logstash-*-oss: Add passthru.tests

nixos/tests/elk.nix

···
           };
       };
 
+    passthru.elkPackages = elk;
     testScript = ''
       import json
 

pkgs/tools/misc/logstash/6.x.nix

···
 , lib, stdenv
 , fetchurl
 , makeWrapper
+, nixosTests
 , jre
 }:
 
 with lib;
 
-stdenv.mkDerivation rec {
+let this = stdenv.mkDerivation rec {
   version = elk6Version;
   name = "logstash-${optionalString (!enableUnfree) "oss-"}${version}";
 
···
     platforms   = platforms.unix;
     maintainers = with maintainers; [ wjlroe offline basvandijk ];
   };
-}
+  passthru.tests =
+    optionalAttrs (!enableUnfree) (
+      assert this.drvPath == nixosTests.elk.ELK-6.elkPackages.logstash.drvPath;
+      {
+        elk = nixosTests.elk.ELK-6;
+      }
+    );
+};
+in this

pkgs/tools/misc/logstash/7.x.nix

···
 , lib, stdenv
 , fetchurl
 , makeWrapper
+, nixosTests
 , jre
 }:
 
 with lib;
 
-stdenv.mkDerivation rec {
+let this = stdenv.mkDerivation rec {
   version = elk7Version;
   name = "logstash-${optionalString (!enableUnfree) "oss-"}${version}";
 
···
     platforms   = platforms.unix;
     maintainers = with maintainers; [ wjlroe offline basvandijk ];
   };
-}
+  passthru.tests =
+    optionalAttrs (!enableUnfree) (
+      assert this.drvPath == nixosTests.elk.ELK-7.elkPackages.logstash.drvPath;
+      {
+        elk = nixosTests.elk.ELK-7;
+      }
+    );
+};
+in this