[#334] engine: Make tests more predictable

There is a codecov issue because objects are not placed
in the engine the same way every unit test. Therefore
sometimes there are more coverage, sometimes there are
less. Seeded RNG should solve this issue for engine tests.

Signed-off-by: Alex Vanin <alexey@nspcc.ru>

pkg/local_object_storage/blobovnicza/blobovnicza_test.go

@@ -1,8 +1,8 @@
 package blobovnicza
 
 import (
-	"crypto/rand"
 	"crypto/sha256"
+	"math/rand"
 	"os"
 	"testing"
 
@@ -70,6 +70,8 @@ func testGet(t *testing.T, blz *Blobovnicza, addr *objectSDK.Address, expObj []b
 }
 
 func TestBlobovnicza(t *testing.T) {
+	rand.Seed(1024)
+
 	p := "./test_blz"
 
 	sizeLim := uint64(256 * 1 << 10) // 256KB

pkg/local_object_storage/blobstor/blobovnicza_test.go

@@ -1,9 +1,9 @@
 package blobstor
 
 import (
-	"crypto/rand"
 	"crypto/sha256"
 	"errors"
+	"math/rand"
 	"os"
 	"testing"
 
@@ -55,6 +55,8 @@ func testObject(sz uint64) *object.Object {
 }
 
 func TestBlobovniczas(t *testing.T) {
+	rand.Seed(1024)
+
 	l := test.NewLogger(false)
 	p := "./test_blz"
 

pkg/local_object_storage/metabase/db_test.go

@@ -1,8 +1,8 @@
 package meta_test
 
 import (
-	"crypto/rand"
 	"crypto/sha256"
+	"math/rand"
 	"os"
 	"testing"
 

pkg/local_object_storage/shard/shard_test.go

@@ -1,8 +1,8 @@
 package shard_test
 
 import (
-	"crypto/rand"
 	"crypto/sha256"
+	"math/rand"
 	"os"
 	"path"
 	"testing"