[#1636] engine: Validate limiter release in unit tests

Signed-off-by: Dmitrii Stepanov <d.stepanov@yadro.com>

pkg/local_object_storage/engine/engine_test.go

@@ -3,8 +3,10 @@ package engine
 import (
 	"context"
 	"path/filepath"
+	"sync/atomic"
 	"testing"
 
+	"git.frostfs.info/TrueCloudLab/frostfs-node/internal/qos"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/blobovniczatree"
 	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/fstree"
@@ -90,6 +92,7 @@ func testGetDefaultShardOptions(t testing.TB) []shard.Option {
 		),
 		shard.WithPiloramaOptions(pilorama.WithPath(filepath.Join(t.TempDir(), "pilorama"))),
 		shard.WithMetaBaseOptions(testGetDefaultMetabaseOptions(t)...),
+		shard.WithLimiter(&testQoSLimiter{t: t}),
 	}
 }
 
@@ -151,3 +154,26 @@ func newTestStorages(root string, smallSize uint64) ([]blobstor.SubStorage, *tes
 		},
 	}, smallFileStorage, largeFileStorage
 }
+
+var _ qos.Limiter = (*testQoSLimiter)(nil)
+
+type testQoSLimiter struct {
+	t     testing.TB
+	read  atomic.Int64
+	write atomic.Int64
+}
+
+func (t *testQoSLimiter) Close() {
+	require.Equal(t.t, int64(0), t.read.Load(), "read requests count after limiter close must be 0")
+	require.Equal(t.t, int64(0), t.write.Load(), "write requests count after limiter close must be 0")
+}
+
+func (t *testQoSLimiter) ReadRequest(context.Context) (qos.ReleaseFunc, error) {
+	t.read.Add(1)
+	return func() { t.read.Add(-1) }, nil
+}
+
+func (t *testQoSLimiter) WriteRequest(context.Context) (qos.ReleaseFunc, error) {
+	t.write.Add(1)
+	return func() { t.write.Add(-1) }, nil
+}