Add unit test.

Signed-off-by: Lantao Liu <lantaol@google.com>

pkg/server/testing/fake_execution_client.go

@@ -51,7 +51,10 @@ type EventClient struct {
 
 // Recv is a test implementation of Recv
 func (cli *EventClient) Recv() (*container.Event, error) {
-	event := <-cli.Events
+	event, ok := <-cli.Events
+	if !ok {
+		return nil, fmt.Errorf("event channel closed")
+	}
 	return event, nil
 }
 
@@ -76,6 +79,18 @@ func NewFakeExecutionClient() *FakeExecutionClient {
 	}
 }
 
+// Stop the fake execution service. Needed when event is enabled.
+func (f *FakeExecutionClient) Stop() {
+	if f.eventsQueue != nil {
+		close(f.eventsQueue)
+	}
+	f.Lock()
+	defer f.Unlock()
+	for _, client := range f.eventClients {
+		close(client.Events)
+	}
+}
+
 // WithEvents setup events publisher for FakeExecutionClient
 func (f *FakeExecutionClient) WithEvents() *FakeExecutionClient {
 	f.eventsQueue = make(chan *container.Event, 1024)
@@ -154,6 +169,13 @@ func (f *FakeExecutionClient) GetCalledNames() []string {
 	return names
 }
 
+// ClearCalls clear all call detail.
+func (f *FakeExecutionClient) ClearCalls() {
+	f.Lock()
+	defer f.Unlock()
+	f.called = []CalledDetail{}
+}
+
 // GetCalledDetails get detail of each call.
 func (f *FakeExecutionClient) GetCalledDetails() []CalledDetail {
 	f.Lock()