add test code for kubectl config set

pkg/kubectl/cmd/config/BUILD

@@ -56,6 +56,7 @@ go_test(
         "get_clusters_test.go",
         "get_contexts_test.go",
         "navigation_step_parser_test.go",
+        "set_test.go",
         "unset_test.go",
         "use_context_test.go",
     ],

pkg/kubectl/cmd/config/set_test.go

@@ -0,0 +1,88 @@
+/*
+Copyright 2017 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 config
+
+import (
+	"bytes"
+	"io/ioutil"
+	"os"
+	"testing"
+
+	"reflect"
+
+	"k8s.io/client-go/tools/clientcmd"
+	clientcmdapi "k8s.io/client-go/tools/clientcmd/api"
+)
+
+type setConfigTest struct {
+	description    string
+	config         clientcmdapi.Config
+	args           []string
+	expected       string
+	expectedConfig clientcmdapi.Config
+}
+
+func TestSetConfigCurrentContext(t *testing.T) {
+	conf := clientcmdapi.Config{
+		Kind:           "Config",
+		APIVersion:     "v1",
+		CurrentContext: "minikube",
+	}
+	expectedConfig := *clientcmdapi.NewConfig()
+	expectedConfig.CurrentContext = "my-cluster"
+	test := setConfigTest{
+		description:    "Testing for kubectl config set current-context",
+		config:         conf,
+		args:           []string{"current-context", "my-cluster"},
+		expected:       `Property "current-context" set.` + "\n",
+		expectedConfig: expectedConfig,
+	}
+	test.run(t)
+}
+
+func (test setConfigTest) run(t *testing.T) {
+	fakeKubeFile, err := ioutil.TempFile("", "")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	defer os.Remove(fakeKubeFile.Name())
+	err = clientcmd.WriteToFile(test.config, fakeKubeFile.Name())
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	pathOptions := clientcmd.NewDefaultPathOptions()
+	pathOptions.GlobalFile = fakeKubeFile.Name()
+	pathOptions.EnvVar = ""
+	buf := bytes.NewBuffer([]byte{})
+	cmd := NewCmdConfigSet(buf, pathOptions)
+	cmd.SetArgs(test.args)
+	if err := cmd.Execute(); err != nil {
+		t.Fatalf("unexpected error executing command: %v", err)
+	}
+	config, err := clientcmd.LoadFromFile(fakeKubeFile.Name())
+	if err != nil {
+		t.Fatalf("unexpected error loading kubeconfig file: %v", err)
+	}
+	if len(test.expected) != 0 {
+		if buf.String() != test.expected {
+			t.Errorf("Failded in:%q\n expected %v\n but got %v", test.description, test.expected, buf.String())
+		}
+	}
+	if !reflect.DeepEqual(*config, test.expectedConfig) {
+		t.Errorf("Failed in: %q\n expected %v\n but got %v", test.description, *config, test.expectedConfig)
+	}
+}