Add test for mutatefield

pkg/transformers/mutatefield.go

@@ -0,0 +1,74 @@
+/*
+Copyright 2018 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 transformers
+
+import (
+	"fmt"
+)
+
+type mutateFunc func(interface{}) (interface{}, error)
+
+func mutateField(
+	m map[string]interface{},
+	pathToField []string,
+	createIfNotPresent bool,
+	fns ...mutateFunc) error {
+	if len(pathToField) == 0 {
+		return nil
+	}
+
+	_, found := m[pathToField[0]]
+	if !found {
+		if !createIfNotPresent {
+			return nil
+		}
+		m[pathToField[0]] = map[string]interface{}{}
+	}
+
+	if len(pathToField) == 1 {
+		var err error
+		for _, fn := range fns {
+			m[pathToField[0]], err = fn(m[pathToField[0]])
+			if err != nil {
+				return err
+			}
+		}
+		return nil
+	}
+
+	v := m[pathToField[0]]
+	newPathToField := pathToField[1:]
+	switch typedV := v.(type) {
+	case map[string]interface{}:
+		return mutateField(typedV, newPathToField, createIfNotPresent, fns...)
+	case []interface{}:
+		for i := range typedV {
+			item := typedV[i]
+			typedItem, ok := item.(map[string]interface{})
+			if !ok {
+				return fmt.Errorf("%#v is expected to be %T", item, typedItem)
+			}
+			err := mutateField(typedItem, newPathToField, createIfNotPresent, fns...)
+			if err != nil {
+				return err
+			}
+		}
+		return nil
+	default:
+		return fmt.Errorf("%#v is not expected to be a primitive type", typedV)
+	}
+}