Support named states in inmeme backend

Used to expand test coverage

backend/remote-state/inmem/backend.go

@@ -2,21 +2,33 @@ package inmem
 
 import (
 	"context"
+	"errors"
+	"fmt"
+	"sort"
+	"sync"
+	"time"
 
 	"github.com/hashicorp/terraform/backend"
-	"github.com/hashicorp/terraform/backend/remote-state"
 	"github.com/hashicorp/terraform/helper/schema"
 	"github.com/hashicorp/terraform/state"
 	"github.com/hashicorp/terraform/state/remote"
 )
 
+// we keep the states and locks in package-level variables, so that they can be
+// accessed from multiple instances of the backend. This better emulates
+// backend instances accessing a single remote data store.
+var states = stateMap{
+	m: map[string]*remote.State{},
+}
+
+var locks = lockMap{
+	m: map[string]*state.LockInfo{},
+}
+
 // New creates a new backend for Inmem remote state.
 func New() backend.Backend {
-	return &remotestate.Backend{
-		ConfigureFunc: configure,
-
 	// Set the schema
-		Backend: &schema.Backend{
+	s := &schema.Backend{
 		Schema: map[string]*schema.Schema{
 			"lock_id": &schema.Schema{
 				Type:        schema.TypeString,
@@ -24,18 +36,138 @@ func New() backend.Backend {
 				Description: "initializes the state in a locked configuration",
 			},
 		},
-		},
 	}
+	backend := &Backend{Backend: s}
+	backend.Backend.ConfigureFunc = backend.configure
+	return backend
 }
 
-func configure(ctx context.Context) (remote.Client, error) {
+type Backend struct {
+	*schema.Backend
+}
+
+func (b *Backend) configure(ctx context.Context) error {
+	states.Lock()
+	defer states.Unlock()
+
+	defaultClient := &RemoteClient{
+		Name: backend.DefaultStateName,
+	}
+
+	states.m[backend.DefaultStateName] = &remote.State{
+		Client: defaultClient,
+	}
+
+	// set the default client lock info per the test config
 	data := schema.FromContextBackendConfig(ctx)
 	if v, ok := data.GetOk("lock_id"); ok && v.(string) != "" {
 		info := state.NewLockInfo()
 		info.ID = v.(string)
 		info.Operation = "test"
 		info.Info = "test config"
-		return &RemoteClient{LockInfo: info}, nil
+
+		locks.lock(backend.DefaultStateName, info)
 	}
-	return &RemoteClient{}, nil
+
+	return nil
+}
+
+func (b *Backend) States() ([]string, error) {
+	states.Lock()
+	defer states.Unlock()
+
+	var workspaces []string
+
+	for s := range states.m {
+		workspaces = append(workspaces, s)
+	}
+
+	sort.Strings(workspaces)
+	return workspaces, nil
+}
+
+func (b *Backend) DeleteState(name string) error {
+	states.Lock()
+	defer states.Unlock()
+
+	if name == backend.DefaultStateName || name == "" {
+		return fmt.Errorf("can't delete default state")
+	}
+
+	delete(states.m, name)
+	return nil
+}
+
+func (b *Backend) State(name string) (state.State, error) {
+	states.Lock()
+	defer states.Unlock()
+
+	s := states.m[name]
+	if s == nil {
+		s = &remote.State{
+			Client: &RemoteClient{
+				Name: name,
+			},
+		}
+		states.m[name] = s
+	}
+
+	return s, nil
+}
+
+type stateMap struct {
+	sync.Mutex
+	m map[string]*remote.State
+}
+
+// Global level locks for inmem backends.
+type lockMap struct {
+	sync.Mutex
+	m map[string]*state.LockInfo
+}
+
+func (l *lockMap) lock(name string, info *state.LockInfo) (string, error) {
+	l.Lock()
+	defer l.Unlock()
+
+	lockInfo := l.m[name]
+	if lockInfo != nil {
+		lockErr := &state.LockError{
+			Info: lockInfo,
+		}
+
+		lockErr.Err = errors.New("state locked")
+		// make a copy of the lock info to avoid any testing shenanigans
+		*lockErr.Info = *lockInfo
+		return "", lockErr
+	}
+
+	info.Created = time.Now().UTC()
+	l.m[name] = info
+
+	return info.ID, nil
+}
+
+func (l *lockMap) unlock(name, id string) error {
+	l.Lock()
+	defer l.Unlock()
+
+	lockInfo := l.m[name]
+
+	if lockInfo == nil {
+		return errors.New("state not locked")
+	}
+
+	lockErr := &state.LockError{
+		Info: &state.LockInfo{},
+	}
+
+	if id != lockInfo.ID {
+		lockErr.Err = errors.New("invalid lock id")
+		*lockErr.Info = *lockInfo
+		return lockErr
+	}
+
+	delete(l.m, name)
+	return nil
 }

backend/remote-state/inmem/backend_test.go

@@ -0,0 +1,63 @@
+package inmem
+
+import (
+	"testing"
+
+	"github.com/hashicorp/terraform/backend"
+	"github.com/hashicorp/terraform/state"
+	"github.com/hashicorp/terraform/state/remote"
+)
+
+func TestBackend_impl(t *testing.T) {
+	var _ backend.Backend = new(Backend)
+}
+
+// reset the states and locks between tests
+func reset() {
+	states = stateMap{
+		m: map[string]*remote.State{},
+	}
+
+	locks = lockMap{
+		m: map[string]*state.LockInfo{},
+	}
+}
+
+func TestBackendConfig(t *testing.T) {
+	defer reset()
+	testID := "test_lock_id"
+
+	config := map[string]interface{}{
+		"lock_id": testID,
+	}
+
+	b := backend.TestBackendConfig(t, New(), config).(*Backend)
+
+	s, err := b.State(backend.DefaultStateName)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	c := s.(*remote.State).Client.(*RemoteClient)
+	if c.Name != backend.DefaultStateName {
+		t.Fatal("client name is not configured")
+	}
+
+	if err := locks.unlock(backend.DefaultStateName, testID); err != nil {
+		t.Fatalf("default state should have been locked: %s", err)
+	}
+}
+
+func TestBackend(t *testing.T) {
+	defer reset()
+	b := backend.TestBackendConfig(t, New(), nil).(*Backend)
+	backend.TestBackend(t, b, nil)
+}
+
+func TestBackendLocked(t *testing.T) {
+	defer reset()
+	b1 := backend.TestBackendConfig(t, New(), nil).(*Backend)
+	b2 := backend.TestBackendConfig(t, New(), nil).(*Backend)
+
+	backend.TestBackend(t, b1, b2)
+}

backend/remote-state/inmem/client.go

@@ -2,8 +2,6 @@ package inmem
 
 import (
 	"crypto/md5"
-	"errors"
-	"time"
 
 	"github.com/hashicorp/terraform/state"
 	"github.com/hashicorp/terraform/state/remote"
@@ -13,8 +11,7 @@ import (
 type RemoteClient struct {
 	Data []byte
 	MD5  []byte
-
-	LockInfo *state.LockInfo
+	Name string
 }
 
 func (c *RemoteClient) Get() (*remote.Payload, error) {
@@ -43,37 +40,8 @@ func (c *RemoteClient) Delete() error {
 }
 
 func (c *RemoteClient) Lock(info *state.LockInfo) (string, error) {
-	lockErr := &state.LockError{
-		Info: &state.LockInfo{},
-	}
-
-	if c.LockInfo != nil {
-		lockErr.Err = errors.New("state locked")
-		// make a copy of the lock info to avoid any testing shenanigans
-		*lockErr.Info = *c.LockInfo
-		return "", lockErr
-	}
-
-	info.Created = time.Now().UTC()
-	c.LockInfo = info
-
-	return c.LockInfo.ID, nil
+	return locks.lock(c.Name, info)
 }
-
 func (c *RemoteClient) Unlock(id string) error {
-	if c.LockInfo == nil {
-		return errors.New("state not locked")
-	}
-
-	lockErr := &state.LockError{
-		Info: &state.LockInfo{},
-	}
-	if id != c.LockInfo.ID {
-		lockErr.Err = errors.New("invalid lock id")
-		*lockErr.Info = *c.LockInfo
-		return lockErr
-	}
-
-	c.LockInfo = nil
-	return nil
+	return locks.unlock(c.Name, id)
 }

backend/remote-state/inmem/client_test.go

@@ -4,7 +4,6 @@ import (
 	"testing"
 
 	"github.com/hashicorp/terraform/backend"
-	remotestate "github.com/hashicorp/terraform/backend/remote-state"
 	"github.com/hashicorp/terraform/state/remote"
 )
 
@@ -14,11 +13,19 @@ func TestRemoteClient_impl(t *testing.T) {
 }
 
 func TestRemoteClient(t *testing.T) {
+	defer reset()
 	b := backend.TestBackendConfig(t, New(), nil)
-	remotestate.TestClient(t, b)
+
+	s, err := b.State(backend.DefaultStateName)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	remote.TestClient(t, s.(*remote.State).Client)
 }
 
 func TestInmemLocks(t *testing.T) {
+	defer reset()
 	s, err := backend.TestBackendConfig(t, New(), nil).State(backend.DefaultStateName)
 	if err != nil {
 		t.Fatal(err)