store: use stopper, extraxt StringStore tests

server/store/memory/string_store.go

@@ -19,11 +19,13 @@ type stringStoreDriver struct{}
 func (d *stringStoreDriver) New(_ *store.DriverConfig) (store.StringStore, error) {
 	return &stringStore{
 		strings: make(map[string]struct{}),
+		closed:  make(chan struct{}),
 	}, nil
 }
 
 type stringStore struct {
 	strings map[string]struct{}
+	closed  chan struct{}
 	sync.RWMutex
 }
 
@@ -33,6 +35,12 @@ func (ss *stringStore) PutString(s string) error {
 	ss.Lock()
 	defer ss.Unlock()
 
+	select {
+	case <-ss.closed:
+		panic("attempted to interact with stopped store")
+	default:
+	}
+
 	ss.strings[s] = struct{}{}
 
 	return nil
@@ -42,6 +50,12 @@ func (ss *stringStore) HasString(s string) (bool, error) {
 	ss.RLock()
 	defer ss.RUnlock()
 
+	select {
+	case <-ss.closed:
+		panic("attempted to interact with stopped store")
+	default:
+	}
+
 	_, ok := ss.strings[s]
 
 	return ok, nil
@@ -51,6 +65,12 @@ func (ss *stringStore) RemoveString(s string) error {
 	ss.Lock()
 	defer ss.Unlock()
 
+	select {
+	case <-ss.closed:
+		panic("attempted to interact with stopped store")
+	default:
+	}
+
 	if _, ok := ss.strings[s]; !ok {
 		return store.ErrResourceDoesNotExist
 	}
@@ -59,3 +79,15 @@ func (ss *stringStore) RemoveString(s string) error {
 
 	return nil
 }
+
+func (ss *stringStore) Stop() <-chan error {
+	toReturn := make(chan error)
+	go func() {
+		ss.Lock()
+		defer ss.Unlock()
+		ss.strings = make(map[string]struct{})
+		close(ss.closed)
+		close(toReturn)
+	}()
+	return toReturn
+}