Refactor map field handling for clientcmd.LoadFromFile

pkg/client/unversioned/clientcmd/loader.go

@@ -240,6 +240,16 @@ func LoadFromFile(filename string) (*clientcmdapi.Config, error) {
 		config.Contexts[key] = obj
 	}
 
+	if config.AuthInfos == nil {
+		config.AuthInfos = map[string]*clientcmdapi.AuthInfo{}
+	}
+	if config.Clusters == nil {
+		config.Clusters = map[string]*clientcmdapi.Cluster{}
+	}
+	if config.Contexts == nil {
+		config.Contexts = map[string]*clientcmdapi.Context{}
+	}
+
 	return config, nil
 }
 

pkg/client/unversioned/clientcmd/loader_test.go

@@ -174,6 +174,32 @@ func TestConflictingCurrentContext(t *testing.T) {
 	}
 }
 
+func TestLoadingEmptyMaps(t *testing.T) {
+	configFile, _ := ioutil.TempFile("", "")
+	defer os.Remove(configFile.Name())
+
+	mockConfig := clientcmdapi.Config{
+		CurrentContext: "any-context-value",
+	}
+
+	WriteToFile(mockConfig, configFile.Name())
+
+	config, err := LoadFromFile(configFile.Name())
+	if err != nil {
+		t.Errorf("Unexpected error: %v", err)
+	}
+
+	if config.Clusters == nil {
+		t.Error("expected config.Clusters to be non-nil")
+	}
+	if config.AuthInfos == nil {
+		t.Error("expected config.AuthInfos to be non-nil")
+	}
+	if config.Contexts == nil {
+		t.Error("expected config.Contexts to be non-nil")
+	}
+}
+
 func TestResolveRelativePaths(t *testing.T) {
 	pathResolutionConfig1 := clientcmdapi.Config{
 		AuthInfos: map[string]*clientcmdapi.AuthInfo{

pkg/kubectl/cmd/config/config.go

@@ -430,10 +430,6 @@ func getConfigFromFileOrDie(filename string) *clientcmdapi.Config {
 		return clientcmdapi.NewConfig()
 	}
 
-	if config.Clusters == nil {
-		config.Clusters = map[string]*clientcmdapi.Cluster{}
-	}
-
 	return config
 }