basic regression test of runDockershim

- added basic regression test to ensure an error is raised in the
   case of an unconfigured runtime, and the case of asking for a docker
   runtime when compiled dockerless

Signed-off-by: Morgan Bauer <mbauer@us.ibm.com>

pkg/kubelet/kubelet_dockerless_test.go

@@ -0,0 +1,33 @@
+// +build dockerless
+
+/*
+Copyright 2020 The Kubernetes 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 kubelet_test
+
+import (
+	"testing"
+
+	"k8s.io/kubernetes/pkg/kubelet"
+	kubetypes "k8s.io/kubernetes/pkg/kubelet/types"
+)
+
+func TestPreInitRuntimeService(t *testing.T) {
+	err := kubelet.PreInitRuntimeService(nil, nil, nil, kubetypes.DockerContainerRuntime, "", "", "", "")
+	if err == nil {
+		t.Fatal("PreInitRuntimeService should fail when configured to use docker and compiled dockerless")
+	}
+}

pkg/kubelet/kubelet_test.go

@@ -1953,6 +1953,13 @@ func TestSyncPodKillPod(t *testing.T) {
 	checkPodStatus(t, kl, pod, v1.PodFailed)
 }
 
+func TestPreInitRuntimeService(t *testing.T) {
+	err := PreInitRuntimeService(nil, nil, nil, "", "", "", "", "")
+	if err == nil {
+		t.Fatal("PreInitRuntimeService should fail when not configured with a container runtime")
+	}
+}
+
 func waitForVolumeUnmount(
 	volumeManager kubeletvolume.VolumeManager,
 	pod *v1.Pod) error {