Implement runtime.Object <-> map[string]interface{} conversion

pkg/api/BUILD

@@ -93,6 +93,7 @@ go_test(
         "//vendor:k8s.io/apimachinery/pkg/api/testing",
         "//vendor:k8s.io/apimachinery/pkg/apis/meta/v1",
         "//vendor:k8s.io/apimachinery/pkg/conversion",
+        "//vendor:k8s.io/apimachinery/pkg/conversion/unstructured",
         "//vendor:k8s.io/apimachinery/pkg/runtime",
         "//vendor:k8s.io/apimachinery/pkg/runtime/schema",
         "//vendor:k8s.io/apimachinery/pkg/runtime/serializer/protobuf",

pkg/api/unstructured_test.go

@@ -28,6 +28,8 @@ import (
 	kapitesting "k8s.io/kubernetes/pkg/api/testing"
 	"k8s.io/kubernetes/pkg/api/v1"
 
+	"k8s.io/apimachinery/pkg/conversion/unstructured"
+	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/util/diff"
 	"k8s.io/apimachinery/pkg/util/json"
 
@@ -95,27 +97,23 @@ func doRoundTrip(t *testing.T, group testapi.TestGroup, kind string) {
 		return
 	}
 
-	// TODO; Enable the following part of test once to/from unstructured
-	// format conversions are implemented.
-	/*
-		newUnstr := make(map[string]interface{})
-		err = unstructured.NewConverter().ToUnstructured(item, &newUnstr)
-		if err != nil {
-			t.Errorf("ToUnstructured failed: %v", err)
-			return
-		}
+	newUnstr := make(map[string]interface{})
+	err = unstructured.NewConverter().ToUnstructured(item, &newUnstr)
+	if err != nil {
+		t.Errorf("ToUnstructured failed: %v", err)
+		return
+	}
 
-		newObj := reflect.New(reflect.TypeOf(item).Elem()).Interface().(runtime.Object)
-		err = unstructured.NewConverter().FromUnstructured(newUnstr, newObj)
-		if err != nil {
-			t.Errorf("FromUnstructured failed: %v", err)
-			return
-		}
+	newObj := reflect.New(reflect.TypeOf(item).Elem()).Interface().(runtime.Object)
+	err = unstructured.NewConverter().FromUnstructured(newUnstr, newObj)
+	if err != nil {
+		t.Errorf("FromUnstructured failed: %v", err)
+		return
+	}
 
-		if !apiequality.Semantic.DeepEqual(item, newObj) {
-			t.Errorf("Object changed, diff: %v", diff.ObjectReflectDiff(item, newObj))
-		}
-	*/
+	if !apiequality.Semantic.DeepEqual(item, newObj) {
+		t.Errorf("Object changed, diff: %v", diff.ObjectReflectDiff(item, newObj))
+	}
 }
 
 func TestRoundTrip(t *testing.T) {
@@ -135,11 +133,8 @@ func TestRoundTrip(t *testing.T) {
 	}
 }
 
-// TODO; Enable the following benchmark once to/from unstructured
-// format conversions are implemented.
-/*
 func BenchmarkToFromUnstructured(b *testing.B) {
-	items := benchmarkItems()
+	items := benchmarkItems(b)
 	size := len(items)
 	b.ResetTimer()
 	for i := 0; i < b.N; i++ {
@@ -154,7 +149,6 @@ func BenchmarkToFromUnstructured(b *testing.B) {
 	}
 	b.StopTimer()
 }
-*/
 
 func BenchmarkToFromUnstructuredViaJSON(b *testing.B) {
 	items := benchmarkItems(b)

staging/src/k8s.io/apimachinery/pkg/conversion/unstructured/converter.go

+/*
+Copyright 2017 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package unstructured
+
+import (
+	"bytes"
+	encodingjson "encoding/json"
+	"fmt"
+	"reflect"
+	"strings"
+	"sync"
+	"sync/atomic"
+
+	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/apimachinery/pkg/util/json"
+)
+
+type structField struct {
+	structType reflect.Type
+	field      int
+}
+
+type fieldInfo struct {
+	name      string
+	nameValue reflect.Value
+}
+
+type fieldsCacheMap map[structField]*fieldInfo
+
+type fieldsCache struct {
+	sync.Mutex
+	value atomic.Value
+}
+
+func newFieldsCache() *fieldsCache {
+	cache := &fieldsCache{}
+	cache.value.Store(make(fieldsCacheMap))
+	return cache
+}
+
+var (
+	marshalerType          = reflect.TypeOf(new(encodingjson.Marshaler)).Elem()
+	unmarshalerType        = reflect.TypeOf(new(encodingjson.Unmarshaler)).Elem()
+	mapStringInterfaceType = reflect.TypeOf(map[string]interface{}{})
+	fieldCache             = newFieldsCache()
+)
+
+// Converter knows how to convert betweek runtime.Object and
+// Unstructured in both ways.
+type Converter struct {
+}
+
+func NewConverter() *Converter {
+	return &Converter{}
+}
+
+func (c *Converter) FromUnstructured(u map[string]interface{}, obj runtime.Object) error {
+	return fromUnstructured(reflect.ValueOf(u), reflect.ValueOf(obj).Elem())
+}
+
+func fromUnstructured(sv, dv reflect.Value) error {
+	sv = unwrapInterface(sv)
+	if !sv.IsValid() {
+		dv.Set(reflect.Zero(dv.Type()))
+		return nil
+	}
+	st, dt := sv.Type(), dv.Type()
+
+	switch dt.Kind() {
+	case reflect.Map, reflect.Slice, reflect.Ptr, reflect.Struct, reflect.Interface:
+		// Those require non-trivial conversion.
+	default:
+		// This should handle all simple types.
+		if st.AssignableTo(dt) {
+			dv.Set(sv)
+			return nil
+		}
+		if st.ConvertibleTo(dt) {
+			dv.Set(sv.Convert(dt))
+			return nil
+		}
+	}
+
+	// Check if the object has a custom JSON marshaller/unmarshaller.
+	if reflect.PtrTo(dt).Implements(unmarshalerType) {
+		data, err := json.Marshal(sv.Interface())
+		if err != nil {
+			return fmt.Errorf("error encoding %s to json: %v", st.String(), err)
+		}
+		unmarshaler := dv.Addr().Interface().(encodingjson.Unmarshaler)
+		return unmarshaler.UnmarshalJSON(data)
+	}
+
+	switch dt.Kind() {
+	case reflect.Map:
+		return mapFromUnstructured(sv, dv)
+	case reflect.Slice:
+		return sliceFromUnstructured(sv, dv)
+	case reflect.Ptr:
+		return pointerFromUnstructured(sv, dv)
+	case reflect.Struct:
+		return structFromUnstructured(sv, dv)
+	case reflect.Interface:
+		return interfaceFromUnstructured(sv, dv)
+	default:
+		return fmt.Errorf("unrecognized type: %v", dt.Kind())
+	}
+}
+
+func fieldInfoFromField(structType reflect.Type, field int) *fieldInfo {
+	fieldCacheMap := fieldCache.value.Load().(fieldsCacheMap)
+	if info, ok := fieldCacheMap[structField{structType, field}]; ok {
+		return info
+	}
+
+	// Cache miss - we need to compute the field name.
+	info := &fieldInfo{}
+	typeField := structType.Field(field)
+	jsonTag := typeField.Tag.Get("json")
+	if len(jsonTag) == 0 {
+		// Make the first character lowercase.
+		if typeField.Name == "" {
+			info.name = typeField.Name
+		} else {
+			info.name = strings.ToLower(typeField.Name[:1]) + typeField.Name[1:]
+		}
+	} else {
+		info.name = strings.Split(jsonTag, ",")[0]
+	}
+	info.nameValue = reflect.ValueOf(info.name)
+
+	fieldCache.Lock()
+	defer fieldCache.Unlock()
+	fieldCacheMap = fieldCache.value.Load().(fieldsCacheMap)
+	newFieldCacheMap := make(fieldsCacheMap)
+	for k, v := range fieldCacheMap {
+		newFieldCacheMap[k] = v
+	}
+	newFieldCacheMap[structField{structType, field}] = info
+	fieldCache.value.Store(newFieldCacheMap)
+	return info
+}
+
+func unwrapInterface(v reflect.Value) reflect.Value {
+	for v.Kind() == reflect.Interface {
+		v = v.Elem()
+	}
+	return v
+}
+
+func mapFromUnstructured(sv, dv reflect.Value) error {
+	st, dt := sv.Type(), dv.Type()
+	if st.Kind() != reflect.Map {
+		return fmt.Errorf("cannot restore map from %v", st.Kind())
+	}
+
+	if !st.Key().AssignableTo(dt.Key()) && !st.Key().ConvertibleTo(dt.Key()) {
+		return fmt.Errorf("cannot copy map with non-assignable keys: %v %v", st.Key(), dt.Key())
+	}
+
+	if sv.IsNil() {
+		dv.Set(reflect.Zero(dt))
+		return nil
+	}
+	dv.Set(reflect.MakeMap(dt))
+	for _, key := range sv.MapKeys() {
+		value := reflect.New(dt.Elem()).Elem()
+		if val := unwrapInterface(sv.MapIndex(key)); val.IsValid() {
+			if err := fromUnstructured(val, value); err != nil {
+				return err
+			}
+		} else {
+			value.Set(reflect.Zero(dt.Elem()))
+		}
+		if st.Key().AssignableTo(dt.Key()) {
+			dv.SetMapIndex(key, value)
+		} else {
+			dv.SetMapIndex(key.Convert(dt.Key()), value)
+		}
+	}
+	return nil
+}
+
+func sliceFromUnstructured(sv, dv reflect.Value) error {
+	st, dt := sv.Type(), dv.Type()
+	if st.Kind() == reflect.String && dt.Elem().Kind() == reflect.Uint8 {
+		// We store original []byte representation as string.
+		// This conversion is allowed, but we need to be careful about
+		// marshaling data appropriately.
+		if len(sv.Interface().(string)) > 0 {
+			marshalled, err := json.Marshal(sv.Interface())
+			if err != nil {
+				return fmt.Errorf("error encoding %s to json: %v", st, err)
+			}
+			// TODO: Is this Unmarshal needed?
+			var data []byte
+			err = json.Unmarshal(marshalled, &data)
+			if err != nil {
+				return fmt.Errorf("error decoding from json: %v", err)
+			}
+			dv.SetBytes(data)
+		} else {
+			dv.Set(reflect.Zero(dt))
+		}
+		return nil
+	}
+	if st.Kind() != reflect.Slice {
+		return fmt.Errorf("cannot restore slice from %v", st.Kind())
+	}
+
+	if sv.IsNil() {
+		dv.Set(reflect.Zero(dt))
+		return nil
+	}
+	dv.Set(reflect.MakeSlice(dt, sv.Len(), sv.Cap()))
+	for i := 0; i < sv.Len(); i++ {
+		if err := fromUnstructured(sv.Index(i), dv.Index(i)); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func pointerFromUnstructured(sv, dv reflect.Value) error {
+	st, dt := sv.Type(), dv.Type()
+
+	if st.Kind() == reflect.Ptr && sv.IsNil() {
+		dv.Set(reflect.Zero(dt))
+		return nil
+	}
+	dv.Set(reflect.New(dt.Elem()))
+	switch st.Kind() {
+	case reflect.Ptr, reflect.Interface:
+		return fromUnstructured(sv.Elem(), dv.Elem())
+	default:
+		return fromUnstructured(sv, dv.Elem())
+	}
+}
+
+func structFromUnstructured(sv, dv reflect.Value) error {
+	st, dt := sv.Type(), dv.Type()
+	if st.Kind() != reflect.Map {
+		return fmt.Errorf("cannot restore struct from: %v", st.Kind())
+	}
+
+	for i := 0; i < dt.NumField(); i++ {
+		fieldInfo := fieldInfoFromField(dt, i)
+		fv := dv.Field(i)
+
+		if len(fieldInfo.name) == 0 {
+			// This field is inlined.
+			if err := fromUnstructured(sv, fv); err != nil {
+				return err
+			}
+		} else {
+			value := unwrapInterface(sv.MapIndex(fieldInfo.nameValue))
+			if value.IsValid() {
+				if err := fromUnstructured(value, fv); err != nil {
+					return err
+				}
+			} else {
+				fv.Set(reflect.Zero(fv.Type()))
+			}
+		}
+	}
+	return nil
+}
+
+func interfaceFromUnstructured(sv, dv reflect.Value) error {
+	// TODO: Is this conversion safe?
+	dv.Set(sv)
+	return nil
+}
+
+func (c *Converter) ToUnstructured(obj runtime.Object, u *map[string]interface{}) error {
+	return toUnstructured(reflect.ValueOf(obj).Elem(), reflect.ValueOf(u).Elem())
+}
+
+func toUnstructured(sv, dv reflect.Value) error {
+	st, dt := sv.Type(), dv.Type()
+
+	// Check if the object has a custom JSON marshaller/unmarshaller.
+	if st.Implements(marshalerType) {
+		if sv.Kind() == reflect.Ptr && sv.IsNil() {
+			// We're done - we don't need to store anything.
+			return nil
+		}
+
+		marshaler := sv.Interface().(encodingjson.Marshaler)
+		data, err := marshaler.MarshalJSON()
+		if err != nil {
+			return err
+		}
+		if bytes.Equal(data, []byte("null")) {
+			// We're done - we don't need to store anything.
+		} else {
+			switch {
+			case len(data) > 0 && data[0] == '"':
+				var result string
+				err := json.Unmarshal(data, &result)
+				if err != nil {
+					return fmt.Errorf("error decoding from json: %v", err)
+				}
+				dv.Set(reflect.ValueOf(result))
+			case len(data) > 0 && data[0] == '{':
+				result := make(map[string]interface{})
+				err := json.Unmarshal(data, &result)
+				if err != nil {
+					return fmt.Errorf("error decoding from json: %v", err)
+				}
+				dv.Set(reflect.ValueOf(result))
+			default:
+				var result int64
+				err := json.Unmarshal(data, &result)
+				if err != nil {
+					return fmt.Errorf("error decoding from json: %v", err)
+				}
+				dv.Set(reflect.ValueOf(result))
+			}
+		}
+		return nil
+	}
+
+	switch st.Kind() {
+	case reflect.String, reflect.Bool,
+		reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
+		reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64,
+		reflect.Float32, reflect.Float64:
+		if dt.Kind() == reflect.Interface && dv.NumMethod() == 0 {
+			dv.Set(reflect.New(st))
+		}
+		dv.Set(sv)
+		return nil
+	case reflect.Map:
+		return mapToUnstructured(sv, dv)
+	case reflect.Slice:
+		return sliceToUnstructured(sv, dv)
+	case reflect.Ptr:
+		return pointerToUnstructured(sv, dv)
+	case reflect.Struct:
+		return structToUnstructured(sv, dv)
+	case reflect.Interface:
+		return interfaceToUnstructured(sv, dv)
+	default:
+		return fmt.Errorf("unrecognized type: %v", st.Kind())
+	}
+}
+
+func mapToUnstructured(sv, dv reflect.Value) error {
+	st, dt := sv.Type(), dv.Type()
+	if sv.IsNil() {
+		dv.Set(reflect.Zero(dt))
+		return nil
+	}
+	if dt.Kind() == reflect.Interface && dv.NumMethod() == 0 {
+		if st.Key().Kind() == reflect.String {
+			switch st.Elem().Kind() {
+			// TODO It should be possible to reuse the slice for primitive types.
+			// However, it is panicing in the following form.
+			// case reflect.String, reflect.Bool,
+			// 	reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
+			// 	reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+			// 	sv.Set(sv)
+			// 	return nil
+			default:
+				// We need to do a proper conversion.
+			}
+		}
+		dv.Set(reflect.MakeMap(mapStringInterfaceType))
+		dv = dv.Elem()
+		dt = dv.Type()
+	}
+	if dt.Kind() != reflect.Map {
+		return fmt.Errorf("cannot convert struct to: %v", dt.Kind())
+	}
+
+	if !st.Key().AssignableTo(dt.Key()) && !st.Key().ConvertibleTo(dt.Key()) {
+		return fmt.Errorf("cannot copy map with non-assignable keys: %v %v", st.Key(), dt.Key())
+	}
+
+	for _, key := range sv.MapKeys() {
+		value := reflect.New(dt.Elem()).Elem()
+		if err := toUnstructured(sv.MapIndex(key), value); err != nil {
+			return err
+		}
+		if st.Key().AssignableTo(dt.Key()) {
+			dv.SetMapIndex(key, value)
+		} else {
+			dv.SetMapIndex(key.Convert(dt.Key()), value)
+		}
+	}
+	return nil
+}
+
+func sliceToUnstructured(sv, dv reflect.Value) error {
+	st, dt := sv.Type(), dv.Type()
+	if sv.IsNil() {
+		dv.Set(reflect.Zero(dt))
+		return nil
+	}
+	if dt.Kind() == reflect.Interface && dv.NumMethod() == 0 {
+		switch st.Elem().Kind() {
+		// TODO It should be possible to reuse the slice for primitive types.
+		// However, it is panicing in the following form.
+		// case reflect.String, reflect.Bool,
+		// 	reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
+		// 	reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+		// 	sv.Set(sv)
+		// 	return nil
+		default:
+			// We need to do a proper conversion.
+			dv.Set(reflect.MakeSlice(reflect.SliceOf(dt), sv.Len(), sv.Cap()))
+			dv = dv.Elem()
+			dt = dv.Type()
+		}
+	}
+	if dt.Kind() != reflect.Slice {
+		return fmt.Errorf("cannot convert slice to: %v", dt.Kind())
+	}
+	for i := 0; i < sv.Len(); i++ {
+		if err := toUnstructured(sv.Index(i), dv.Index(i)); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func pointerToUnstructured(sv, dv reflect.Value) error {
+	if sv.IsNil() {
+		// We're done - we don't need to store anything.
+		return nil
+	}
+	return toUnstructured(sv.Elem(), dv)
+}
+
+func structToUnstructured(sv, dv reflect.Value) error {
+	st, dt := sv.Type(), dv.Type()
+	if dt.Kind() == reflect.Interface && dv.NumMethod() == 0 {
+		dv.Set(reflect.MakeMap(mapStringInterfaceType))
+		dv = dv.Elem()
+		dt = dv.Type()
+	}
+	if dt.Kind() != reflect.Map {
+		return fmt.Errorf("cannot convert struct to: %v", dt.Kind())
+	}
+
+	for i := 0; i < st.NumField(); i++ {
+		fieldInfo := fieldInfoFromField(st, i)
+		fv := sv.Field(i)
+
+		if len(fieldInfo.name) == 0 {
+			// This field is inlined.
+			if err := toUnstructured(fv, dv); err != nil {
+				return err
+			}
+			continue
+		}
+		if !fv.IsValid() {
+			// No fource field, skip.
+			continue
+		}
+		var subv reflect.Value
+		switch fv.Type().Kind() {
+		case reflect.String, reflect.Bool,
+			reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
+			reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+			subv = fv
+		default:
+			subv = reflect.New(dt.Elem()).Elem()
+			if err := toUnstructured(fv, subv); err != nil {
+				return err
+			}
+		}
+		// TODO: It seems this is causing 2 allocations per call, even if subv = fv.
+		dv.SetMapIndex(fieldInfo.nameValue, subv)
+	}
+	return nil
+}
+
+func interfaceToUnstructured(sv, dv reflect.Value) error {
+	if !sv.IsValid() || sv.IsNil() {
+		dv.Set(reflect.Zero(dv.Type()))
+		return nil
+	}
+	return toUnstructured(sv.Elem(), dv)
+}

staging/src/k8s.io/apimachinery/pkg/conversion/unstructured/converter_test.go

+/*
+Copyright 2015 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package unstructured
+
+import (
+	"reflect"
+	"testing"
+
+	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+	"k8s.io/apimachinery/pkg/util/diff"
+	"k8s.io/apimachinery/pkg/util/json"
+)
+
+// Definte a number of test types.
+type A struct {
+	A int `json:"aa,omitempty"`
+	B string `json:"ab,omitempty"`
+	C bool `json:"ac,omitempty"`
+}
+
+type B struct {
+	A A `json:"ba"`
+	B string `json:"bb"`
+	C map[string]string `json:"bc"`
+	D []string `json:"bd"`
+}
+
+type C struct {
+	A []A `json:"ca"`
+	B B `json:",inline"`
+	C string `json:"cc"`
+	D *int64 `json:"cd"`
+	E map[string]int `json:"ce"`
+	F []bool `json:"cf"`
+	G []int `json"cg"`
+	H float32 `json:ch"`
+	I []interface{} `json:"ci"`
+}
+
+// C needs to implement runtime.Object to make it usable for tests.
+func (c *C) GetObjectKind() schema.ObjectKind {
+	return schema.EmptyObjectKind
+}
+
+func doRoundTrip(t *testing.T, item runtime.Object) {
+	data, err := json.Marshal(item)
+	if err != nil {
+		t.Errorf("Error when marshaling object: %v", err)
+		return
+	}
+
+	unstr := make(map[string]interface{})
+	err = json.Unmarshal(data, &unstr)
+	if err != nil {
+		t.Errorf("Error when unmarshaling to unstructured: %v", err)
+		return
+	}
+
+	data, err = json.Marshal(unstr)
+	if err != nil {
+		t.Errorf("Error when marshaling unstructured: %v", err)
+		return
+	}
+	unmarshalledObj := reflect.New(reflect.TypeOf(item).Elem()).Interface()
+	err = json.Unmarshal(data, &unmarshalledObj)
+	if err != nil {
+		t.Errorf("Error when unmarshaling to object: %v", err)
+		return
+	}
+	if !reflect.DeepEqual(item, unmarshalledObj) {
+		t.Errorf("Object changed during JSON operations, diff: %v", diff.ObjectReflectDiff(item, unmarshalledObj))
+		return
+	}
+
+	newUnstr := make(map[string]interface{})
+	err = NewConverter().ToUnstructured(item, &newUnstr)
+	if err != nil {
+		t.Errorf("ToUnstructured failed: %v", err)
+		return
+	}
+
+	newObj := reflect.New(reflect.TypeOf(item).Elem()).Interface().(runtime.Object)
+	err = NewConverter().FromUnstructured(newUnstr, newObj)
+	if err != nil {
+		t.Errorf("FromUnstructured failed: %v", err)
+		return
+	}
+
+	if !reflect.DeepEqual(item, newObj) {
+		t.Errorf("Object changed, diff: %v", diff.ObjectReflectDiff(item, newObj))
+	}
+}
+
+func TestRoundTrip(t *testing.T) {
+	intVal := int64(42)
+	testCases := []struct{
+		obj runtime.Object
+	}{
+		{
+			// This (among others) tests nil map, slice and pointer.
+			obj: &C{
+				C: "ccc",
+			},
+		},
+		{
+			// This (among others) tests empty map and slice.
+			obj: &C{
+				A: []A{},
+				C: "ccc",
+				E: map[string]int{},
+				I: []interface{}{},
+			},
+		},
+		{
+			obj: &C{
+				A: []A{
+					{
+						A: 1,
+						B: "11",
+						C: true,
+					},
+					{
+						A: 2,
+						B: "22",
+						C: false,
+					},
+				},
+				B: B{
+					A: A{
+						A: 3,
+						B: "33",
+					},
+					B: "bbb",
+					C: map[string]string{
+						"k1": "v1",
+						"k2": "v2",
+					},
+					D: []string{"s1", "s2"},
+				},
+				C: "ccc",
+				D: &intVal,
+				E: map[string]int{
+					"k1": 1,
+					"k2": 2,
+				},
+				F: []bool{true, false, false},
+				G: []int{1, 2, 5},
+				H: 3.3,
+				I: []interface{}{nil, nil, nil},
+			},
+		},
+		{
+			// Test slice of interface{} with empty slices.
+			obj: &C{
+				I: []interface{}{[]interface{}{}, []interface{}{}},
+			},
+		},
+	}
+
+	for i := range testCases {
+		doRoundTrip(t, testCases[i].obj)
+		if t.Failed() {
+			break
+		}
+	}
+}

staging/src/k8s.io/apimachinery/pkg/conversion/unstructured/doc.go

+/*
+Copyright 2017 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+// Package unstructured provides conversion from runtime objects
+// to map[string]interface{} representation.
+package unstructured // import "k8s.io/apimachinery/pkg/conversion/unstructured"

vendor/BUILD

@@ -15414,3 +15414,29 @@ go_library(
         "//vendor:k8s.io/sample-apiserver/pkg/apis/wardle",
     ],
 )
+
+go_test(
+    name = "k8s.io/apimachinery/pkg/conversion/unstructured_test",
+    srcs = ["k8s.io/apimachinery/pkg/conversion/unstructured/converter_test.go"],
+    library = ":k8s.io/apimachinery/pkg/conversion/unstructured",
+    tags = ["automanaged"],
+    deps = [
+        "//vendor:k8s.io/apimachinery/pkg/runtime",
+        "//vendor:k8s.io/apimachinery/pkg/runtime/schema",
+        "//vendor:k8s.io/apimachinery/pkg/util/diff",
+        "//vendor:k8s.io/apimachinery/pkg/util/json",
+    ],
+)
+
+go_library(
+    name = "k8s.io/apimachinery/pkg/conversion/unstructured",
+    srcs = [
+        "k8s.io/apimachinery/pkg/conversion/unstructured/converter.go",
+        "k8s.io/apimachinery/pkg/conversion/unstructured/doc.go",
+    ],
+    tags = ["automanaged"],
+    deps = [
+        "//vendor:k8s.io/apimachinery/pkg/runtime",
+        "//vendor:k8s.io/apimachinery/pkg/util/json",
+    ],
+)