Use a single deep copied object between all reactors in fake client

staging/src/k8s.io/client-go/testing/BUILD

@@ -34,7 +34,10 @@ go_library(
 
 go_test(
     name = "go_default_test",
-    srcs = ["fixture_test.go"],
+    srcs = [
+        "fake_test.go",
+        "fixture_test.go",
+    ],
     embed = [":go_default_library"],
     deps = [
         "//staging/src/k8s.io/apimachinery/pkg/api/meta:go_default_library",

staging/src/k8s.io/client-go/testing/fake.go

@@ -131,13 +131,14 @@ func (c *Fake) Invokes(action Action, defaultReturnObj runtime.Object) (runtime.
 	c.Lock()
 	defer c.Unlock()
 
+	actionCopy := action.DeepCopy()
 	c.actions = append(c.actions, action.DeepCopy())
 	for _, reactor := range c.ReactionChain {
-		if !reactor.Handles(action) {
+		if !reactor.Handles(actionCopy) {
 			continue
 		}
 
-		handled, ret, err := reactor.React(action.DeepCopy())
+		handled, ret, err := reactor.React(actionCopy)
 		if !handled {
 			continue
 		}
@@ -154,13 +155,14 @@ func (c *Fake) InvokesWatch(action Action) (watch.Interface, error) {
 	c.Lock()
 	defer c.Unlock()
 
+	actionCopy := action.DeepCopy()
 	c.actions = append(c.actions, action.DeepCopy())
 	for _, reactor := range c.WatchReactionChain {
-		if !reactor.Handles(action) {
+		if !reactor.Handles(actionCopy) {
 			continue
 		}
 
-		handled, ret, err := reactor.React(action.DeepCopy())
+		handled, ret, err := reactor.React(actionCopy)
 		if !handled {
 			continue
 		}
@@ -177,13 +179,14 @@ func (c *Fake) InvokesProxy(action Action) restclient.ResponseWrapper {
 	c.Lock()
 	defer c.Unlock()
 
+	actionCopy := action.DeepCopy()
 	c.actions = append(c.actions, action.DeepCopy())
 	for _, reactor := range c.ProxyReactionChain {
-		if !reactor.Handles(action) {
+		if !reactor.Handles(actionCopy) {
 			continue
 		}
 
-		handled, ret, err := reactor.React(action.DeepCopy())
+		handled, ret, err := reactor.React(actionCopy)
 		if !handled || err != nil {
 			continue
 		}

staging/src/k8s.io/client-go/testing/fake_test.go

@@ -0,0 +1,166 @@
+/*
+Copyright 2019 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 testing
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"k8s.io/apimachinery/pkg/api/meta"
+	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/apimachinery/pkg/runtime/schema"
+)
+
+func TestOriginalObjectCaptured(t *testing.T) {
+	// this ReactionFunc sets the resources ClusterName
+	const testClusterName = "some-value"
+	reactors := []ReactionFunc{
+		func(action Action) (bool, runtime.Object, error) {
+			createAction := action.(CreateActionImpl)
+			accessor, err := meta.Accessor(createAction.Object)
+			if err != nil {
+				return false, nil, err
+			}
+
+			// set any field on the resource
+			accessor.SetClusterName(testClusterName)
+
+			return true, createAction.Object, nil
+		},
+	}
+
+	// create a new Fake with the test reactors
+	f := &Fake{}
+	for _, r := range reactors {
+		f.AddReactor("", "", r)
+	}
+
+	// construct a test resource
+	testResource := schema.GroupVersionResource{Group: "", Version: "test_version", Resource: "test_kind"}
+	testObj := getArbitraryResource(testResource, "test_name", "test_namespace")
+
+	// create a fake CreateAction
+	action := CreateActionImpl{
+		Object: testObj,
+	}
+
+	// execute the reaction chain
+	ret, err := f.Invokes(action, nil)
+	assert.NoError(t, err, "running Invokes failed")
+
+	// obtain a metadata accessor for the returned resource
+	accessor, err := meta.Accessor(ret)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	// validate that the returned resource was modified by the ReactionFunc
+	if accessor.GetClusterName() != testClusterName {
+		t.Errorf("expected resource returned by Invokes to be modified by the ReactionFunc")
+	}
+	// verify one action was performed
+	if len(f.actions) != 1 {
+		t.Errorf("expected 1 action to be executed")
+		t.FailNow()
+	}
+	// check to ensure the recorded action has not been modified by the chain
+	createAction := f.actions[0].(CreateActionImpl)
+	accessor, err = meta.Accessor(createAction.Object)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if accessor.GetClusterName() != "" {
+		t.Errorf("expected Action recorded to not be modified by ReactionFunc but it was")
+	}
+}
+
+func TestReactorChangesPersisted(t *testing.T) {
+	// this ReactionFunc sets the resources ClusterName
+	const testClusterName = "some-value"
+	reactors := []ReactionFunc{
+		func(action Action) (bool, runtime.Object, error) {
+			createAction := action.(CreateActionImpl)
+			accessor, err := meta.Accessor(createAction.Object)
+			if err != nil {
+				return false, nil, err
+			}
+
+			// set any field on the resource
+			accessor.SetClusterName(testClusterName)
+
+			return false, createAction.Object, nil
+		},
+		func(action Action) (bool, runtime.Object, error) {
+			createAction := action.(CreateActionImpl)
+			accessor, err := meta.Accessor(createAction.Object)
+			if err != nil {
+				return false, nil, err
+			}
+
+			// ensure the clusterName is set to testClusterName already
+			if accessor.GetClusterName() != testClusterName {
+				t.Errorf("expected resource passed to second reactor to be modified by first reactor")
+			}
+
+			return true, createAction.Object, nil
+		},
+	}
+
+	// create a new Fake with the test reactors
+	f := &Fake{}
+	for _, r := range reactors {
+		f.AddReactor("", "", r)
+	}
+
+	// construct a test resource
+	testResource := schema.GroupVersionResource{Group: "", Version: "test_version", Resource: "test_kind"}
+	testObj := getArbitraryResource(testResource, "test_name", "test_namespace")
+
+	// create a fake CreateAction
+	action := CreateActionImpl{
+		Object: testObj,
+	}
+
+	// execute the reaction chain
+	ret, err := f.Invokes(action, nil)
+	assert.NoError(t, err, "running Invokes failed")
+
+	// obtain a metadata accessor for the returned resource
+	accessor, err := meta.Accessor(ret)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	// validate that the returned resource was modified by the ReactionFunc
+	if accessor.GetClusterName() != testClusterName {
+		t.Errorf("expected resource returned by Invokes to be modified by the ReactionFunc")
+	}
+	// verify one action was performed
+	if len(f.actions) != 1 {
+		t.Errorf("expected 1 action to be executed")
+		t.FailNow()
+	}
+	// check to ensure the recorded action has not been modified by the chain
+	createAction := f.actions[0].(CreateActionImpl)
+	accessor, err = meta.Accessor(createAction.Object)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if accessor.GetClusterName() != "" {
+		t.Errorf("expected Action recorded to not be modified by ReactionFunc but it was")
+	}
+}