Additional error states

1. Add additional error states, including EPMissingPod, PodNotFound, and
   NodeNotFound
2. Update error from syncInternalImpl and add setErrorState logging
3. Add TestValidateEndpointBatch and TestValidateEndpointFields to test
   if the existing error states are triggered as expected.

pkg/neg/syncers/transaction_test.go

@@ -18,15 +18,19 @@ package syncers
 
 import (
 	context2 "context"
+	"errors"
 	"fmt"
 	"net"
+	"net/http"
 	"reflect"
 	"strconv"
 	"testing"
 	"time"
 
 	"github.com/GoogleCloudPlatform/k8s-cloud-provider/pkg/cloud"
 	"github.com/GoogleCloudPlatform/k8s-cloud-provider/pkg/cloud/meta"
+	"google.golang.org/api/compute/v1"
+	"google.golang.org/api/googleapi"
 	corev1 "k8s.io/api/core/v1"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	v1 "k8s.io/apimachinery/pkg/apis/meta/v1"
@@ -1388,6 +1392,66 @@ func TestUnknownNodes(t *testing.T) {
 	}
 }
 
+func TestValidateEndpointBatch(t *testing.T) {
+	fakeGCE := gce.NewFakeGCECloud(gce.DefaultTestClusterValues())
+	fakeCloud := negtypes.NewAdapter(fakeGCE)
+	zone := "us-central1-a"
+	networkEndpoints := []*composite.NetworkEndpoint{}
+
+	testCases := []struct {
+		desc              string
+		returnError       error
+		endpointOperation transactionOp
+		expect            error
+	}{
+		{
+			desc:              "Not googleapi error",
+			returnError:       errors.New("Not googleapi.Error"),
+			endpointOperation: attachOp,
+			expect:            negtypes.ErrInvalidAPIResponse,
+		},
+		{
+			desc: "Server error, status code 500",
+			returnError: &googleapi.Error{
+				Code: http.StatusInternalServerError,
+			},
+			endpointOperation: attachOp,
+			expect:            nil,
+		},
+		{
+			desc: "Invalid endpoint batch for endpoint attach, status code 400",
+			returnError: &googleapi.Error{
+				Code: http.StatusBadRequest,
+			},
+			endpointOperation: attachOp,
+			expect:            negtypes.ErrInvalidEPAttach,
+		},
+		{
+			desc: "Invalid endpoint batch for endpoint detach, status code 400",
+			returnError: &googleapi.Error{
+				Code: http.StatusBadRequest,
+			},
+			endpointOperation: detachOp,
+			expect:            negtypes.ErrInvalidEPDetach,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.desc, func(t *testing.T) {
+			mockGCE := fakeGCE.Compute().(*cloud.MockGCE)
+			mockGCE.MockNetworkEndpointGroups.AttachNetworkEndpointsHook = func(ctx context2.Context, key *meta.Key, arg0 *compute.NetworkEndpointGroupsAttachEndpointsRequest, neg *cloud.MockNetworkEndpointGroups) error {
+				return tc.returnError
+			}
+			_, transactionSyncer := newTestTransactionSyncer(fakeCloud, negtypes.VmIpPortEndpointType, false)
+
+			err := transactionSyncer.cloud.AttachNetworkEndpoints(transactionSyncer.NegSyncerKey.NegName, zone, networkEndpoints, transactionSyncer.NegSyncerKey.GetAPIVersion())
+			if got := transactionSyncer.ValidateEndpointBatch(err, tc.endpointOperation); !errors.Is(got, tc.expect) {
+				t.Errorf("ValidateEndpointBatch() = %t, expected %t", got, tc.expect)
+			}
+		})
+	}
+}
+
 func newL4ILBTestTransactionSyncer(fakeGCE negtypes.NetworkEndpointGroupCloud, mode negtypes.EndpointsCalculatorMode) (negtypes.NegSyncer, *transactionSyncer) {
 	negsyncer, ts := newTestTransactionSyncer(fakeGCE, negtypes.VmIpEndpointType, false)
 	ts.endpointsCalculator = GetEndpointsCalculator(ts.nodeLister, ts.podLister, ts.zoneGetter, ts.NegSyncerKey, mode, klog.TODO(), negtypes.PodLabelPropagationConfig{})