FIX nil pointer dereference in machine ls

Signed-off-by: David Gageot <david@gageot.net>

commands/ls.go

@@ -244,13 +244,18 @@ func attemptGetHostState(h *host.Host, stateQueryChan chan<- HostListItem) {
 		hostError = ""
 	}
 
+	var swarmOptions *swarm.Options
+	if h.HostOptions != nil {
+		swarmOptions = h.HostOptions.SwarmOptions
+	}
+
 	stateQueryChan <- HostListItem{
 		Name:         h.Name,
 		Active:       isActive(currentState, url),
 		DriverName:   h.Driver.DriverName(),
 		State:        currentState,
 		URL:          url,
-		SwarmOptions: h.HostOptions.SwarmOptions,
+		SwarmOptions: swarmOptions,
 		Error:        hostError,
 	}
 }

commands/ls_test.go

@@ -455,3 +455,24 @@ func TestGetHostStateTimeout(t *testing.T) {
 
 	stateTimeoutDuration = originalTimeout
 }
+
+func TestGetHostStateError(t *testing.T) {
+	hosts := []*host.Host{
+		{
+			Name: "foo",
+			Driver: &fakedriver.Driver{
+				MockState: state.Error,
+			},
+		},
+	}
+
+	hostItems := getHostListItems(hosts)
+	hostItem := hostItems[0]
+
+	assert.Equal(t, "foo", hostItem.Name)
+	assert.Equal(t, state.Error, hostItem.State)
+	assert.Equal(t, "Driver", hostItem.DriverName)
+	assert.Empty(t, hostItem.URL)
+	assert.Equal(t, "Unable to get ip", hostItem.Error)
+	assert.Nil(t, hostItem.SwarmOptions)
+}