diff --git a/cluster/tools/kartongips/utils/nativefuncs_test.go b/cluster/tools/kartongips/utils/nativefuncs_test.go
new file mode 100644
index 0000000..cb98f10
--- /dev/null
+++ b/cluster/tools/kartongips/utils/nativefuncs_test.go
@@ -0,0 +1,104 @@
+// Copyright 2017 The kubecfg authors
+//
+//
+//    Licensed under the Apache License, Version 2.0 (the "License");
+//    you may not use this file except in compliance with the License.
+//    You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+//    Unless required by applicable law or agreed to in writing, software
+//    distributed under the License is distributed on an "AS IS" BASIS,
+//    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+//    See the License for the specific language governing permissions and
+//    limitations under the License.
+
+package utils
+
+import (
+	"testing"
+
+	jsonnet "github.com/google/go-jsonnet"
+)
+
+// check there is no err, and a == b.
+func check(t *testing.T, err error, actual, expected string) {
+	if err != nil {
+		t.Errorf("Expected %q, got error: %q", expected, err.Error())
+	} else if actual != expected {
+		t.Errorf("Expected %q, got %q", expected, actual)
+	}
+}
+
+func TestParseJson(t *testing.T) {
+	vm := jsonnet.MakeVM()
+	RegisterNativeFuncs(vm, NewIdentityResolver())
+
+	_, err := vm.EvaluateSnippet("failtest", `std.native("parseJson")("barf{")`)
+	if err == nil {
+		t.Errorf("parseJson succeeded on invalid json")
+	}
+
+	x, err := vm.EvaluateSnippet("test", `std.native("parseJson")("null")`)
+	check(t, err, x, "null\n")
+
+	x, err = vm.EvaluateSnippet("test", `
+    local a = std.native("parseJson")('{"foo": 3, "bar": 4}');
+    a.foo + a.bar`)
+	check(t, err, x, "7\n")
+}
+
+func TestParseYaml(t *testing.T) {
+	vm := jsonnet.MakeVM()
+	RegisterNativeFuncs(vm, NewIdentityResolver())
+
+	_, err := vm.EvaluateSnippet("failtest", `std.native("parseYaml")("[barf")`)
+	if err == nil {
+		t.Errorf("parseYaml succeeded on invalid yaml")
+	}
+
+	x, err := vm.EvaluateSnippet("test", `std.native("parseYaml")("")`)
+	check(t, err, x, "[ ]\n")
+
+	x, err = vm.EvaluateSnippet("test", `
+    local a = std.native("parseYaml")("foo:\n- 3\n- 4\n")[0];
+    a.foo[0] + a.foo[1]`)
+	check(t, err, x, "7\n")
+
+	x, err = vm.EvaluateSnippet("test", `
+    local a = std.native("parseYaml")("---\nhello\n---\nworld");
+    a[0] + a[1]`)
+	check(t, err, x, "\"helloworld\"\n")
+}
+
+func TestRegexMatch(t *testing.T) {
+	vm := jsonnet.MakeVM()
+	RegisterNativeFuncs(vm, NewIdentityResolver())
+
+	_, err := vm.EvaluateSnippet("failtest", `std.native("regexMatch")("[f", "foo")`)
+	if err == nil {
+		t.Errorf("regexMatch succeeded with invalid regex")
+	}
+
+	x, err := vm.EvaluateSnippet("test", `std.native("regexMatch")("foo.*", "seafood")`)
+	check(t, err, x, "true\n")
+
+	x, err = vm.EvaluateSnippet("test", `std.native("regexMatch")("bar.*", "seafood")`)
+	check(t, err, x, "false\n")
+}
+
+func TestRegexSubst(t *testing.T) {
+	vm := jsonnet.MakeVM()
+	RegisterNativeFuncs(vm, NewIdentityResolver())
+
+	_, err := vm.EvaluateSnippet("failtest", `std.native("regexSubst")("[f",s "foo", "bar")`)
+	if err == nil {
+		t.Errorf("regexSubst succeeded with invalid regex")
+	}
+
+	x, err := vm.EvaluateSnippet("test", `std.native("regexSubst")("a(x*)b", "-ab-axxb-", "T")`)
+	check(t, err, x, "\"-T-T-\"\n")
+
+	x, err = vm.EvaluateSnippet("test", `std.native("regexSubst")("a(x*)b", "-ab-axxb-", "${1}W")`)
+	check(t, err, x, "\"-W-xxW-\"\n")
+}