Failing Selenium test

default.nix

with import <nixpkgs> { };
let dependencies = rec {
  selenium = pythonPackages.selenium.overrideDerivation (args: rec {
    version = "2.48.0";
    name = "selenium-${version}";
    src = fetchurl {
      url = "https://pypi.python.org/packages/source/s/selenium/selenium-${version}.tar.gz";
      sha256 = "1n0rp6g97rg4154a48yg69vm3f4qybqwz6kqxj1xq5akjm3agp6m";
    };
    patches = [
      (builtins.toFile "fix_profiledir_permissions.patch" ''
--- a/py/selenium/webdriver/firefox/firefox_profile.py  2016-01-13 11:32:42.000000000 +0200
+++ b/py/selenium/webdriver/firefox/firefox_profile.py  2016-01-13 11:32:12.000000000 +0200
@@ -76,6 +76,7 @@
             shutil.copytree(self.profile_dir, newprof,
                             ignore=shutil.ignore_patterns("parent.lock", "lock", ".parentlock"))
             self.profile_dir = newprof
+            os.chmod(self.profile_dir, 0755)
             self._read_existing_userjs(os.path.join(self.profile_dir, "user.js"))
         self.extensionsDir = os.path.join(self.profile_dir, "extensions")
         self.userPrefs = os.path.join(self.profile_dir, "user.js")
      '')
    ];
    patchPhase = null;
    postPatch = args.patchPhase;
  });
  robotframework = pythonPackages.robotframework.overrideDerivation(args: rec {
    version = "3.0";
    name = "robotframework-${version}";
    src = fetchurl {
      url = "https://pypi.python.org/packages/source/r/robotframework/robotframework-${version}.tar.gz";
      sha256 = "11qwa1y5ph2fh0k2chmrycbnl15m23726x8ar9aagf1i63wga5nd";
    };
  });
  robotframework-selenium2library = pythonPackages.robotframework-selenium2library.overrideDerivation(args: rec {
    version = "1.7.4";
    name = "robotframework-selenium2library-${version}";
    src = fetchurl {
      url = "https://pypi.python.org/packages/source/r/robotframework-selenium2library/robotframework-selenium2library-${version}.tar.gz";
      sha256 = "004lmlryhbxd5avbqcgyq2gmscbhp57rrnad9yha8jvf3h1f6cj3";
    };
    propagatedNativeBuildInputs = [
      robotframework
      selenium
      pythonPackages.docutils
      pythonPackages.decorator
    ];
  });
  test_robot = builtins.toFile "test.robot" ''
*** Settings ***

Library  Selenium2Library
Test Teardown  Close all browsers

*** Test Cases ***

Open Firefox
    Open browser  about:  browser=firefox

Open PhantomJS
    Open browser  about:  browser=phantomjs
  '';
};

in with dependencies; stdenv.mkDerivation {
  name = "test";
  buildInputs = [
    firefox
    phantomjs
    (robotframework.overrideDerivation(args: {
      propagatedNativeBuildInputs = [ robotframework-selenium2library ];
    }))
  ];
  builder = writeText "builder.sh" ''
    source $stdenv/setup
    pybot ${test_robot}
  '';
  shellHook = ''
    echo pybot ${test_robot}
    pybot ${test_robot}
  '';
}

Not sure if it matters, but stdout from the Popen call by Selenium to open Firefox ends with:

None of the following is a 64-bit version of Xlib: /usr/lib/libX11.so.6
 /usr/lib/x86_64-linux-gnu/libX11.so.6
 /usr/lib/i386-linux-gnu/libX11.so.6
 /usr/lib64/libX11.so.6
 /usr/lib32/libX11.so.6

@garbas Found the issue. Selenium injects one of the following libs into LD_LIBARYPATH:

selenium-2.48.0-py2.7.egg/selenium/webdriver/firefox/x86/x_ignore_nofocus.so
selenium-2.48.0-py2.7.egg/selenium/webdriver/firefox/amd64/x_ignore_nofocus.so

If I build Selenium with Nix instead of Buildout, how to fix those to link properly?

Fixed by reusing expressions in nixpkgs.