diff --git a/pkgs/test/kernel.nix b/pkgs/test/kernel.nix
index 2ccd188b1edb..e345d9fa207e 100644
--- a/pkgs/test/kernel.nix
+++ b/pkgs/test/kernel.nix
@@ -1,6 +1,3 @@
-# to run these tests:
-# nix-instantiate --eval --strict . -A tests.kernel-config
-#
 # make sure to use NON EXISTING kernel settings else they may conflict with
 # common-config.nix
 { lib, pkgs }:
@@ -37,37 +34,40 @@ let
     { NIXOS_FAKE_USB_DEBUG = option yes;}
   ];
 
+  failures = runTests {
+    testEasy = {
+      expr = (getConfig { NIXOS_FAKE_USB_DEBUG = yes;}).NIXOS_FAKE_USB_DEBUG;
+      expected = { tristate = "y"; optional = false; freeform = null; };
+    };
+
+    # mandatory flag should win over optional
+    testMandatoryCheck = {
+      expr = (getConfig mandatoryVsOptionalConfig).NIXOS_FAKE_USB_DEBUG.optional;
+      expected = false;
+    };
+
+    testYesWinsOverNo = {
+      expr = (getConfig mkDefaultWorksConfig)."NIXOS_TEST_BOOLEAN".tristate;
+      expected = "y";
+    };
+
+    testAllOptionalRemainOptional = {
+      expr = (getConfig allOptionalRemainOptional)."NIXOS_FAKE_USB_DEBUG".optional;
+      expected = true;
+    };
+
+    # check that freeform options are unique
+    # Should trigger
+    # > The option `settings.NIXOS_FAKE_MMC_BLOCK_MINORS.freeform' has conflicting definitions, in `<unknown-file>' and `<unknown-file>'
+    testTreeform = let
+      res = builtins.tryEval ( (getConfig freeformConfig).NIXOS_FAKE_MMC_BLOCK_MINORS.freeform);
+    in {
+      expr = res.success;
+      expected = false;
+    };
+
+  };
 in
-runTests {
-  testEasy = {
-    expr = (getConfig { NIXOS_FAKE_USB_DEBUG = yes;}).NIXOS_FAKE_USB_DEBUG;
-    expected = { tristate = "y"; optional = false; freeform = null; };
-  };
 
-  # mandatory flag should win over optional
-  testMandatoryCheck = {
-    expr = (getConfig mandatoryVsOptionalConfig).NIXOS_FAKE_USB_DEBUG.optional;
-    expected = false;
-  };
-
-  testYesWinsOverNo = {
-    expr = (getConfig mkDefaultWorksConfig)."NIXOS_TEST_BOOLEAN".tristate;
-    expected = "y";
-  };
-
-  testAllOptionalRemainOptional = {
-    expr = (getConfig allOptionalRemainOptional)."NIXOS_FAKE_USB_DEBUG".optional;
-    expected = true;
-  };
-
-  # check that freeform options are unique
-  # Should trigger
-  # > The option `settings.NIXOS_FAKE_MMC_BLOCK_MINORS.freeform' has conflicting definitions, in `<unknown-file>' and `<unknown-file>'
-  testTreeform = let
-    res = builtins.tryEval ( (getConfig freeformConfig).NIXOS_FAKE_MMC_BLOCK_MINORS.freeform);
-  in {
-    expr = res.success;
-    expected = false;
-  };
-
-}
+lib.optional (failures != [])
+  (throw "The following kernel unit tests failed: ${lib.generators.toPretty {} failures}")
diff --git a/pkgs/test/systemd/nixos/default.nix b/pkgs/test/systemd/nixos/default.nix
index e45399b63516..37b42ea7ae27 100644
--- a/pkgs/test/systemd/nixos/default.nix
+++ b/pkgs/test/systemd/nixos/default.nix
@@ -1,37 +1,42 @@
 { pkgs, lib, stdenv, ... }:
 
-lib.runTests {
-  # Merging two non-list definitions must still result in an error
-  # about a conflicting definition.
-  test-unitOption-merging-non-lists-conflict =
-    let nixos = pkgs.nixos {
-        system.stateVersion = lib.trivial.release;
-        systemd.services.systemd-test-nixos = {
-          serviceConfig = lib.mkMerge [
-            { StateDirectory = "foo"; }
-            { StateDirectory = "bar"; }
-          ];
+let
+  failures = lib.runTests {
+    # Merging two non-list definitions must still result in an error
+    # about a conflicting definition.
+    test-unitOption-merging-non-lists-conflict =
+      let nixos = pkgs.nixos {
+          system.stateVersion = lib.trivial.release;
+          systemd.services.systemd-test-nixos = {
+            serviceConfig = lib.mkMerge [
+              { StateDirectory = "foo"; }
+              { StateDirectory = "bar"; }
+            ];
+          };
         };
-      };
-    in {
-    expr = (builtins.tryEval (nixos.config.systemd.services.systemd-test-nixos.serviceConfig.StateDirectory)).success;
-    expected = false;
-  };
+      in {
+      expr = (builtins.tryEval (nixos.config.systemd.services.systemd-test-nixos.serviceConfig.StateDirectory)).success;
+      expected = false;
+    };
 
-  # Merging must lift non-list definitions to a list
-  # if at least one of them is a list.
-  test-unitOption-merging-list-non-list-append =
-    let nixos = pkgs.nixos {
-        system.stateVersion = lib.trivial.release;
-        systemd.services.systemd-test-nixos = {
-          serviceConfig = lib.mkMerge [
-            { StateDirectory = "foo"; }
-            { StateDirectory = ["bar"]; }
-          ];
+    # Merging must lift non-list definitions to a list
+    # if at least one of them is a list.
+    test-unitOption-merging-list-non-list-append =
+      let nixos = pkgs.nixos {
+          system.stateVersion = lib.trivial.release;
+          systemd.services.systemd-test-nixos = {
+            serviceConfig = lib.mkMerge [
+              { StateDirectory = "foo"; }
+              { StateDirectory = ["bar"]; }
+            ];
+          };
         };
-      };
-    in {
-    expr = nixos.config.systemd.services.systemd-test-nixos.serviceConfig.StateDirectory;
-    expected = [ "foo" "bar" ];
+      in {
+      expr = nixos.config.systemd.services.systemd-test-nixos.serviceConfig.StateDirectory;
+      expected = [ "foo" "bar" ];
+    };
   };
-}
+in
+
+lib.optional (failures != [])
+  (throw "The following systemd unit tests failed: ${lib.generators.toPretty {} failures}")