solr: specify NixOS test

pkgs/servers/search/solr/default.nix

@@ -1,4 +1,4 @@
-{ stdenv, fetchurl, jre, makeWrapper }:
+{ stdenv, fetchurl, jre, makeWrapper, nixosTests }:
 
 stdenv.mkDerivation rec {
   pname = "solr";
@@ -24,6 +24,10 @@ stdenv.mkDerivation rec {
     wrapProgram $out/bin/post --set JAVA_HOME "${jre}"
   '';
 
+  passthru.tests = {
+    inherit (nixosTests) solr;
+  };
+
   meta = with stdenv.lib; {
     homepage = "https://lucene.apache.org/solr/";
     description = "Open source enterprise search platform from the Apache Lucene project";