chore: add lots of interface assertions

autobatch/autobatch.go

@@ -19,6 +19,9 @@ type Datastore struct {
 	maxBufferEntries int
 }
 
+var _ ds.Datastore = (*Datastore)(nil)
+var _ ds.PersistentDatastore = (*Datastore)(nil)
+
 type op struct {
 	delete bool
 	value  []byte

basic_ds.go

@@ -14,6 +14,9 @@ type MapDatastore struct {
 	values map[Key][]byte
 }
 
+var _ Datastore = (*MapDatastore)(nil)
+var _ Batching = (*MapDatastore)(nil)
+
 // NewMapDatastore constructs a MapDatastore. It is _not_ thread-safe by
 // default, wrap using sync.MutexWrap if you need thread safety (the answer here
 // is usually yes).
@@ -91,6 +94,9 @@ func (d *MapDatastore) Close() error {
 type NullDatastore struct {
 }
 
+var _ Datastore = (*NullDatastore)(nil)
+var _ Batching = (*NullDatastore)(nil)
+
 // NewNullDatastore constructs a null datastoe
 func NewNullDatastore() *NullDatastore {
 	return &NullDatastore{}
@@ -145,6 +151,14 @@ type LogDatastore struct {
 	child Datastore
 }
 
+var _ Datastore = (*LogDatastore)(nil)
+var _ Batching = (*LogDatastore)(nil)
+var _ GCDatastore = (*LogDatastore)(nil)
+var _ PersistentDatastore = (*LogDatastore)(nil)
+var _ ScrubbedDatastore = (*LogDatastore)(nil)
+var _ CheckedDatastore = (*LogDatastore)(nil)
+var _ Shim = (*LogDatastore)(nil)
+
 // Shim is a datastore which has a child.
 type Shim interface {
 	Datastore
@@ -226,6 +240,8 @@ type LogBatch struct {
 	child Batch
 }
 
+var _ Batch = (*LogBatch)(nil)
+
 func (d *LogDatastore) Batch(ctx context.Context) (Batch, error) {
 	log.Printf("%s: Batch\n", d.Name)
 	if bds, ok := d.child.(Batching); ok {

batch.go

@@ -17,6 +17,8 @@ type basicBatch struct {
 	target Datastore
 }
 
+var _ Batch = (*basicBatch)(nil)
+
 func NewBasicBatch(ds Datastore) Batch {
 	return &basicBatch{
 		ops:    make(map[Key]op),

delayed/delayed.go

@@ -22,7 +22,9 @@ type Delayed struct {
 	delay delay.D
 }
 
+var _ ds.Datastore = (*Delayed)(nil)
 var _ ds.Batching = (*Delayed)(nil)
+var _ ds.PersistentDatastore = (*Delayed)(nil)
 var _ io.Closer = (*Delayed)(nil)
 
 // Put implements the ds.Datastore interface.

examples/fs.go

@@ -37,6 +37,10 @@ type Datastore struct {
 	path string
 }
 
+var _ ds.Datastore = (*Datastore)(nil)
+var _ ds.Batching = (*Datastore)(nil)
+var _ ds.PersistentDatastore = (*Datastore)(nil)
+
 // NewDatastore returns a new fs Datastore at given `path`
 func NewDatastore(path string) (ds.Datastore, error) {
 	if !isDir(path) {

failstore/failstore.go

@@ -17,6 +17,10 @@ type Failstore struct {
 	errfunc func(string) error
 }
 
+var _ ds.Datastore = (*Failstore)(nil)
+var _ ds.Batching = (*Failstore)(nil)
+var _ ds.PersistentDatastore = (*Failstore)(nil)
+
 // NewFailstore creates a new datastore with the given error function.
 // The efunc will be called with different strings depending on the
 // datastore function: put, get, has, delete, query, batch, batch-put,
@@ -117,6 +121,8 @@ type FailBatch struct {
 	dstore *Failstore
 }
 
+var _ ds.Batch = (*FailBatch)(nil)
+
 // Batch returns a new Batch Failstore.
 func (d *Failstore) Batch(ctx context.Context) (ds.Batch, error) {
 	if err := d.errfunc("batch"); err != nil {

keytransform/keytransform.go

@@ -29,6 +29,14 @@ type Datastore struct {
 	KeyTransform
 }
 
+var _ ds.Datastore = (*Datastore)(nil)
+var _ ds.Batching = (*Datastore)(nil)
+var _ ds.Shim = (*Datastore)(nil)
+var _ ds.PersistentDatastore = (*Datastore)(nil)
+var _ ds.CheckedDatastore = (*Datastore)(nil)
+var _ ds.ScrubbedDatastore = (*Datastore)(nil)
+var _ ds.GCDatastore = (*Datastore)(nil)
+
 // Children implements ds.Shim
 func (d *Datastore) Children() []ds.Datastore {
 	return []ds.Datastore{d.child}
@@ -222,6 +230,8 @@ type transformBatch struct {
 	f KeyMapping
 }
 
+var _ ds.Batch = (*transformBatch)(nil)
+
 func (t *transformBatch) Put(ctx context.Context, key ds.Key, val []byte) error {
 	return t.dst.Put(ctx, t.f(key), val)
 }
@@ -254,9 +264,3 @@ func (d *Datastore) CollectGarbage(ctx context.Context) error {
 	}
 	return nil
 }
-
-var _ ds.Datastore = (*Datastore)(nil)
-var _ ds.GCDatastore = (*Datastore)(nil)
-var _ ds.Batching = (*Datastore)(nil)
-var _ ds.PersistentDatastore = (*Datastore)(nil)
-var _ ds.ScrubbedDatastore = (*Datastore)(nil)

mount/mount.go

@@ -69,6 +69,11 @@ type Datastore struct {
 }
 
 var _ ds.Datastore = (*Datastore)(nil)
+var _ ds.Batching = (*Datastore)(nil)
+var _ ds.PersistentDatastore = (*Datastore)(nil)
+var _ ds.CheckedDatastore = (*Datastore)(nil)
+var _ ds.ScrubbedDatastore = (*Datastore)(nil)
+var _ ds.GCDatastore = (*Datastore)(nil)
 
 // lookup looks up the datastore in which the given key lives.
 func (d *Datastore) lookup(key ds.Key) (ds.Datastore, ds.Key, ds.Key) {
@@ -406,6 +411,8 @@ type mountBatch struct {
 	d *Datastore
 }
 
+var _ ds.Batch = (*mountBatch)(nil)
+
 // Batch returns a batch that operates over all mounted datastores.
 func (d *Datastore) Batch(ctx context.Context) (ds.Batch, error) {
 	return &mountBatch{

retrystore/retrystore.go

@@ -24,6 +24,10 @@ type Datastore struct {
 	ds.Batching
 }
 
+var _ ds.Datastore = (*Datastore)(nil)
+var _ ds.Batching = (*Datastore)(nil)
+var _ ds.PersistentDatastore = (*Datastore)(nil)
+
 var errFmtString = "ran out of retries trying to get past temporary error: %w"
 
 func (d *Datastore) runOp(op func() error) error {

sync/sync.go

@@ -16,6 +16,14 @@ type MutexDatastore struct {
 	child ds.Datastore
 }
 
+var _ ds.Datastore = (*MutexDatastore)(nil)
+var _ ds.Batching = (*MutexDatastore)(nil)
+var _ ds.Shim = (*MutexDatastore)(nil)
+var _ ds.PersistentDatastore = (*MutexDatastore)(nil)
+var _ ds.CheckedDatastore = (*MutexDatastore)(nil)
+var _ ds.ScrubbedDatastore = (*MutexDatastore)(nil)
+var _ ds.GCDatastore = (*MutexDatastore)(nil)
+
 // MutexWrap constructs a datastore with a coarse lock around the entire
 // datastore, for every single operation.
 func MutexWrap(d ds.Datastore) *MutexDatastore {
@@ -129,6 +137,8 @@ type syncBatch struct {
 	mds   *MutexDatastore
 }
 
+var _ ds.Batch = (*syncBatch)(nil)
+
 func (b *syncBatch) Put(ctx context.Context, key ds.Key, val []byte) error {
 	b.mds.Lock()
 	defer b.mds.Unlock()