Fix nil interface{} checks

PR #1447 changed places
where we check for nil interface{} in the callback functions for
AwaitUntil to cast first. However this can result in an invalid type
conversion panic depending on how the value is returned from the
operation function. In Go, an interface var contains both a type and
value so there are 2 cases for a nil:

 1) The type is non-nil and the value is nil
 2) The type and value are nil

For #1, the interface{} var is not actually nil so checking
'if result == nil' yields false. Eg,

  var s *string
  var i interface{} = s

  if i == nil { // yields false b/c i is typed
  }

In this case, we can cast to the expected type and then check for nil.

  s := i.(*string)
  if s == nil {  // yields true
  }

For #2, the interface{} var is untyped so nil check yields true:

  var i interface{} = nil
  if i == nil { // yields true
  }

So in cases where we directly return nil from an operation function, the
nil check in the result function is valid.

The actual reason for #1447 was b/c of a nil pointer panic in
AwaitGatewaysWithStatus. This function was previously changed to call
'findGateway' and return its values. However 'findGateway' returns
*unstructured.Unstructured so now the operation function returned
a typed interface{} var. So if 'findGateway' returns a nil
*unstructured.Unstructured value, the 'result == nil' check in the
result function yields false. This resulted in the panic when 'result'
was later casted and accessed.

So we basically need to undo #1447. For AwaitGatewayWithStatus and
AwaitGatewayFullyConnected, check the error from 'findGateway' and
return a nil interface{} value.

Signed-off-by: Tom Pantelis <[email protected]>

test/e2e/framework/clusterglobalegressip.go

@@ -52,12 +52,11 @@ func AwaitAllocatedEgressIPs(client dynamic.ResourceInterface, name string) []st
 			return resGip, err
 		},
 		func(result interface{}) (bool, string, error) {
-			obj := result.(*unstructured.Unstructured)
-			if obj == nil {
+			if result == nil {
 				return false, fmt.Sprintf("Egress IP resource %q not found yet", name), nil
 			}
 
-			globalIPs := getGlobalIPs(obj)
+			globalIPs := getGlobalIPs(result.(*unstructured.Unstructured))
 			if len(globalIPs) == 0 {
 				return false, fmt.Sprintf("Egress IP resource %q exists but allocatedIPs not available yet", name), nil
 			}

test/e2e/framework/framework.go

@@ -282,11 +282,7 @@ func DetectGlobalnet() {
 	}).Namespace(TestContext.SubmarinerNamespace)
 
 	AwaitUntil("find Clusters to detect if Globalnet is enabled", func() (interface{}, error) {
-		clusters, err := clusters.List(context.TODO(), metav1.ListOptions{})
-		if apierrors.IsNotFound(err) {
-			return nil, nil //nolint:nilnil // We want to repeat but let the checker known that nothing was found.
-		}
-		return clusters, err
+		return clusters.List(context.TODO(), metav1.ListOptions{})
 	}, func(result interface{}) (bool, string, error) {
 		clusterList := result.(*unstructured.UnstructuredList)
 		if clusterList == nil || len(clusterList.Items) == 0 {
@@ -339,7 +335,7 @@ func fetchClusterIDs() {
 
 			return ds, err
 		}, func(result interface{}) (bool, string, error) {
-			if result.(*appsv1.DaemonSet) == nil {
+			if result == nil {
 				return false, "No DaemonSet found", nil
 			}
 

test/e2e/framework/gateways.go

@@ -46,24 +46,25 @@ func findGateway(cluster ClusterIndex, name string) (*unstructured.Unstructured,
 		resGw, err = gwClient.Get(context.TODO(), strings.Split(name, ".")[0], metav1.GetOptions{})
 	}
 
-	if apierrors.IsNotFound(err) {
-		return nil, nil //nolint:nilnil // We want to repeat but let the checker known that nothing was found.
-	}
-
 	return resGw, err
 }
 
 func (f *Framework) AwaitGatewayWithStatus(cluster ClusterIndex, name, status string) *unstructured.Unstructured {
 	obj := AwaitUntil(fmt.Sprintf("await Gateway on %q with status %q", name, status),
 		func() (interface{}, error) {
-			return findGateway(cluster, name)
+			gw, err := findGateway(cluster, name)
+			if apierrors.IsNotFound(err) {
+				return nil, nil //nolint:nilnil // We want to repeat but let the checker known that nothing was found.
+			}
+
+			return gw, err
 		},
 		func(result interface{}) (bool, string, error) {
-			gw := result.(*unstructured.Unstructured)
-			if gw == nil {
+			if result == nil {
 				return false, "gateway not found yet", nil
 			}
 
+			gw := result.(*unstructured.Unstructured)
 			haStatus := NestedString(gw.Object, "status", "haStatus")
 			if haStatus != status {
 				return false, fmt.Sprintf("gateway %q exists but has wrong status %q, expected %q", gw.GetName(), haStatus, status), nil
@@ -115,14 +116,19 @@ func (f *Framework) AwaitGatewayRemoved(cluster ClusterIndex, name string) {
 func (f *Framework) AwaitGatewayFullyConnected(cluster ClusterIndex, name string) *unstructured.Unstructured {
 	obj := AwaitUntil(fmt.Sprintf("await Gateway on %q with status active and connections UP", name),
 		func() (interface{}, error) {
-			return findGateway(cluster, name)
+			gw, err := findGateway(cluster, name)
+			if apierrors.IsNotFound(err) {
+				return nil, nil //nolint:nilnil // We want to repeat but let the checker known that nothing was found.
+			}
+
+			return gw, err
 		},
 		func(result interface{}) (bool, string, error) {
-			gw := result.(*unstructured.Unstructured)
-			if gw == nil {
+			if result == nil {
 				return false, "gateway not found yet", nil
 			}
 
+			gw := result.(*unstructured.Unstructured)
 			haStatus := NestedString(gw.Object, "status", "haStatus")
 			if haStatus != "active" {
 				return false, fmt.Sprintf("Gateway %q exists but not active yet",

test/e2e/framework/globalingressips.go

@@ -47,12 +47,11 @@ func (f *Framework) AwaitGlobalIngressIP(cluster ClusterIndex, name, namespace s
 				return resGip, err
 			},
 			func(result interface{}) (bool, string, error) {
-				obj := result.(*unstructured.Unstructured)
-				if obj == nil {
+				if result == nil {
 					return false, fmt.Sprintf("GlobalEgressIP %s not found yet", name), nil
 				}
 
-				globalIP := getGlobalIP(obj)
+				globalIP := getGlobalIP(result.(*unstructured.Unstructured))
 				if globalIP == "" {
 					return false, fmt.Sprintf("GlobalIngress %q exists but allocatedIP not available yet",
 						name), nil

test/e2e/framework/pods.go

@@ -116,11 +116,11 @@ func (f *Framework) AwaitUntilAnnotationOnPod(cluster ClusterIndex, annotation,
 		}
 		return pod, err
 	}, func(result interface{}) (bool, string, error) {
-		pod := result.(*v1.Pod)
-		if pod == nil {
+		if result == nil {
 			return false, "No Pod found", nil
 		}
 
+		pod := result.(*v1.Pod)
 		if pod.GetAnnotations()[annotation] == "" {
 			return false, fmt.Sprintf("Pod %q does not have annotation %q yet", podName, annotation), nil
 		}