diff --git a/ydb/core/testlib/actors/block_events.h b/ydb/core/testlib/actors/block_events.h
index 2b76acf54eca..a267d4f3cc33 100644
--- a/ydb/core/testlib/actors/block_events.h
+++ b/ydb/core/testlib/actors/block_events.h
@@ -27,7 +27,7 @@ namespace NActors {
          * Unblocks up to count events at the front of the deque, allowing them
          * to be handled by the destination actor.
          */
-        TBlockEvents& Unblock(size_t count = -1) {
+        TBlockEvents& Unblock(size_t count = Max<size_t>()) {
             while (!this->empty() && count > 0) {
                 auto& ev = this->front();
                 if (!Stopped) {
@@ -36,6 +36,7 @@ namespace NActors {
                 }
                 ui32 nodeId = ev->GetRecipientRewrite().NodeId();
                 ui32 nodeIdx = nodeId - Runtime.GetFirstNodeId();
+                Cerr << "TBlockEvents::Unblock " << typeid(TEvType).name() << " from " << Runtime.FindActorName(ev->Sender) << " to " << Runtime.FindActorName(ev->GetRecipientRewrite()) << Endl;
                 Runtime.Send(ev.Release(), nodeIdx, /* viaActorSystem */ true);
                 this->pop_front();
                 --count;
@@ -67,6 +68,7 @@ namespace NActors {
                 return;
             }
 
+            Cerr << "TBlockEvents::Block " << typeid(TEvType).name() << " from " << Runtime.FindActorName(ev->Sender) << " to " << Runtime.FindActorName(ev->GetRecipientRewrite()) << Endl;
             this->emplace_back(std::move(ev));
         }
 
diff --git a/ydb/core/tx/datashard/datashard_ut_build_index.cpp b/ydb/core/tx/datashard/datashard_ut_build_index.cpp
index 35cb7139e6d6..243721d8a2d2 100644
--- a/ydb/core/tx/datashard/datashard_ut_build_index.cpp
+++ b/ydb/core/tx/datashard/datashard_ut_build_index.cpp
@@ -6,6 +6,7 @@
 #include <ydb/core/tx/schemeshard/schemeshard.h>
 #include <ydb/core/tx/tx_proxy/proxy.h>
 #include <ydb/core/tx/tx_proxy/upload_rows.h>
+#include <ydb/core/testlib/actors/block_events.h>
 
 #include <ydb/library/yql/public/issue/yql_issue_message.h>
 
@@ -167,11 +168,8 @@ Y_UNIT_TEST_SUITE(TTxDataShardBuildIndexScan) {
 
         CreateShardedTableForIndex(server, sender, "/Root", "table-2", 1, false);
 
-        auto observer = runtime.AddObserver<TEvDataShard::TEvCompactBorrowed>([&](TEvDataShard::TEvCompactBorrowed::TPtr& event) {
-            Cerr << "Captured TEvDataShard::TEvCompactBorrowed from " << runtime.FindActorName(event->Sender) << " to " << runtime.FindActorName(event->GetRecipientRewrite()) << Endl;
-            if (runtime.FindActorName(event->Sender) == "FLAT_SCHEMESHARD_ACTOR") {
-                event.Reset();
-            }
+        TBlockEvents<TEvDataShard::TEvCompactBorrowed> block(runtime, [&](TEvDataShard::TEvCompactBorrowed::TPtr& event) {
+            return runtime.FindActorName(event->Sender) == "FLAT_SCHEMESHARD_ACTOR";
         });
 
         auto snapshot = CreateVolatileSnapshot(server, { "/Root/table-1" });
diff --git a/ydb/core/tx/datashard/datashard_ut_stats.cpp b/ydb/core/tx/datashard/datashard_ut_stats.cpp
index 50f64b8c231c..e5b17cef8c69 100644
--- a/ydb/core/tx/datashard/datashard_ut_stats.cpp
+++ b/ydb/core/tx/datashard/datashard_ut_stats.cpp
@@ -1,6 +1,7 @@
 #include <ydb/core/tx/datashard/ut_common/datashard_ut_common.h>
 #include <ydb/core/tablet_flat/shared_sausagecache.h>
 #include <ydb/core/tablet_flat/test/libs/table/test_make.h>
+#include <ydb/core/testlib/actors/block_events.h>
 
 namespace NKikimr {
 
@@ -441,28 +442,16 @@ Y_UNIT_TEST_SUITE(DataShardStats) {
         const auto shard1 = GetTableShards(server, sender, "/Root/table-1").at(0);
 
         UpsertRows(server, sender);
-        
-        bool captured = false;
-        auto observer = runtime.AddObserver<NSharedCache::TEvResult>([&](NSharedCache::TEvResult::TPtr& event) {
-            Cerr << "Captured NSharedCache::TEvResult from " << runtime.FindActorName(event->Sender) << " to " << runtime.FindActorName(event->GetRecipientRewrite()) << Endl;
-            if (runtime.FindActorName(event->GetRecipientRewrite()) == "DATASHARD_STATS_BUILDER") {
-                auto& message = *event->Get();
-                event.Reset(static_cast<TEventHandle<NSharedCache::TEvResult> *>(
-                    new IEventHandle(event->Recipient, event->Sender, 
-                        new NSharedCache::TEvResult(message.Origin, message.Cookie, NKikimrProto::NODATA))));
-                captured = true;
-            }
+
+        TBlockEvents<NSharedCache::TEvResult> block(runtime, [&](NSharedCache::TEvResult::TPtr& event) {
+            return runtime.FindActorName(event->GetRecipientRewrite()) == "DATASHARD_STATS_BUILDER";
         });
 
         CompactTable(runtime, shard1, tableId1, false);
 
-        for (int i = 0; i < 5 && !captured; ++i) {
-            TDispatchOptions options;
-            options.CustomFinalCondition = [&]() { return captured; };
-            runtime.DispatchEvents(options, TDuration::Seconds(5));
-        }
-        UNIT_ASSERT(captured);
-        observer.Remove();
+        runtime.WaitFor("blocked read", [&]{ return block.size(); });
+
+        block.Stop().Unblock();
 
         {
             Cerr << "Waiting stats.." << Endl;