diff --git a/backend/generic.go b/backend/generic.go
index 6e09729b3..e5509f334 100644
--- a/backend/generic.go
+++ b/backend/generic.go
@@ -8,15 +8,12 @@ import (
 	"errors"
 	"io/ioutil"
 	"sort"
-	"sync"
 )
 
 const (
 	MinPrefixLength = 4
 )
 
-var idPool = sync.Pool{New: func() interface{} { return ID(make([]byte, IDSize)) }}
-
 var (
 	ErrNoIDPrefixFound   = errors.New("no ID found")
 	ErrMultipleIDMatches = errors.New("multiple IDs with prefix found")
@@ -24,7 +21,10 @@ var (
 
 // Each lists all entries of type t in the backend and calls function f() with
 // the id and data.
-func Each(be Server, t Type, f func(id ID, data []byte, err error)) error {
+func Each(be interface {
+	lister
+	getter
+}, t Type, f func(id ID, data []byte, err error)) error {
 	ids, err := be.List(t)
 	if err != nil {
 		return err
@@ -45,7 +45,7 @@ func Each(be Server, t Type, f func(id ID, data []byte, err error)) error {
 
 // Each lists all entries of type t in the backend and calls function f() with
 // the id.
-func EachID(be Server, t Type, f func(ID)) error {
+func EachID(be lister, t Type, f func(ID)) error {
 	ids, err := be.List(t)
 	if err != nil {
 		return err
@@ -101,7 +101,7 @@ func Hash(data []byte) ID {
 // Find loads the list of all blobs of type t and searches for IDs which start
 // with prefix. If none is found, nil and ErrNoIDPrefixFound is returned. If
 // more than one is found, nil and ErrMultipleIDMatches is returned.
-func Find(be Server, t Type, prefix string) (ID, error) {
+func Find(be lister, t Type, prefix string) (ID, error) {
 	p, err := hex.DecodeString(prefix)
 	if err != nil {
 		return nil, err
@@ -134,7 +134,7 @@ func Find(be Server, t Type, prefix string) (ID, error) {
 
 // FindSnapshot takes a string and tries to find a snapshot whose ID matches
 // the string as closely as possible.
-func FindSnapshot(be Server, s string) (ID, error) {
+func FindSnapshot(be lister, s string) (ID, error) {
 	// parse ID directly
 	if id, err := ParseID(s); err == nil {
 		return id, nil
@@ -151,7 +151,7 @@ func FindSnapshot(be Server, s string) (ID, error) {
 
 // PrefixLength returns the number of bytes required so that all prefixes of
 // all IDs of type t are unique.
-func PrefixLength(be Lister, t Type) (int, error) {
+func PrefixLength(be lister, t Type) (int, error) {
 	// load all IDs of the given type
 	list, err := be.List(t)
 	if err != nil {
diff --git a/backend/generic_test.go b/backend/generic_test.go
index 6deb9a07f..2d6aff550 100644
--- a/backend/generic_test.go
+++ b/backend/generic_test.go
@@ -46,9 +46,40 @@ func str2id(s string) backend.ID {
 	return id
 }
 
-type IDList backend.IDs
+type mockBackend struct {
+	list   func(backend.Type) (backend.IDs, error)
+	get    func(backend.Type, backend.ID) ([]byte, error)
+	create func(backend.Type, []byte) (backend.ID, error)
+	test   func(backend.Type, backend.ID) (bool, error)
+	remove func(backend.Type, backend.ID) error
+	close  func() error
+}
 
-var samples = IDList{
+func (m mockBackend) List(t backend.Type) (backend.IDs, error) {
+	return m.list(t)
+}
+
+func (m mockBackend) Get(t backend.Type, id backend.ID) ([]byte, error) {
+	return m.get(t, id)
+}
+
+func (m mockBackend) Create(t backend.Type, data []byte) (backend.ID, error) {
+	return m.create(t, data)
+}
+
+func (m mockBackend) Test(t backend.Type, id backend.ID) (bool, error) {
+	return m.test(t, id)
+}
+
+func (m mockBackend) Remove(t backend.Type, id backend.ID) error {
+	return m.remove(t, id)
+}
+
+func (m mockBackend) Close() error {
+	return m.close()
+}
+
+var samples = backend.IDs{
 	str2id("20bdc1402a6fc9b633aaffffffffffffffffffffffffffffffffffffffffffff"),
 	str2id("20bdc1402a6fc9b633ccd578c4a92d0f4ef1a457fa2e16c596bc73fb409d6cc0"),
 	str2id("20bdc1402a6fc9b633ffffffffffffffffffffffffffffffffffffffffffffff"),
@@ -59,20 +90,25 @@ var samples = IDList{
 	str2id("fa31d65b87affcd167b119e9d3d2a27b8236ca4836cb077ed3e96fcbe209b792"),
 }
 
-func (l IDList) List(backend.Type) (backend.IDs, error) {
-	return backend.IDs(l), nil
-}
-
 func TestPrefixLength(t *testing.T) {
-	l, err := backend.PrefixLength(samples, backend.Snapshot)
+	list := samples
+
+	m := mockBackend{}
+	m.list = func(t backend.Type) (backend.IDs, error) {
+		return list, nil
+	}
+
+	l, err := backend.PrefixLength(m, backend.Snapshot)
 	ok(t, err)
 	equals(t, 10, l)
 
-	l, err = backend.PrefixLength(samples[:3], backend.Snapshot)
+	list = samples[:3]
+	l, err = backend.PrefixLength(m, backend.Snapshot)
 	ok(t, err)
 	equals(t, 10, l)
 
-	l, err = backend.PrefixLength(samples[3:], backend.Snapshot)
+	list = samples[3:]
+	l, err = backend.PrefixLength(m, backend.Snapshot)
 	ok(t, err)
 	equals(t, 4, l)
 }
diff --git a/backend/id.go b/backend/id.go
index 87071e577..4db643ae2 100644
--- a/backend/id.go
+++ b/backend/id.go
@@ -6,6 +6,7 @@ import (
 	"encoding/hex"
 	"encoding/json"
 	"errors"
+	"sync"
 )
 
 // IDSize contains the size of an ID, in bytes.
@@ -14,6 +15,8 @@ const IDSize = sha256.Size
 // References content within a repository.
 type ID []byte
 
+var idPool = sync.Pool{New: func() interface{} { return ID(make([]byte, IDSize)) }}
+
 // ParseID converts the given string to an ID.
 func ParseID(s string) (ID, error) {
 	b, err := hex.DecodeString(s)
diff --git a/backend/interface.go b/backend/interface.go
index ec1abb3a3..644ab9653 100644
--- a/backend/interface.go
+++ b/backend/interface.go
@@ -21,19 +21,43 @@ var (
 	ErrAlreadyPresent = errors.New("blob is already present in backend")
 )
 
-type Lister interface {
+type lister interface {
 	List(Type) (IDs, error)
 }
 
-type Server interface {
-	Create(Type, []byte) (ID, error)
+type getter interface {
 	Get(Type, ID) ([]byte, error)
-	Lister
+}
+
+type creater interface {
+	Create(Type, []byte) (ID, error)
+}
+
+type tester interface {
 	Test(Type, ID) (bool, error)
+}
+
+type remover interface {
 	Remove(Type, ID) error
-	Version() uint
+}
 
+type closer interface {
 	Close() error
+}
 
+type deleter interface {
+	Delete() error
+}
+
+type locationer interface {
 	Location() string
 }
+
+type backend interface {
+	lister
+	getter
+	creater
+	tester
+	remover
+	closer
+}
diff --git a/backend/local.go b/backend/local.go
index 0a81f1e90..68da2fe74 100644
--- a/backend/local.go
+++ b/backend/local.go
@@ -328,3 +328,8 @@ func (b *Local) Version() uint {
 func (b *Local) Close() error {
 	return nil
 }
+
+// Delete removes the repository and all files.
+func (b *Local) Delete() error {
+	return os.RemoveAll(b.p)
+}
diff --git a/backend/local_test.go b/backend/local_test.go
index b23dbee5c..e79eca5ef 100644
--- a/backend/local_test.go
+++ b/backend/local_test.go
@@ -4,7 +4,6 @@ import (
 	"flag"
 	"fmt"
 	"io/ioutil"
-	"os"
 	"sort"
 	"testing"
 
@@ -41,10 +40,10 @@ func teardownBackend(t *testing.T, b *backend.Local) {
 		return
 	}
 
-	ok(t, os.RemoveAll(b.Location()))
+	ok(t, b.Delete())
 }
 
-func testBackend(b backend.Server, t *testing.T) {
+func testBackend(b *backend.Local, t *testing.T) {
 	for _, tpe := range []backend.Type{backend.Data, backend.Key, backend.Lock, backend.Snapshot, backend.Tree, backend.Map} {
 		// detect non-existing files
 		for _, test := range TestStrings {
@@ -126,10 +125,10 @@ func TestBackend(t *testing.T) {
 	assert(t, err != nil, "opening invalid repository at /invalid-restic-test should have failed, but err is nil")
 	assert(t, b == nil, fmt.Sprintf("opening invalid repository at /invalid-restic-test should have failed, but b is not nil: %v", b))
 
-	b = setupBackend(t)
-	defer teardownBackend(t, b)
+	s := setupBackend(t)
+	defer teardownBackend(t, s)
 
-	testBackend(b, t)
+	testBackend(s, t)
 }
 
 func TestLocalBackendCreationFailures(t *testing.T) {