Stronger typing for validation ErrorList

examples/examples_test.go

@@ -33,12 +33,13 @@ import (
 	expvalidation "k8s.io/kubernetes/pkg/apis/extensions/validation"
 	"k8s.io/kubernetes/pkg/capabilities"
 	"k8s.io/kubernetes/pkg/runtime"
+	utilvalidation "k8s.io/kubernetes/pkg/util/validation"
 	"k8s.io/kubernetes/pkg/util/yaml"
 	schedulerapi "k8s.io/kubernetes/plugin/pkg/scheduler/api"
 	schedulerapilatest "k8s.io/kubernetes/plugin/pkg/scheduler/api/latest"
 )
 
-func validateObject(obj runtime.Object) (errors []error) {
+func validateObject(obj runtime.Object) (errors utilvalidation.ErrorList) {
 	switch t := obj.(type) {
 	case *api.ReplicationController:
 		if t.Namespace == "" {
@@ -122,7 +123,7 @@ func validateObject(obj runtime.Object) (errors []error) {
 		}
 		errors = expvalidation.ValidateDaemonSet(t)
 	default:
-		return []error{fmt.Errorf("no validation defined for %#v", obj)}
+		return utilvalidation.ErrorList{utilvalidation.NewInternalError("", fmt.Errorf("no validation defined for %#v", obj))}
 	}
 	return errors
 }

pkg/api/errors/errors.go

@@ -24,7 +24,6 @@ import (
 
 	"k8s.io/kubernetes/pkg/api/unversioned"
 	"k8s.io/kubernetes/pkg/runtime"
-	utilerrors "k8s.io/kubernetes/pkg/util/errors"
 	"k8s.io/kubernetes/pkg/util/validation"
 )
 
@@ -162,13 +161,12 @@ func NewConflict(kind, name string, err error) error {
 func NewInvalid(kind, name string, errs validation.ErrorList) error {
 	causes := make([]unversioned.StatusCause, 0, len(errs))
 	for i := range errs {
-		if err, ok := errs[i].(*validation.Error); ok {
-			causes = append(causes, unversioned.StatusCause{
-				Type:    unversioned.CauseType(err.Type),
-				Message: err.ErrorBody(),
-				Field:   err.Field,
-			})
-		}
+		err := errs[i]
+		causes = append(causes, unversioned.StatusCause{
+			Type:    unversioned.CauseType(err.Type),
+			Message: err.ErrorBody(),
+			Field:   err.Field,
+		})
 	}
 	return &StatusError{unversioned.Status{
 		Status: unversioned.StatusFailure,
@@ -179,7 +177,7 @@ func NewInvalid(kind, name string, errs validation.ErrorList) error {
 			Name:   name,
 			Causes: causes,
 		},
-		Message: fmt.Sprintf("%s %q is invalid: %v", kind, name, utilerrors.NewAggregate(errs)),
+		Message: fmt.Sprintf("%s %q is invalid: %v", kind, name, errs.ToAggregate()),
 	}}
 }
 

pkg/api/rest/update.go

@@ -57,11 +57,11 @@ func validateCommonFields(obj, old runtime.Object) utilvalidation.ErrorList {
 	allErrs := utilvalidation.ErrorList{}
 	objectMeta, err := api.ObjectMetaFor(obj)
 	if err != nil {
-		return append(allErrs, errors.NewInternalError(err))
+		return append(allErrs, utilvalidation.NewInternalError("metadata", err))
 	}
 	oldObjectMeta, err := api.ObjectMetaFor(old)
 	if err != nil {
-		return append(allErrs, errors.NewInternalError(err))
+		return append(allErrs, utilvalidation.NewInternalError("metadata", err))
 	}
 	allErrs = append(allErrs, validation.ValidateObjectMetaUpdate(objectMeta, oldObjectMeta)...)
 

pkg/api/validation/schema.go

@@ -27,7 +27,6 @@ import (
 	"github.com/golang/glog"
 	apiutil "k8s.io/kubernetes/pkg/api/util"
 	utilerrors "k8s.io/kubernetes/pkg/util/errors"
-	"k8s.io/kubernetes/pkg/util/validation"
 	"k8s.io/kubernetes/pkg/util/yaml"
 )
 
@@ -67,11 +66,11 @@ func NewSwaggerSchemaFromBytes(data []byte) (Schema, error) {
 	return schema, nil
 }
 
-// validateList unpack a list and validate every item in the list.
+// validateList unpacks a list and validate every item in the list.
 // It return nil if every item is ok.
 // Otherwise it return an error list contain errors of every item.
-func (s *SwaggerSchema) validateList(obj map[string]interface{}) validation.ErrorList {
-	allErrs := validation.ErrorList{}
+func (s *SwaggerSchema) validateList(obj map[string]interface{}) []error {
+	allErrs := []error{}
 	items, exists := obj["items"]
 	if !exists {
 		return append(allErrs, fmt.Errorf("no items field in %#v", obj))
@@ -160,8 +159,8 @@ func (s *SwaggerSchema) ValidateBytes(data []byte) error {
 	return utilerrors.NewAggregate(allErrs)
 }
 
-func (s *SwaggerSchema) ValidateObject(obj interface{}, fieldName, typeName string) validation.ErrorList {
-	allErrs := validation.ErrorList{}
+func (s *SwaggerSchema) ValidateObject(obj interface{}, fieldName, typeName string) []error {
+	allErrs := []error{}
 	models := s.api.Models
 	model, ok := models.At(typeName)
 	if !ok {
@@ -215,7 +214,7 @@ func (s *SwaggerSchema) ValidateObject(obj interface{}, fieldName, typeName stri
 // This matches type name in the swagger spec, such as "v1.Binding".
 var versionRegexp = regexp.MustCompile(`^v.+\..*`)
 
-func (s *SwaggerSchema) validateField(value interface{}, fieldName, fieldType string, fieldDetails *swagger.ModelProperty) validation.ErrorList {
+func (s *SwaggerSchema) validateField(value interface{}, fieldName, fieldType string, fieldDetails *swagger.ModelProperty) []error {
 	// TODO: caesarxuchao: because we have multiple group/versions and objects
 	// may reference objects in other group, the commented out way of checking
 	// if a filedType is a type defined by us is outdated. We use a hacky way
@@ -229,7 +228,7 @@ func (s *SwaggerSchema) validateField(value interface{}, fieldName, fieldType st
 		// if strings.HasPrefix(fieldType, apiVersion) {
 		return s.ValidateObject(value, fieldName, fieldType)
 	}
-	allErrs := validation.ErrorList{}
+	allErrs := []error{}
 	switch fieldType {
 	case "string":
 		// Be loose about what we accept for 'string' since we use IntOrString in a couple of places

pkg/api/validation/validation.go

@@ -1480,7 +1480,7 @@ func ValidateNodeUpdate(node, oldNode *api.Node) validation.ErrorList {
 	addresses := make(map[api.NodeAddress]bool)
 	for _, address := range node.Status.Addresses {
 		if _, ok := addresses[address]; ok {
-			allErrs = append(allErrs, fmt.Errorf("duplicate node addresses found"))
+			allErrs = append(allErrs, validation.NewFieldDuplicate("addresses", address))
 		}
 		addresses[address] = true
 	}
@@ -1500,7 +1500,7 @@ func ValidateNodeUpdate(node, oldNode *api.Node) validation.ErrorList {
 	// TODO: Add a 'real' error type for this error and provide print actual diffs.
 	if !api.Semantic.DeepEqual(oldNode, node) {
 		glog.V(4).Infof("Update failed validation %#v vs %#v", oldNode, node)
-		allErrs = append(allErrs, fmt.Errorf("update contains more than labels or capacity changes"))
+		allErrs = append(allErrs, validation.NewFieldForbidden("", "update contains more than labels or capacity changes"))
 	}
 
 	return allErrs

pkg/api/validation/validation_test.go

@@ -28,7 +28,6 @@ import (
 	"k8s.io/kubernetes/pkg/api/testapi"
 	"k8s.io/kubernetes/pkg/api/unversioned"
 	"k8s.io/kubernetes/pkg/capabilities"
-	utilerrors "k8s.io/kubernetes/pkg/util/errors"
 	"k8s.io/kubernetes/pkg/util/intstr"
 	"k8s.io/kubernetes/pkg/util/sets"
 	"k8s.io/kubernetes/pkg/util/validation"
@@ -36,7 +35,7 @@ import (
 
 func expectPrefix(t *testing.T, prefix string, errs validation.ErrorList) {
 	for i := range errs {
-		if f, p := errs[i].(*validation.Error).Field, prefix; !strings.HasPrefix(f, p) {
+		if f, p := errs[i].Field, prefix; !strings.HasPrefix(f, p) {
 			t.Errorf("expected prefix '%s' for field '%s' (%v)", p, f, errs[i])
 		}
 	}
@@ -150,7 +149,7 @@ func TestValidateLabels(t *testing.T) {
 		if len(errs) != 1 {
 			t.Errorf("case[%d] expected failure", i)
 		} else {
-			detail := errs[0].(*validation.Error).Detail
+			detail := errs[0].Detail
 			if detail != qualifiedNameErrorMsg {
 				t.Errorf("error detail %s should be equal %s", detail, qualifiedNameErrorMsg)
 			}
@@ -168,7 +167,7 @@ func TestValidateLabels(t *testing.T) {
 		if len(errs) != 1 {
 			t.Errorf("case[%d] expected failure", i)
 		} else {
-			detail := errs[0].(*validation.Error).Detail
+			detail := errs[0].Detail
 			if detail != labelValueErrorMsg {
 				t.Errorf("error detail %s should be equal %s", detail, labelValueErrorMsg)
 			}
@@ -215,7 +214,7 @@ func TestValidateAnnotations(t *testing.T) {
 		if len(errs) != 1 {
 			t.Errorf("case[%d] expected failure", i)
 		}
-		detail := errs[0].(*validation.Error).Detail
+		detail := errs[0].Detail
 		if detail != qualifiedNameErrorMsg {
 			t.Errorf("error detail %s should be equal %s", detail, qualifiedNameErrorMsg)
 		}
@@ -568,13 +567,13 @@ func TestValidateVolumes(t *testing.T) {
 			continue
 		}
 		for i := range errs {
-			if errs[i].(*validation.Error).Type != v.T {
+			if errs[i].Type != v.T {
 				t.Errorf("%s: expected errors to have type %s: %v", k, v.T, errs[i])
 			}
-			if errs[i].(*validation.Error).Field != v.F {
+			if errs[i].Field != v.F {
 				t.Errorf("%s: expected errors to have field %s: %v", k, v.F, errs[i])
 			}
-			detail := errs[i].(*validation.Error).Detail
+			detail := errs[i].Detail
 			if detail != v.D {
 				t.Errorf("%s: expected error detail \"%s\", got \"%s\"", k, v.D, detail)
 			}
@@ -627,13 +626,13 @@ func TestValidatePorts(t *testing.T) {
 			t.Errorf("expected failure for %s", k)
 		}
 		for i := range errs {
-			if errs[i].(*validation.Error).Type != v.T {
+			if errs[i].Type != v.T {
 				t.Errorf("%s: expected errors to have type %s: %v", k, v.T, errs[i])
 			}
-			if errs[i].(*validation.Error).Field != v.F {
+			if errs[i].Field != v.F {
 				t.Errorf("%s: expected errors to have field %s: %v", k, v.F, errs[i])
 			}
-			detail := errs[i].(*validation.Error).Detail
+			detail := errs[i].Detail
 			if detail != v.D {
 				t.Errorf("%s: expected error detail either empty or %s, got %s", k, v.D, detail)
 			}
@@ -772,7 +771,7 @@ func TestValidateEnv(t *testing.T) {
 			t.Errorf("expected failure for %s", tc.name)
 		} else {
 			for i := range errs {
-				str := errs[i].(*validation.Error).Error()
+				str := errs[i].Error()
 				if str != "" && str != tc.expectedError {
 					t.Errorf("%s: expected error detail either empty or %s, got %s", tc.name, tc.expectedError, str)
 				}
@@ -2108,7 +2107,7 @@ func TestValidateService(t *testing.T) {
 		tc.tweakSvc(&svc)
 		errs := ValidateService(&svc)
 		if len(errs) != tc.numErrs {
-			t.Errorf("Unexpected error list for case %q: %v", tc.name, utilerrors.NewAggregate(errs))
+			t.Errorf("Unexpected error list for case %q: %v", tc.name, errs.ToAggregate())
 		}
 	}
 }
@@ -2560,7 +2559,7 @@ func TestValidateReplicationController(t *testing.T) {
 			t.Errorf("expected failure for %s", k)
 		}
 		for i := range errs {
-			field := errs[i].(*validation.Error).Field
+			field := errs[i].Field
 			if !strings.HasPrefix(field, "spec.template.") &&
 				field != "metadata.name" &&
 				field != "metadata.namespace" &&
@@ -2676,7 +2675,7 @@ func TestValidateNode(t *testing.T) {
 			t.Errorf("expected failure for %s", k)
 		}
 		for i := range errs {
-			field := errs[i].(*validation.Error).Field
+			field := errs[i].Field
 			expectedFields := map[string]bool{
 				"metadata.name":        true,
 				"metadata.labels":      true,
@@ -2974,7 +2973,7 @@ func TestValidateServiceUpdate(t *testing.T) {
 		tc.tweakSvc(&oldSvc, &newSvc)
 		errs := ValidateServiceUpdate(&newSvc, &oldSvc)
 		if len(errs) != tc.numErrs {
-			t.Errorf("Unexpected error list for case %q: %v", tc.name, utilerrors.NewAggregate(errs))
+			t.Errorf("Unexpected error list for case %q: %v", tc.name, errs.ToAggregate())
 		}
 	}
 }
@@ -3008,7 +3007,7 @@ func TestValidateResourceNames(t *testing.T) {
 		} else if len(err) == 0 && !item.success {
 			t.Errorf("expected failure for input %q", item.input)
 			for i := range err {
-				detail := err[i].(*validation.Error).Detail
+				detail := err[i].Detail
 				if detail != "" && detail != qualifiedNameErrorMsg {
 					t.Errorf("%d: expected error detail either empty or %s, got %s", k, qualifiedNameErrorMsg, detail)
 				}
@@ -3224,7 +3223,7 @@ func TestValidateLimitRange(t *testing.T) {
 			t.Errorf("expected failure for %s", k)
 		}
 		for i := range errs {
-			detail := errs[i].(*validation.Error).Detail
+			detail := errs[i].Detail
 			if detail != v.D {
 				t.Errorf("%s: expected error detail either empty or %s, got %s", k, v.D, detail)
 			}
@@ -3329,8 +3328,8 @@ func TestValidateResourceQuota(t *testing.T) {
 			t.Errorf("expected failure for %s", k)
 		}
 		for i := range errs {
-			field := errs[i].(*validation.Error).Field
-			detail := errs[i].(*validation.Error).Detail
+			field := errs[i].Field
+			detail := errs[i].Detail
 			if field != "metadata.name" && field != "metadata.namespace" && !api.IsStandardResourceName(field) {
 				t.Errorf("%s: missing prefix for: %v", k, field)
 			}
@@ -3937,7 +3936,7 @@ func TestValidateEndpoints(t *testing.T) {
 	}
 
 	for k, v := range errorCases {
-		if errs := ValidateEndpoints(&v.endpoints); len(errs) == 0 || errs[0].(*validation.Error).Type != v.errorType || !strings.Contains(errs[0].(*validation.Error).Detail, v.errorDetail) {
+		if errs := ValidateEndpoints(&v.endpoints); len(errs) == 0 || errs[0].Type != v.errorType || !strings.Contains(errs[0].Detail, v.errorDetail) {
 			t.Errorf("Expected error type %s with detail %s for %s, got %v", v.errorType, v.errorDetail, k, errs)
 		}
 	}
@@ -4017,7 +4016,7 @@ func TestValidateSecurityContext(t *testing.T) {
 		},
 	}
 	for k, v := range errorCases {
-		if errs := ValidateSecurityContext(v.sc); len(errs) == 0 || errs[0].(*validation.Error).Type != v.errorType || errs[0].(*validation.Error).Detail != v.errorDetail {
+		if errs := ValidateSecurityContext(v.sc); len(errs) == 0 || errs[0].Type != v.errorType || errs[0].Detail != v.errorDetail {
 			t.Errorf("Expected error type %s with detail %s for %s, got %v", v.errorType, v.errorDetail, k, errs)
 		}
 	}

pkg/apis/extensions/validation/validation_test.go

@@ -24,7 +24,6 @@ import (
 	"k8s.io/kubernetes/pkg/api"
 	"k8s.io/kubernetes/pkg/apis/extensions"
 	"k8s.io/kubernetes/pkg/util/intstr"
-	"k8s.io/kubernetes/pkg/util/validation"
 )
 
 func TestValidateHorizontalPodAutoscaler(t *testing.T) {
@@ -675,7 +674,7 @@ func TestValidateDaemonSet(t *testing.T) {
 			t.Errorf("expected failure for %s", k)
 		}
 		for i := range errs {
-			field := errs[i].(*validation.Error).Field
+			field := errs[i].Field
 			if !strings.HasPrefix(field, "spec.template.") &&
 				field != "metadata.name" &&
 				field != "metadata.namespace" &&
@@ -918,9 +917,9 @@ func TestValidateJob(t *testing.T) {
 			t.Errorf("expected failure for %s", k)
 		} else {
 			s := strings.Split(k, ":")
-			err := errs[0].(*validation.Error)
+			err := errs[0]
 			if err.Field != s[0] || !strings.Contains(err.Error(), s[1]) {
-				t.Errorf("unexpected error: %v, expected: %s", errs[0], k)
+				t.Errorf("unexpected error: %v, expected: %s", err, k)
 			}
 		}
 	}
@@ -1019,9 +1018,9 @@ func TestValidateIngress(t *testing.T) {
 			t.Errorf("expected failure for %s", k)
 		} else {
 			s := strings.Split(k, ":")
-			err := errs[0].(*validation.Error)
+			err := errs[0]
 			if err.Field != s[0] || !strings.Contains(err.Error(), s[1]) {
-				t.Errorf("unexpected error: %v, expected: %s", errs[0], k)
+				t.Errorf("unexpected error: %v, expected: %s", err, k)
 			}
 		}
 	}
@@ -1111,9 +1110,9 @@ func TestValidateIngressStatusUpdate(t *testing.T) {
 			t.Errorf("expected failure for %s", k)
 		} else {
 			s := strings.Split(k, ":")
-			err := errs[0].(*validation.Error)
+			err := errs[0]
 			if err.Field != s[0] || !strings.Contains(err.Error(), s[1]) {
-				t.Errorf("unexpected error: %v, expected: %s", errs[0], k)
+				t.Errorf("unexpected error: %v, expected: %s", err, k)
 			}
 		}
 	}

pkg/kubectl/cmd/log.go

@@ -32,7 +32,6 @@ import (
 	cmdutil "k8s.io/kubernetes/pkg/kubectl/cmd/util"
 	"k8s.io/kubernetes/pkg/kubectl/resource"
 	"k8s.io/kubernetes/pkg/runtime"
-	kerrors "k8s.io/kubernetes/pkg/util/errors"
 )
 
 const (
@@ -169,7 +168,7 @@ func (o LogsOptions) Validate() error {
 		return errors.New("unexpected log options object")
 	}
 	if errs := validation.ValidatePodLogOptions(logOptions); len(errs) > 0 {
-		return kerrors.NewAggregate(errs)
+		return errs.ToAggregate()
 	}
 
 	return nil

pkg/kubelet/config/config.go

@@ -29,7 +29,6 @@ import (
 	kubetypes "k8s.io/kubernetes/pkg/kubelet/types"
 	kubeletutil "k8s.io/kubernetes/pkg/kubelet/util"
 	"k8s.io/kubernetes/pkg/util/config"
-	utilerrors "k8s.io/kubernetes/pkg/util/errors"
 	"k8s.io/kubernetes/pkg/util/sets"
 	utilvalidation "k8s.io/kubernetes/pkg/util/validation"
 )
@@ -310,7 +309,7 @@ func (s *podStorage) seenSources(sources ...string) bool {
 func filterInvalidPods(pods []*api.Pod, source string, recorder record.EventRecorder) (filtered []*api.Pod) {
 	names := sets.String{}
 	for i, pod := range pods {
-		var errlist []error
+		var errlist utilvalidation.ErrorList
 		if errs := validation.ValidatePod(pod); len(errs) != 0 {
 			errlist = append(errlist, errs...)
 			// If validation fails, don't trust it any further -
@@ -325,7 +324,7 @@ func filterInvalidPods(pods []*api.Pod, source string, recorder record.EventReco
 		}
 		if len(errlist) > 0 {
 			name := bestPodIdentString(pod)
-			err := utilerrors.NewAggregate(errlist)
+			err := errlist.ToAggregate()
 			glog.Warningf("Pod[%d] (%s) from %s failed validation, ignoring: %v", i+1, name, source, err)
 			recorder.Eventf(pod, kubecontainer.FailedValidation, "Error validating pod %s from %s, ignoring: %v", name, source, err)
 			continue

pkg/kubelet/config/http_test.go

@@ -30,7 +30,6 @@ import (
 	kubetypes "k8s.io/kubernetes/pkg/kubelet/types"
 	"k8s.io/kubernetes/pkg/runtime"
 	"k8s.io/kubernetes/pkg/util"
-	utilerrors "k8s.io/kubernetes/pkg/util/errors"
 )
 
 func TestURLErrorNotExistNoUpdate(t *testing.T) {
@@ -286,7 +285,7 @@ func TestExtractPodsFromHTTP(t *testing.T) {
 		}
 		for _, pod := range update.Pods {
 			if errs := validation.ValidatePod(pod); len(errs) != 0 {
-				t.Errorf("%s: Expected no validation errors on %#v, Got %v", testCase.desc, pod, utilerrors.NewAggregate(errs))
+				t.Errorf("%s: Expected no validation errors on %#v, Got %v", testCase.desc, pod, errs.ToAggregate())
 			}
 		}
 	}

pkg/util/validation/errors.go

@@ -46,7 +46,7 @@ func (v *Error) Error() string {
 func (v *Error) ErrorBody() string {
 	var s string
 	switch v.Type {
-	case ErrorTypeRequired, ErrorTypeTooLong:
+	case ErrorTypeRequired, ErrorTypeTooLong, ErrorTypeInternal:
 		s = spew.Sprintf("%s", v.Type)
 	default:
 		s = spew.Sprintf("%s '%+v'", v.Type, v.BadValue)
@@ -89,6 +89,9 @@ const (
 	// This is similar to ErrorTypeInvalid, but the error will not include the
 	// too-long value.  See NewFieldTooLong.
 	ErrorTypeTooLong ErrorType = "FieldValueTooLong"
+	// ErrorTypeInternal is used to report other errors that are not related
+	// to user input.
+	ErrorTypeInternal ErrorType = "InternalError"
 )
 
 // String converts a ErrorType into its corresponding canonical error message.
@@ -108,6 +111,8 @@ func (t ErrorType) String() string {
 		return "forbidden"
 	case ErrorTypeTooLong:
 		return "too long"
+	case ErrorTypeInternal:
+		return "internal error"
 	default:
 		panic(fmt.Sprintf("unrecognized validation error: %q", t))
 		return ""
@@ -166,24 +171,27 @@ func NewFieldTooLong(field string, value interface{}, maxLength int) *Error {
 	return &Error{ErrorTypeTooLong, field, value, fmt.Sprintf("must have at most %d characters", maxLength)}
 }
 
+// NewInternalError returns a *Error indicating "internal error".  This is used
+// to signal that an error was found that was not directly related to user
+// input.  The err argument must be non-nil.
+func NewInternalError(field string, err error) *Error {
+	return &Error{ErrorTypeInternal, field, nil, err.Error()}
+}
+
 // ErrorList holds a set of errors.
-type ErrorList []error
+type ErrorList []*Error
 
 // Prefix adds a prefix to the Field of every Error in the list.
 // Returns the list for convenience.
 func (list ErrorList) Prefix(prefix string) ErrorList {
 	for i := range list {
-		if err, ok := list[i].(*Error); ok {
-			if strings.HasPrefix(err.Field, "[") {
-				err.Field = prefix + err.Field
-			} else if len(err.Field) != 0 {
-				err.Field = prefix + "." + err.Field
-			} else {
-				err.Field = prefix
-			}
-			list[i] = err
+		err := list[i]
+		if strings.HasPrefix(err.Field, "[") {
+			err.Field = prefix + err.Field
+		} else if len(err.Field) != 0 {
+			err.Field = prefix + "." + err.Field
 		} else {
-			panic(fmt.Sprintf("Programmer error: ErrorList holds non-Error: %#v", list[i]))
+			err.Field = prefix
 		}
 	}
 	return list
@@ -206,13 +214,30 @@ func NewErrorTypeMatcher(t ErrorType) utilerrors.Matcher {
 	}
 }
 
+// ToAggregate converts the ErrorList into an errors.Aggregate.
+func (list ErrorList) ToAggregate() utilerrors.Aggregate {
+	errs := make([]error, len(list))
+	for i := range list {
+		errs[i] = list[i]
+	}
+	return utilerrors.NewAggregate(errs)
+}
+
+func fromAggregate(agg utilerrors.Aggregate) ErrorList {
+	errs := agg.Errors()
+	list := make(ErrorList, len(errs))
+	for i := range errs {
+		list[i] = errs[i].(*Error)
+	}
+	return list
+}
+
 // Filter removes items from the ErrorList that match the provided fns.
 func (list ErrorList) Filter(fns ...utilerrors.Matcher) ErrorList {
-	err := utilerrors.FilterOut(utilerrors.NewAggregate(list), fns...)
+	err := utilerrors.FilterOut(list.ToAggregate(), fns...)
 	if err == nil {
 		return nil
 	}
-	// FilterOut that takes an Aggregate returns an Aggregate
-	agg := err.(utilerrors.Aggregate)
-	return ErrorList(agg.Errors())
+	// FilterOut takes an Aggregate and returns an Aggregate
+	return fromAggregate(err.(utilerrors.Aggregate))
 }

pkg/util/validation/errors_test.go

@@ -17,6 +17,7 @@ limitations under the License.
 package validation
 
 import (
+	"fmt"
 	"strings"
 	"testing"
 )
@@ -46,6 +47,10 @@ func TestMakeFuncs(t *testing.T) {
 			func() *Error { return NewFieldRequired("f") },
 			ErrorTypeRequired,
 		},
+		{
+			func() *Error { return NewInternalError("f", fmt.Errorf("e")) },
+			ErrorTypeInternal,
+		},
 	}
 
 	for _, testCase := range testCases {
@@ -93,6 +98,27 @@ func TestErrorUsefulMessage(t *testing.T) {
 	}
 }
 
+func TestToAggregate(t *testing.T) {
+	testCases := []ErrorList{
+		nil,
+		{},
+		{NewFieldInvalid("f", "v", "d")},
+		{NewFieldInvalid("f", "v", "d"), NewInternalError("", fmt.Errorf("e"))},
+	}
+	for i, tc := range testCases {
+		agg := tc.ToAggregate()
+		if len(tc) == 0 {
+			if agg != nil {
+				t.Errorf("[%d] Expected nil, got %#v", i, agg)
+			}
+		} else if agg == nil {
+			t.Errorf("[%d] Expected non-nil", i)
+		} else if len(tc) != len(agg.Errors()) {
+			t.Errorf("[%d] Expected %d, got %d", i, len(tc), len(agg.Errors()))
+		}
+	}
+}
+
 func TestErrListFilter(t *testing.T) {
 	list := ErrorList{
 		NewFieldInvalid("test.field", "", ""),
@@ -131,7 +157,7 @@ func TestErrListPrefix(t *testing.T) {
 		if prefix == nil || len(prefix) != len(errList) {
 			t.Errorf("Prefix should return self")
 		}
-		if e, a := testCase.Expected, errList[0].(*Error).Field; e != a {
+		if e, a := testCase.Expected, errList[0].Field; e != a {
 			t.Errorf("expected %s, got %s", e, a)
 		}
 	}
@@ -161,7 +187,7 @@ func TestErrListPrefixIndex(t *testing.T) {
 		if prefix == nil || len(prefix) != len(errList) {
 			t.Errorf("PrefixIndex should return self")
 		}
-		if e, a := testCase.Expected, errList[0].(*Error).Field; e != a {
+		if e, a := testCase.Expected, errList[0].Field; e != a {
 			t.Errorf("expected %s, got %s", e, a)
 		}
 	}