add spec to assert OnConnectionLost handler call

client_resolver_test.go

@@ -8,14 +8,16 @@ import (
 	"time"
 
 	mqtt "github.com/eclipse/paho.mqtt.golang"
+	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/mock"
 )
 
 func TestClient_newClient(t *testing.T) {
 	tests := []struct {
-		name          string
-		addrs         []TCPAddress
-		newClientFunc func(*mqtt.ClientOptions) mqtt.Client
+		name             string
+		addrs            []TCPAddress
+		newClientFunc    func(*mqtt.ClientOptions) mqtt.Client
+		onConnLostAssert func(*testing.T, error)
 	}{
 		{
 			name: "success_attempt_1",
@@ -92,6 +94,9 @@ func TestClient_newClient(t *testing.T) {
 					Port: 8888,
 				},
 			},
+			onConnLostAssert: func(t *testing.T, err error) {
+				assert.EqualError(t, err, "some error")
+			},
 			newClientFunc: func(o *mqtt.ClientOptions) mqtt.Client {
 				if o.Servers[0].String() != "tcp://localhost:1883" {
 					panic(o.Servers)
@@ -123,15 +128,22 @@ func TestClient_newClient(t *testing.T) {
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			c := &Client{
-				options: defaultClientOptions(),
+			opts := defaultClientOptions()
+			if tt.onConnLostAssert != nil {
+				opts.onConnectionLostHandler = func(err error) {
+					tt.onConnLostAssert(t, err)
+				}
 			}
+
+			c := &Client{options: opts}
 			newClientFunc.Store(tt.newClientFunc)
 			got := c.newClient(tt.addrs, 0)
 
 			got.(*mockClient).AssertExpectations(t)
 		})
 	}
+
+	newClientFunc.Store(mqtt.NewClient)
 }
 
 func TestClient_watchAddressUpdates(t *testing.T) {