diff --git a/ydb/core/testlib/test_client.cpp b/ydb/core/testlib/test_client.cpp
index 6ef5ad171ce5..1100e4faa118 100644
--- a/ydb/core/testlib/test_client.cpp
+++ b/ydb/core/testlib/test_client.cpp
@@ -245,6 +245,8 @@ namespace Tests {
             appData.DataStreamsAuthFactory = Settings->DataStreamsAuthFactory.get();
             appData.PersQueueMirrorReaderFactory = Settings->PersQueueMirrorReaderFactory.get();
             appData.HiveConfig.MergeFrom(Settings->AppConfig->GetHiveConfig());
+            const auto& hostnamePatterns = Settings->AppConfig->GetQueryServiceConfig().GetHostnamePatterns();
+            appData.ExternalSourceFactory = NExternalSource::CreateExternalSourceFactory(std::vector<TString>(hostnamePatterns.begin(), hostnamePatterns.end()));
 
             appData.DynamicNameserviceConfig = new TDynamicNameserviceConfig;
             auto dnConfig = appData.DynamicNameserviceConfig;