kubernetes/pkg/controller/persistentvolume/persistentvolume_framework_test.go

/*
Copyright 2016 The Kubernetes Authors All rights reserved.

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 persistentvolume

import (
	"errors"
	"fmt"
	"reflect"
	"strconv"
	"strings"
	"sync"
	"sync/atomic"
	"testing"
	"time"

	"github.com/golang/glog"

	"k8s.io/kubernetes/pkg/api"
	"k8s.io/kubernetes/pkg/api/resource"
	"k8s.io/kubernetes/pkg/api/testapi"
	"k8s.io/kubernetes/pkg/client/cache"
	clientset "k8s.io/kubernetes/pkg/client/clientset_generated/internalclientset"
	"k8s.io/kubernetes/pkg/client/clientset_generated/internalclientset/fake"
	"k8s.io/kubernetes/pkg/client/record"
	"k8s.io/kubernetes/pkg/client/testing/core"
	"k8s.io/kubernetes/pkg/controller/framework"
	"k8s.io/kubernetes/pkg/conversion"
	"k8s.io/kubernetes/pkg/runtime"
	"k8s.io/kubernetes/pkg/types"
	"k8s.io/kubernetes/pkg/util/diff"
	vol "k8s.io/kubernetes/pkg/volume"
)

// This is a unit test framework for persistent volume controller.
// It fills the controller with test claims/volumes and can simulate these
// scenarios:
// 1) Call syncClaim/syncVolume once.
// 2) Call syncClaim/syncVolume several times (both simulating "claim/volume
//    modified" events and periodic sync), until the controller settles down and
//    does not modify anything.
// 3) Simulate almost real API server/etcd and call add/update/delete
//    volume/claim.
// In all these scenarios, when the test finishes, the framework can compare
// resulting claims/volumes with list of expected claims/volumes and report
// differences.

// controllerTest contains a single controller test input.
// Each test has initial set of volumes and claims that are filled into the
// controller before the test starts. The test then contains a reference to
// function to call as the actual test. Available functions are:
//   - testSyncClaim - calls syncClaim on the first claim in initialClaims.
//   - testSyncClaimError - calls syncClaim on the first claim in initialClaims
//                          and expects an error to be returned.
//   - testSyncVolume - calls syncVolume on the first volume in initialVolumes.
//   - any custom function for specialized tests.
// The test then contains list of volumes/claims that are expected at the end
// of the test and list of generated events.
type controllerTest struct {
	// Name of the test, for logging
	name string
	// Initial content of controller volume cache.
	initialVolumes []*api.PersistentVolume
	// Expected content of controller volume cache at the end of the test.
	expectedVolumes []*api.PersistentVolume
	// Initial content of controller claim cache.
	initialClaims []*api.PersistentVolumeClaim
	// Expected content of controller claim cache at the end of the test.
	expectedClaims []*api.PersistentVolumeClaim
	// Expected events - any event with prefix will pass, we don't check full
	// event message.
	expectedEvents []string
	// Function to call as the test.
	test testCall
}

type testCall func(ctrl *PersistentVolumeController, reactor *volumeReactor, test controllerTest) error

const testNamespace = "default"

var versionConflictError = errors.New("VersionError")
var novolumes []*api.PersistentVolume
var noclaims []*api.PersistentVolumeClaim
var noevents = []string{}

// volumeReactor is a core.Reactor that simulates etcd and API server. It
// stores:
// - Latest version of claims volumes saved by the controller.
// - Queue of all saves (to simulate "volume/claim updated" events). This queue
//   contains all intermediate state of an object - e.g. a claim.VolumeName
//   is updated first and claim.Phase second. This queue will then contain both
//   updates as separate entries.
// - Number of changes since the last call to volumeReactor.syncAll().
// - Optionally, volume and claim event sources. When set, all changed
//   volumes/claims are sent as Modify event to these sources. These sources can
//   be linked back to the controller watcher as "volume/claim updated" events.
type volumeReactor struct {
	volumes              map[string]*api.PersistentVolume
	claims               map[string]*api.PersistentVolumeClaim
	changedObjects       []interface{}
	changedSinceLastSync int
	ctrl                 *PersistentVolumeController
	volumeSource         *framework.FakeControllerSource
	claimSource          *framework.FakeControllerSource
	lock                 sync.Mutex
}

// React is a callback called by fake kubeClient from the controller.
// In other words, every claim/volume change performed by the controller ends
// here.
// This callback checks versions of the updated objects and refuse those that
// are too old (simulating real etcd).
// All updated objects are stored locally to keep track of object versions and
// to evaluate test results.
// All updated objects are also inserted into changedObjects queue and
// optionally sent back to the controller via its watchers.
func (r *volumeReactor) React(action core.Action) (handled bool, ret runtime.Object, err error) {
	r.lock.Lock()
	defer r.lock.Unlock()

	glog.V(4).Infof("reactor got operation %q on %q", action.GetVerb(), action.GetResource())

	switch {
	case action.Matches("update", "persistentvolumes"):
		obj := action.(core.UpdateAction).GetObject()
		volume := obj.(*api.PersistentVolume)

		// Check and bump object version
		storedVolume, found := r.volumes[volume.Name]
		if found {
			storedVer, _ := strconv.Atoi(storedVolume.ResourceVersion)
			requestedVer, _ := strconv.Atoi(volume.ResourceVersion)
			if storedVer != requestedVer {
				return true, obj, versionConflictError
			}
			volume.ResourceVersion = strconv.Itoa(storedVer + 1)
		} else {
			return true, nil, fmt.Errorf("Cannot update volume %s: volume not found", volume.Name)
		}

		// Store the updated object to appropriate places.
		if r.volumeSource != nil {
			r.volumeSource.Modify(volume)
		}
		r.volumes[volume.Name] = volume
		r.changedObjects = append(r.changedObjects, volume)
		r.changedSinceLastSync++
		glog.V(4).Infof("saved updated volume %s", volume.Name)
		return true, volume, nil

	case action.Matches("update", "persistentvolumeclaims"):
		obj := action.(core.UpdateAction).GetObject()
		claim := obj.(*api.PersistentVolumeClaim)

		// Check and bump object version
		storedClaim, found := r.claims[claim.Name]
		if found {
			storedVer, _ := strconv.Atoi(storedClaim.ResourceVersion)
			requestedVer, _ := strconv.Atoi(claim.ResourceVersion)
			if storedVer != requestedVer {
				return true, obj, versionConflictError
			}
			claim.ResourceVersion = strconv.Itoa(storedVer + 1)
		} else {
			return true, nil, fmt.Errorf("Cannot update claim %s: claim not found", claim.Name)
		}

		// Store the updated object to appropriate places.
		r.claims[claim.Name] = claim
		if r.claimSource != nil {
			r.claimSource.Modify(claim)
		}
		r.changedObjects = append(r.changedObjects, claim)
		r.changedSinceLastSync++
		glog.V(4).Infof("saved updated claim %s", claim.Name)
		return true, claim, nil

	case action.Matches("get", "persistentvolumes"):
		name := action.(core.GetAction).GetName()
		volume, found := r.volumes[name]
		if found {
			glog.V(4).Infof("GetVolume: found %s", volume.Name)
			return true, volume, nil
		} else {
			glog.V(4).Infof("GetVolume: volume %s not found", name)
			return true, nil, fmt.Errorf("Cannot find volume %s", name)
		}

	case action.Matches("delete", "persistentvolumes"):
		name := action.(core.DeleteAction).GetName()
		glog.V(4).Infof("deleted volume %s", name)
		_, found := r.volumes[name]
		if found {
			delete(r.volumes, name)
			return true, nil, nil
		} else {
			return true, nil, fmt.Errorf("Cannot delete volume %s: not found", name)
		}

	case action.Matches("delete", "persistentvolumeclaims"):
		name := action.(core.DeleteAction).GetName()
		glog.V(4).Infof("deleted claim %s", name)
		_, found := r.volumes[name]
		if found {
			delete(r.claims, name)
			return true, nil, nil
		} else {
			return true, nil, fmt.Errorf("Cannot delete claim %s: not found", name)
		}
	}

	return false, nil, nil
}

// checkVolumes compares all expectedVolumes with set of volumes at the end of
// the test and reports differences.
func (r *volumeReactor) checkVolumes(t *testing.T, expectedVolumes []*api.PersistentVolume) error {
	r.lock.Lock()
	defer r.lock.Unlock()

	expectedMap := make(map[string]*api.PersistentVolume)
	gotMap := make(map[string]*api.PersistentVolume)
	// Clear any ResourceVersion from both sets
	for _, v := range expectedVolumes {
		v.ResourceVersion = ""
		expectedMap[v.Name] = v
	}
	for _, v := range r.volumes {
		// We must clone the volume because of golang race check - it was
		// written by the controller without any locks on it.
		clone, _ := conversion.NewCloner().DeepCopy(v)
		v = clone.(*api.PersistentVolume)
		v.ResourceVersion = ""
		if v.Spec.ClaimRef != nil {
			v.Spec.ClaimRef.ResourceVersion = ""
		}
		gotMap[v.Name] = v
	}
	if !reflect.DeepEqual(expectedMap, gotMap) {
		// Print ugly but useful diff of expected and received objects for
		// easier debugging.
		return fmt.Errorf("Volume check failed [A-expected, B-got]: %s", diff.ObjectDiff(expectedMap, gotMap))
	}
	return nil
}

// checkClaims compares all expectedClaims with set of claims at the end of the
// test and reports differences.
func (r *volumeReactor) checkClaims(t *testing.T, expectedClaims []*api.PersistentVolumeClaim) error {
	r.lock.Lock()
	defer r.lock.Unlock()

	expectedMap := make(map[string]*api.PersistentVolumeClaim)
	gotMap := make(map[string]*api.PersistentVolumeClaim)
	for _, c := range expectedClaims {
		c.ResourceVersion = ""
		expectedMap[c.Name] = c
	}
	for _, c := range r.claims {
		// We must clone the claim because of golang race check - it was
		// written by the controller without any locks on it.
		clone, _ := conversion.NewCloner().DeepCopy(c)
		c = clone.(*api.PersistentVolumeClaim)
		c.ResourceVersion = ""
		gotMap[c.Name] = c
	}
	if !reflect.DeepEqual(expectedMap, gotMap) {
		// Print ugly but useful diff of expected and received objects for
		// easier debugging.
		return fmt.Errorf("Claim check failed [A-expected, B-got result]: %s", diff.ObjectDiff(expectedMap, gotMap))
	}
	return nil
}

// checkEvents compares all expectedEvents with events generated during the test
// and reports differences.
func checkEvents(t *testing.T, expectedEvents []string, ctrl *PersistentVolumeController) error {
	var err error

	// Read recorded events
	fakeRecorder := ctrl.eventRecorder.(*record.FakeRecorder)
	gotEvents := []string{}
	finished := false
	for !finished {
		select {
		case event, ok := <-fakeRecorder.Events:
			if ok {
				glog.V(5).Infof("event recorder got event %s", event)
				gotEvents = append(gotEvents, event)
			} else {
				glog.V(5).Infof("event recorder finished")
				finished = true
			}
		default:
			glog.V(5).Infof("event recorder finished")
			finished = true
		}
	}

	// Evaluate the events
	for i, expected := range expectedEvents {
		if len(gotEvents) <= i {
			t.Errorf("Event %q not emitted", expected)
			err = fmt.Errorf("Events do not match")
			continue
		}
		received := gotEvents[i]
		if !strings.HasPrefix(received, expected) {
			t.Errorf("Unexpected event received, expected %q, got %q", expected, received)
			err = fmt.Errorf("Events do not match")
		}
	}
	for i := len(expectedEvents); i < len(gotEvents); i++ {
		t.Errorf("Unexpected event received: %q", gotEvents[i])
		err = fmt.Errorf("Events do not match")
	}
	return err
}

// popChange returns one recorded updated object, either *api.PersistentVolume
// or *api.PersistentVolumeClaim. Returns nil when there are no changes.
func (r *volumeReactor) popChange() interface{} {
	r.lock.Lock()
	defer r.lock.Unlock()

	if len(r.changedObjects) == 0 {
		return nil
	}

	// For debugging purposes, print the queue
	for _, obj := range r.changedObjects {
		switch obj.(type) {
		case *api.PersistentVolume:
			vol, _ := obj.(*api.PersistentVolume)
			glog.V(4).Infof("reactor queue: %s", vol.Name)
		case *api.PersistentVolumeClaim:
			claim, _ := obj.(*api.PersistentVolumeClaim)
			glog.V(4).Infof("reactor queue: %s", claim.Name)
		}
	}

	// Pop the first item from the queue and return it
	obj := r.changedObjects[0]
	r.changedObjects = r.changedObjects[1:]
	return obj
}

// syncAll simulates the controller periodic sync of volumes and claim. It
// simply adds all these objects to the internal queue of updates. This method
// should be used when the test manually calls syncClaim/syncVolume. Test that
// use real controller loop (ctrl.Run()) will get periodic sync automatically.
func (r *volumeReactor) syncAll() {
	r.lock.Lock()
	defer r.lock.Unlock()

	for _, c := range r.claims {
		r.changedObjects = append(r.changedObjects, c)
	}
	for _, v := range r.volumes {
		r.changedObjects = append(r.changedObjects, v)
	}
	r.changedSinceLastSync = 0
}

func (r *volumeReactor) getChangeCount() int {
	r.lock.Lock()
	defer r.lock.Unlock()
	return r.changedSinceLastSync
}

func (r *volumeReactor) getOperationCount() int {
	r.ctrl.runningOperationsMapLock.Lock()
	defer r.ctrl.runningOperationsMapLock.Unlock()
	return len(r.ctrl.runningOperations)
}

// waitTest waits until all tests, controllers and other goroutines do their
// job and no new actions are registered for 10 milliseconds.
func (r *volumeReactor) waitTest() {
	// Check every 10ms if the controller does something and stop if it's
	// idle.
	oldChanges := -1
	for {
		time.Sleep(10 * time.Millisecond)
		changes := r.getChangeCount()
		if changes == oldChanges && r.getOperationCount() == 0 {
			// No changes for last 10ms -> controller must be idle.
			break
		}
		oldChanges = changes
	}
}

func newVolumeReactor(client *fake.Clientset, ctrl *PersistentVolumeController, volumeSource, claimSource *framework.FakeControllerSource) *volumeReactor {
	reactor := &volumeReactor{
		volumes:      make(map[string]*api.PersistentVolume),
		claims:       make(map[string]*api.PersistentVolumeClaim),
		ctrl:         ctrl,
		volumeSource: volumeSource,
		claimSource:  claimSource,
	}
	client.AddReactor("*", "*", reactor.React)
	return reactor
}

func newPersistentVolumeController(kubeClient clientset.Interface) *PersistentVolumeController {
	ctrl := &PersistentVolumeController{
		volumes:           newPersistentVolumeOrderedIndex(),
		claims:            cache.NewStore(cache.MetaNamespaceKeyFunc),
		kubeClient:        kubeClient,
		eventRecorder:     record.NewFakeRecorder(1000),
		runningOperations: make(map[string]bool),
	}
	return ctrl
}

func addRecyclePlugin(ctrl *PersistentVolumeController, expectedRecycleCalls []error) {
	plugin := &mockVolumePlugin{
		recycleCalls: expectedRecycleCalls,
	}
	ctrl.recyclePluginMgr.InitPlugins([]vol.VolumePlugin{plugin}, ctrl)
}

func addDeletePlugin(ctrl *PersistentVolumeController, expectedDeleteCalls []error) {
	plugin := &mockVolumePlugin{
		deleteCalls: expectedDeleteCalls,
	}
	ctrl.recyclePluginMgr.InitPlugins([]vol.VolumePlugin{plugin}, ctrl)
}

// newVolume returns a new volume with given attributes
func newVolume(name, capacity, boundToClaimUID, boundToClaimName string, phase api.PersistentVolumePhase, reclaimPolicy api.PersistentVolumeReclaimPolicy, annotations ...string) *api.PersistentVolume {
	volume := api.PersistentVolume{
		ObjectMeta: api.ObjectMeta{
			Name:            name,
			ResourceVersion: "1",
		},
		Spec: api.PersistentVolumeSpec{
			Capacity: api.ResourceList{
				api.ResourceName(api.ResourceStorage): resource.MustParse(capacity),
			},
			PersistentVolumeSource: api.PersistentVolumeSource{
				GCEPersistentDisk: &api.GCEPersistentDiskVolumeSource{},
			},
			AccessModes:                   []api.PersistentVolumeAccessMode{api.ReadWriteOnce, api.ReadOnlyMany},
			PersistentVolumeReclaimPolicy: reclaimPolicy,
		},
		Status: api.PersistentVolumeStatus{
			Phase: phase,
		},
	}

	if boundToClaimName != "" {
		volume.Spec.ClaimRef = &api.ObjectReference{
			Kind:       "PersistentVolumeClaim",
			APIVersion: "v1",
			UID:        types.UID(boundToClaimUID),
			Namespace:  testNamespace,
			Name:       boundToClaimName,
		}
	}

	if len(annotations) > 0 {
		volume.Annotations = make(map[string]string)
		for _, a := range annotations {
			volume.Annotations[a] = "yes"
		}
	}

	return &volume
}

// newVolumeArray returns array with a single volume that would be returned by
// newVolume() with the same parameters.
func newVolumeArray(name, capacity, boundToClaimUID, boundToClaimName string, phase api.PersistentVolumePhase, reclaimPolicy api.PersistentVolumeReclaimPolicy, annotations ...string) []*api.PersistentVolume {
	return []*api.PersistentVolume{
		newVolume(name, capacity, boundToClaimUID, boundToClaimName, phase, reclaimPolicy, annotations...),
	}
}

// newClaim returns a new claim with given attributes
func newClaim(name, claimUID, capacity, boundToVolume string, phase api.PersistentVolumeClaimPhase, annotations ...string) *api.PersistentVolumeClaim {
	claim := api.PersistentVolumeClaim{
		ObjectMeta: api.ObjectMeta{
			Name:            name,
			Namespace:       testNamespace,
			UID:             types.UID(claimUID),
			ResourceVersion: "1",
		},
		Spec: api.PersistentVolumeClaimSpec{
			AccessModes: []api.PersistentVolumeAccessMode{api.ReadWriteOnce, api.ReadOnlyMany},
			Resources: api.ResourceRequirements{
				Requests: api.ResourceList{
					api.ResourceName(api.ResourceStorage): resource.MustParse(capacity),
				},
			},
			VolumeName: boundToVolume,
		},
		Status: api.PersistentVolumeClaimStatus{
			Phase: phase,
		},
	}
	// Make sure api.GetReference(claim) works
	claim.ObjectMeta.SelfLink = testapi.Default.SelfLink("pvc", name)

	if len(annotations) > 0 {
		claim.Annotations = make(map[string]string)
		for _, a := range annotations {
			claim.Annotations[a] = "yes"
		}
	}
	return &claim
}

// newClaimArray returns array with a single claim that would be returned by
// newClaim() with the same parameters.
func newClaimArray(name, claimUID, capacity, boundToVolume string, phase api.PersistentVolumeClaimPhase, annotations ...string) []*api.PersistentVolumeClaim {
	return []*api.PersistentVolumeClaim{
		newClaim(name, claimUID, capacity, boundToVolume, phase, annotations...),
	}
}

func testSyncClaim(ctrl *PersistentVolumeController, reactor *volumeReactor, test controllerTest) error {
	return ctrl.syncClaim(test.initialClaims[0])
}

func testSyncClaimError(ctrl *PersistentVolumeController, reactor *volumeReactor, test controllerTest) error {
	err := ctrl.syncClaim(test.initialClaims[0])

	if err != nil {
		return nil
	}
	return fmt.Errorf("syncClaim succeeded when failure was expected")
}

func testSyncVolume(ctrl *PersistentVolumeController, reactor *volumeReactor, test controllerTest) error {
	return ctrl.syncVolume(test.initialVolumes[0])
}

type operationType string

const operationDelete = "Delete"
const operationRecycle = "Recycle"

// wrapTestWithControllerConfig returns a testCall that:
// - configures controller with recycler or deleter which will return provided
//   errors when a volume is deleted or recycled.
// - calls given testCall
func wrapTestWithControllerConfig(operation operationType, expectedOperationCalls []error, toWrap testCall) testCall {
	expected := expectedOperationCalls

	return func(ctrl *PersistentVolumeController, reactor *volumeReactor, test controllerTest) error {
		switch operation {
		case operationDelete:
			addDeletePlugin(ctrl, expected)
		case operationRecycle:
			addRecyclePlugin(ctrl, expected)
		}

		return toWrap(ctrl, reactor, test)
	}
}

// wrapTestWithInjectedOperation returns a testCall that:
// - starts the controller and lets it run original testCall until
//   scheduleOperation() call. It blocks the controller there and calls the
//   injected function to simulate that something is happenning when the
//   controller waits for the operation lock. Controller is then resumed and we
//   check how it behaves.
func wrapTestWithInjectedOperation(toWrap testCall, injectBeforeOperation func(ctrl *PersistentVolumeController, reactor *volumeReactor)) testCall {

	return func(ctrl *PersistentVolumeController, reactor *volumeReactor, test controllerTest) error {
		// Inject a hook before async operation starts
		ctrl.preOperationHook = func(operationName string, arg interface{}) {
			// Inside the hook, run the function to inject
			glog.V(4).Infof("reactor: scheduleOperation reached, injecting call")
			injectBeforeOperation(ctrl, reactor)
		}

		// Run the tested function (typically syncClaim/syncVolume) in a
		// separate goroutine.
		var testError error
		var testFinished int32

		go func() {
			testError = toWrap(ctrl, reactor, test)
			// Let the "main" test function know that syncVolume has finished.
			atomic.StoreInt32(&testFinished, 1)
		}()

		// Wait for the controler to finish the test function.
		for atomic.LoadInt32(&testFinished) == 0 {
			time.Sleep(time.Millisecond * 10)
		}

		return testError
	}
}

func evaluateTestResults(ctrl *PersistentVolumeController, reactor *volumeReactor, test controllerTest, t *testing.T) {
	// Evaluate results
	if err := reactor.checkClaims(t, test.expectedClaims); err != nil {
		t.Errorf("Test %q: %v", test.name, err)

	}
	if err := reactor.checkVolumes(t, test.expectedVolumes); err != nil {
		t.Errorf("Test %q: %v", test.name, err)
	}

	if err := checkEvents(t, test.expectedEvents, ctrl); err != nil {
		t.Errorf("Test %q: %v", test.name, err)
	}
}

// Test single call to syncClaim and syncVolume methods.
// For all tests:
// 1. Fill in the controller with initial data
// 2. Call the tested function (syncClaim/syncVolume) via
//    controllerTest.testCall *once*.
// 3. Compare resulting volumes and claims with expected volumes and claims.
func runSyncTests(t *testing.T, tests []controllerTest) {
	for _, test := range tests {
		glog.V(4).Infof("starting test %q", test.name)

		// Initialize the controller
		client := &fake.Clientset{}
		ctrl := newPersistentVolumeController(client)
		reactor := newVolumeReactor(client, ctrl, nil, nil)
		for _, claim := range test.initialClaims {
			ctrl.claims.Add(claim)
			reactor.claims[claim.Name] = claim
		}
		for _, volume := range test.initialVolumes {
			ctrl.volumes.store.Add(volume)
			reactor.volumes[volume.Name] = volume
		}

		// Run the tested functions
		err := test.test(ctrl, reactor, test)
		if err != nil {
			t.Errorf("Test %q failed: %v", test.name, err)
		}

		// Wait for all goroutines to finish
		reactor.waitTest()

		evaluateTestResults(ctrl, reactor, test, t)
	}
}

// Test multiple calls to syncClaim/syncVolume and periodic sync of all
// volume/claims. For all tests, the test follows this pattern:
// 0. Load the controller with initial data.
// 1. Call controllerTest.testCall() once as in TestSync()
// 2. For all volumes/claims changed by previous syncVolume/syncClaim calls,
//    call appropriate syncVolume/syncClaim (simulating "volume/claim changed"
//    events). Go to 2. if these calls change anything.
// 3. When all changes are processed and no new changes were made, call
//    syncVolume/syncClaim on all volumes/claims (simulating "periodic sync").
// 4. If some changes were done by step 3., go to 2. (simulation of
//    "volume/claim updated" events, eventually performing step 3. again)
// 5. When 3. does not do any changes, finish the tests and compare final set
//    of volumes/claims with expected claims/volumes and report differences.
// Some limit of calls in enforced to prevent endless loops.
func runMultisyncTests(t *testing.T, tests []controllerTest) {
	for _, test := range tests {
		glog.V(4).Infof("starting multisync test %q", test.name)

		// Initialize the controller
		client := &fake.Clientset{}
		ctrl := newPersistentVolumeController(client)
		reactor := newVolumeReactor(client, ctrl, nil, nil)
		for _, claim := range test.initialClaims {
			ctrl.claims.Add(claim)
			reactor.claims[claim.Name] = claim
		}
		for _, volume := range test.initialVolumes {
			ctrl.volumes.store.Add(volume)
			reactor.volumes[volume.Name] = volume
		}

		// Run the tested function
		err := test.test(ctrl, reactor, test)
		if err != nil {
			t.Errorf("Test %q failed: %v", test.name, err)
		}

		// Simulate any "changed" events and "periodical sync" until we reach a
		// stable state.
		firstSync := true
		counter := 0
		for {
			counter++
			glog.V(4).Infof("test %q: iteration %d", test.name, counter)

			if counter > 100 {
				t.Errorf("Test %q failed: too many iterations", test.name)
				break
			}

			// Wait for all goroutines to finish
			reactor.waitTest()

			obj := reactor.popChange()
			if obj == nil {
				// Nothing was changed, should we exit?
				if firstSync || reactor.changedSinceLastSync > 0 {
					// There were some changes after the last "periodic sync".
					// Simulate "periodic sync" of everything (until it produces
					// no changes).
					firstSync = false
					glog.V(4).Infof("test %q: simulating periodical sync of all claims and volumes", test.name)
					reactor.syncAll()
				} else {
					// Last sync did not produce any updates, the test reached
					// stable state -> finish.
					break
				}
			}

			// There were some changes, process them
			switch obj.(type) {
			case *api.PersistentVolumeClaim:
				claim := obj.(*api.PersistentVolumeClaim)
				// Simulate "claim updated" event
				ctrl.claims.Update(claim)
				err = ctrl.syncClaim(claim)
				if err != nil {
					if err == versionConflictError {
						// Ignore version errors
						glog.V(4).Infof("test intentionaly ignores version error.")
					} else {
						t.Errorf("Error calling syncClaim: %v", err)
						// Finish the loop on the first error
						break
					}
				}
				// Process generated changes
				continue
			case *api.PersistentVolume:
				volume := obj.(*api.PersistentVolume)
				// Simulate "volume updated" event
				ctrl.volumes.store.Update(volume)
				err = ctrl.syncVolume(volume)
				if err != nil {
					if err == versionConflictError {
						// Ignore version errors
						glog.V(4).Infof("test intentionaly ignores version error.")
					} else {
						t.Errorf("Error calling syncVolume: %v", err)
						// Finish the loop on the first error
						break
					}
				}
				// Process generated changes
				continue
			}
		}
		evaluateTestResults(ctrl, reactor, test, t)
		glog.V(4).Infof("test %q finished after %d iterations", test.name, counter)
	}
}

// Dummy volume plugin for provisioning, deletion and recycling. It contains
// lists of expected return values to simulate errors.
type mockVolumePlugin struct {
	provisionCalls       []error
	provisionCallCounter int
	deleteCalls          []error
	deleteCallCounter    int
	recycleCalls         []error
	recycleCallCounter   int
}

var _ vol.VolumePlugin = &mockVolumePlugin{}

func (plugin *mockVolumePlugin) Init(host vol.VolumeHost) error {
	return nil
}

func (plugin *mockVolumePlugin) Name() string {
	return "mockVolumePlugin"
}

func (plugin *mockVolumePlugin) CanSupport(spec *vol.Spec) bool {
	return true
}

func (plugin *mockVolumePlugin) NewMounter(spec *vol.Spec, podRef *api.Pod, opts vol.VolumeOptions) (vol.Mounter, error) {
	return nil, fmt.Errorf("Mounter is not supported by this plugin")
}

func (plugin *mockVolumePlugin) NewUnmounter(name string, podUID types.UID) (vol.Unmounter, error) {
	return nil, fmt.Errorf("Unmounter is not supported by this plugin")
}

// Provisioner interfaces

func (plugin *mockVolumePlugin) NewProvisioner(options vol.VolumeOptions) (vol.Provisioner, error) {
	if len(plugin.provisionCalls) > 0 {
		// mockVolumePlugin directly implements Provisioner interface
		glog.V(4).Infof("mock plugin NewProvisioner called, returning mock provisioner")
		return plugin, nil
	} else {
		return nil, fmt.Errorf("Mock plugin error: no provisionCalls configured")
	}
}

func (plugin *mockVolumePlugin) Provision(*api.PersistentVolume) error {
	if len(plugin.provisionCalls) <= plugin.provisionCallCounter {
		return fmt.Errorf("Mock plugin error: unexpected provisioner call %d", plugin.provisionCallCounter)
	}
	ret := plugin.provisionCalls[plugin.provisionCallCounter]
	plugin.provisionCallCounter++
	glog.V(4).Infof("mock plugin Provision call nr. %d, returning %v", plugin.provisionCallCounter, ret)
	return ret
}

func (plugin *mockVolumePlugin) NewPersistentVolumeTemplate() (*api.PersistentVolume, error) {
	if len(plugin.provisionCalls) <= plugin.provisionCallCounter {
		return nil, fmt.Errorf("Mock plugin error: unexpected provisioner call %d", plugin.provisionCallCounter)
	}
	ret := plugin.provisionCalls[plugin.provisionCallCounter]
	plugin.provisionCallCounter++
	glog.V(4).Infof("mock plugin NewPersistentVolumeTemplate call nr. %d, returning %v", plugin.provisionCallCounter, ret)
	return nil, ret
}

// Deleter interfaces

func (plugin *mockVolumePlugin) NewDeleter(spec *vol.Spec) (vol.Deleter, error) {
	if len(plugin.deleteCalls) > 0 {
		// mockVolumePlugin directly implements Deleter interface
		glog.V(4).Infof("mock plugin NewDeleter called, returning mock deleter")
		return plugin, nil
	} else {
		return nil, fmt.Errorf("Mock plugin error: no deleteCalls configured")
	}
}

func (plugin *mockVolumePlugin) Delete() error {
	if len(plugin.deleteCalls) <= plugin.deleteCallCounter {
		return fmt.Errorf("Mock plugin error: unexpected deleter call %d", plugin.deleteCallCounter)
	}
	ret := plugin.deleteCalls[plugin.deleteCallCounter]
	plugin.deleteCallCounter++
	glog.V(4).Infof("mock plugin Delete call nr. %d, returning %v", plugin.deleteCallCounter, ret)
	return ret
}

// Volume interfaces

func (plugin *mockVolumePlugin) GetPath() string {
	return ""
}

func (plugin *mockVolumePlugin) GetMetrics() (*vol.Metrics, error) {
	return nil, nil
}

// Recycler interfaces

func (plugin *mockVolumePlugin) NewRecycler(spec *vol.Spec) (vol.Recycler, error) {
	if len(plugin.recycleCalls) > 0 {
		// mockVolumePlugin directly implements Recycler interface
		glog.V(4).Infof("mock plugin NewRecycler called, returning mock recycler")
		return plugin, nil
	} else {
		return nil, fmt.Errorf("Mock plugin error: no recycleCalls configured")
	}
}

func (plugin *mockVolumePlugin) Recycle() error {
	if len(plugin.recycleCalls) <= plugin.recycleCallCounter {
		return fmt.Errorf("Mock plugin error: unexpected recycle call %d", plugin.recycleCallCounter)
	}
	ret := plugin.recycleCalls[plugin.recycleCallCounter]
	plugin.recycleCallCounter++
	glog.V(4).Infof("mock plugin Recycle call nr. %d, returning %v", plugin.recycleCallCounter, ret)
	return ret
}