Feature/unit tests (#53)

- Avoid relying on Clientset structure to call Kubernetes API functions.
While Clientset is a convinient "catch-all" abstraction for calling
REST API related to different Kubernetes objects, it's impossible to
mock. Replacing it wih the kubernetes.Interface would be quite
straightforward, but would require an exra level of mocked interfaces,
because of the versioning. Instead, a new interface is defined, which
contains only the objects we need of the pre-defined versions.

-  Move KubernetesClient to k8sutil package.
- Add more tests.

pkg/controller/controller.go

@@ -5,7 +5,6 @@ import (
 	"sync"
 
 	"github.com/Sirupsen/logrus"
-	"k8s.io/client-go/kubernetes"
 	"k8s.io/client-go/pkg/api/v1"
 	"k8s.io/client-go/rest"
 	"k8s.io/client-go/tools/cache"
@@ -14,12 +13,13 @@ import (
 	"github.com/zalando-incubator/postgres-operator/pkg/spec"
 	"github.com/zalando-incubator/postgres-operator/pkg/util/config"
 	"github.com/zalando-incubator/postgres-operator/pkg/util/constants"
+	"github.com/zalando-incubator/postgres-operator/pkg/util/k8sutil"
 	"github.com/zalando-incubator/postgres-operator/pkg/util/teams"
 )
 
 type Config struct {
 	RestConfig          *rest.Config
-	KubeClient          *kubernetes.Clientset
+	KubeClient          k8sutil.KubernetesClient
 	RestClient          *rest.RESTClient
 	TeamsAPIClient      *teams.API
 	InfrastructureRoles map[string]spec.PgUser
@@ -27,6 +27,7 @@ type Config struct {
 
 type Controller struct {
 	Config
+
 	opConfig *config.Config
 	logger   *logrus.Entry
 
@@ -43,7 +44,7 @@ type Controller struct {
 	lastClusterSyncTime int64
 }
 
-func New(controllerConfig *Config, operatorConfig *config.Config) *Controller {
+func NewController(controllerConfig *Config, operatorConfig *config.Config) *Controller {
 	logger := logrus.New()
 
 	if operatorConfig.DebugLogging {
@@ -82,7 +83,7 @@ func (c *Controller) initController() {
 		c.logger.Fatalf("could not register ThirdPartyResource: %v", err)
 	}
 
-	if infraRoles, err := c.getInfrastructureRoles(); err != nil {
+	if infraRoles, err := c.getInfrastructureRoles(&c.opConfig.InfrastructureRolesSecretName); err != nil {
 		c.logger.Warningf("could not get infrastructure roles: %v", err)
 	} else {
 		c.InfrastructureRoles = infraRoles