diff --git a/nixos/lib/build-vms.nix b/nixos/lib/build-vms.nix
index 933f8139249..024f4414ebe 100644
--- a/nixos/lib/build-vms.nix
+++ b/nixos/lib/build-vms.nix
@@ -1,4 +1,13 @@
-{ system, pkgs, minimal ? false, config ? {} }:
+{ system
+, # Use a minimal kernel?
+  minimal ? false
+, # Ignored
+  config ? null
+  # Nixpkgs, for qemu, lib and more
+, pkgs
+, # NixOS configuration to add to the VMs
+  extraConfigurations ? []
+}:
 
 with pkgs.lib;
 with import ../lib/qemu-flags.nix { inherit pkgs; };
@@ -28,7 +37,8 @@ rec {
           ../modules/testing/test-instrumentation.nix # !!! should only get added for automated test runs
           { key = "no-manual"; documentation.nixos.enable = false; }
           { key = "qemu"; system.build.qemu = qemu; }
-        ] ++ optional minimal ../modules/testing/minimal-kernel.nix;
+        ] ++ optional minimal ../modules/testing/minimal-kernel.nix
+          ++ extraConfigurations;
       extraArgs = { inherit nodes; };
     };
 
diff --git a/nixos/lib/testing.nix b/nixos/lib/testing.nix
index f90fc9f7df0..690f7dfd5fa 100644
--- a/nixos/lib/testing.nix
+++ b/nixos/lib/testing.nix
@@ -1,6 +1,13 @@
-{ system, pkgs, minimal ? false, config ? {} }:
+{ system
+, pkgs
+  # Use a minimal kernel?
+, minimal ? false
+  # Ignored
+, config ? null
+  # Modules to add to each VM
+, extraConfigurations ? [] }:
 
-with import ./build-vms.nix { inherit system pkgs minimal config; };
+with import ./build-vms.nix { inherit system pkgs minimal extraConfigurations; };
 with pkgs;
 
 let
diff --git a/pkgs/test/default.nix b/pkgs/test/default.nix
index 24948ce9aa4..9315595f8ec 100644
--- a/pkgs/test/default.nix
+++ b/pkgs/test/default.nix
@@ -30,5 +30,7 @@ with pkgs;
 
   cross = callPackage ./cross {};
 
+  nixos-functions = callPackage ./nixos-functions {};
+
   patch-shebangs = callPackage ./patch-shebangs {};
 }
diff --git a/pkgs/test/nixos-functions/default.nix b/pkgs/test/nixos-functions/default.nix
new file mode 100644
index 00000000000..c8f7122006f
--- /dev/null
+++ b/pkgs/test/nixos-functions/default.nix
@@ -0,0 +1,33 @@
+/*
+
+This file is a test that makes sure that the `pkgs.nixos` and
+`pkgs.nixosTest` functions work. It's far from a perfect test suite,
+but better than not checking them at all on hydra.
+
+To run this test:
+
+    nixpkgs$ nix-build -A tests.nixos-functions
+
+ */
+{ pkgs, lib, stdenv, ... }:
+
+lib.optionalAttrs stdenv.hostPlatform.isLinux (
+  pkgs.recurseIntoAttrs {
+
+    nixos-test = (pkgs.nixos {
+      boot.loader.grub.enable = false;
+      fileSystems."/".device = "/dev/null";
+    }).toplevel;
+
+    nixosTest-test = pkgs.nixosTest ({ lib, pkgs, ... }: {
+      name = "nixosTest-test";
+      machine = { pkgs, ... }: {
+        environment.systemPackages = [ pkgs.hello ];
+      };
+      testScript = ''
+        $machine->succeed("hello");
+      '';
+    });
+
+  }
+)
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index fe367ebbb32..b5a45a02084 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -22219,6 +22219,61 @@ with pkgs;
                 );
     }).config.system.build;
 
+
+  /*
+   * Run a NixOS VM network test using this evaluation of Nixpkgs.
+   *
+   * It is mostly equivalent to `import ./make-test.nix` from the
+   * NixOS manual[1], except that your `pkgs` will be used instead of
+   * letting NixOS invoke Nixpkgs again. If a test machine needs to
+   * set NixOS options under `nixpkgs`, it must set only the
+   * `nixpkgs.pkgs` option. For the details, see the Nixpkgs
+   * `pkgs.nixos` documentation.
+   *
+   * Parameter:
+   *   A NixOS VM test network, or path to it. Example:
+   *
+   *      { lib, ... }:
+   *      { name = "my-test";
+   *        nodes = {
+   *          machine-1 = someNixOSConfiguration;
+   *          machine-2 = ...;
+   *        }
+   *      }
+   *
+   * Result:
+   *   A derivation that runs the VM test.
+   *
+   * [1]: For writing NixOS tests, see
+   *      https://nixos.org/nixos/manual/index.html#sec-nixos-tests
+   */
+  nixosTest =
+    let
+      /* The nixos/lib/testing.nix module, preapplied with arguments that
+       * make sense for this evaluation of Nixpkgs.
+       */
+      nixosTesting =
+        (import ../../nixos/lib/testing.nix {
+          inherit (pkgs.stdenv.hostPlatform) system;
+          inherit pkgs;
+          extraConfigurations = [(
+            { lib, ... }: {
+              config.nixpkgs.pkgs = lib.mkDefault pkgs;
+            }
+          )];
+        });
+    in
+      test:
+        let
+          loadedTest = if builtins.typeOf test == "path"
+                       then import test
+                       else test;
+          calledTest = if pkgs.lib.isFunction loadedTest
+                       then callPackage loadedTest {}
+                       else loadedTest;
+        in
+          nixosTesting.makeTest calledTest;
+
   nixui = callPackage ../tools/package-management/nixui { node_webkit = nwjs_0_12; };
 
   nixdoc = callPackage ../tools/nix/nixdoc {};