatch! All mutable patches (generated by GitHub or
@@ -34,6 +43,14 @@ stdenv.mkDerivation rec {
       --replace "$"'{_IMPORT_PREFIX}' $out
   '';
 
+  passthru.tests = {
+    inherit python3;
+    inherit (haskellPackages) hexpat;
+    inherit (perlPackages) XMLSAXExpat XMLParser;
+    inherit (luaPackages) luaexpat;
+    inherit (ocamlPackages) ocaml_expat;
+  };
+
   meta = with lib; {
     homepage = "https://libexpat.github.io/";
     description = "A stream-oriented XML parser library written in C";