diff --git a/WotBlitzStatisticsPro.Blazor.Tests/Services/GraphQlBackendServiceTests.cs b/WotBlitzStatisticsPro.Blazor.Tests/Services/GraphQlBackendServiceTests.cs
new file mode 100644
index 0000000..ffe90bf
--- /dev/null
+++ b/WotBlitzStatisticsPro.Blazor.Tests/Services/GraphQlBackendServiceTests.cs
@@ -0,0 +1,156 @@
+using System.Collections.Generic;
+using System.Threading;
+using System.Threading.Tasks;
+using FluentAssertions;
+using Moq;
+using NUnit.Framework;
+using StrawberryShake;
+using WotBlitzStatisticsPro.Blazor.GraphQl;
+using WotBlitzStatisticsPro.Blazor.Services;
+
+namespace WotBlitzStatisticsPro.Blazor.Tests.Services
+{
+    public class GraphQlBackendServiceTests
+    {
+        private Mock<IFindClansQuery> _findClanQueryMock;
+        private Mock<IFindPlayersQuery> _findPlayersQueryMock;
+        private WotBlitzStatisticsProClient _generatedClient;
+        private Mock<INotificationsService> _notificationServiceMock;
+        private GraphQlBackendService _service;
+
+        private readonly GraphQlBackendMockService _mockDataService = new(false);
+
+        private Mock<IFindPlayersResult> _findPlayersResultMock;
+        private List<IClientError> _findPlayersErrors;
+        private Mock<IOperationResult<IFindPlayersResult>> _findPlayersOperationResultMock;
+
+        private Mock<IFindClansResult> _findClansResultMock;
+        private List<IClientError> _findClansErrors;
+        private Mock<IOperationResult<IFindClansResult>> _findClansOperationResultMock;
+
+        [SetUp]
+        public async Task Init()
+        {
+            _findClanQueryMock = new();
+            _findPlayersQueryMock = new();
+
+            await SetUpFindClans();
+            await SetUpFindPlayers();
+
+            _generatedClient =
+                new WotBlitzStatisticsProClient(_findClanQueryMock.Object, _findPlayersQueryMock.Object);
+
+            _notificationServiceMock = new();
+
+            _service = new GraphQlBackendService(_generatedClient, _notificationServiceMock.Object);
+        }
+
+        [Test]
+        public async Task ShouldCallFindPlayers()
+        {
+            string expectedSearch = "Foo";
+            var expectedRealm = RealmType.Ru;
+            _findPlayersOperationResultMock.SetupGet(r => r.Data).Returns(_findPlayersResultMock.Object);
+
+            var players = await _service.FindPlayers(expectedSearch, expectedRealm);
+
+            players.Should().NotBeNull();
+            players.Should().NotBeEmpty();
+            _findPlayersQueryMock.Verify(q => q.ExecuteAsync(expectedSearch, expectedRealm, It.IsAny<RequestLanguage>(), It.IsAny<CancellationToken>()), Times.Once);
+            _notificationServiceMock.Verify(n => n.ReportError(It.IsAny<string>(), It.IsAny<string>()), Times.Never);
+        }
+
+        [Test]
+        public async Task ShouldNotifyAboutErrorIfFindPlayersFails()
+        {
+            string expectedSearch = "Foo";
+            var expectedRealm = RealmType.Ru;
+
+            AddErrorToResult();
+
+            var players = await _service.FindPlayers(expectedSearch, expectedRealm);
+
+            players.Should().BeNull();
+            _findPlayersQueryMock.Verify(q => q.ExecuteAsync(expectedSearch, expectedRealm, It.IsAny<RequestLanguage>(), It.IsAny<CancellationToken>()), Times.Once);
+            _notificationServiceMock.Verify(n => n.ReportError(It.IsAny<string>(), It.IsAny<string>()), Times.Once);
+        }
+
+
+        [Test]
+        public async Task ShouldCallFindClans()
+        {
+            string expectedSearch = "Foo";
+            var expectedRealm = RealmType.Ru;
+            _findClansOperationResultMock.SetupGet(r => r.Data).Returns(_findClansResultMock.Object);
+
+            var clans = await _service.FindClans(expectedSearch, expectedRealm);
+
+            clans.Should().NotBeNull();
+            clans.Should().NotBeEmpty();
+            _findClanQueryMock.Verify(q => q.ExecuteAsync(expectedSearch, expectedRealm, It.IsAny<RequestLanguage>(), It.IsAny<CancellationToken>()), Times.Once);
+            _notificationServiceMock.Verify(n => n.ReportError(It.IsAny<string>(), It.IsAny<string>()), Times.Never);
+
+        }
+
+        [Test]
+        public async Task ShouldNotifyAboutErrorIfFindClansFails()
+        {
+            string expectedSearch = "Foo";
+            var expectedRealm = RealmType.Ru;
+
+            AddErrorToResult();
+
+            var players = await _service.FindClans(expectedSearch, expectedRealm);
+
+            players.Should().BeNull();
+            _findClanQueryMock.Verify(q => q.ExecuteAsync(expectedSearch, expectedRealm, It.IsAny<RequestLanguage>(), It.IsAny<CancellationToken>()), Times.Once);
+            _notificationServiceMock.Verify(n => n.ReportError(It.IsAny<string>(), It.IsAny<string>()), Times.Once);
+        }
+
+        private async Task SetUpFindPlayers()
+        {
+            var players = await _mockDataService.FindPlayers("foo", RealmType.Ru);
+
+            _findPlayersErrors = new List<IClientError>();
+            _findPlayersResultMock = new();
+            _findPlayersOperationResultMock = new();
+            _findPlayersResultMock.SetupGet(r => r.Players).Returns(players);
+            _findPlayersOperationResultMock.SetupGet(r => r.Errors).Returns(_findPlayersErrors);
+
+            _findPlayersQueryMock.Setup(q => q.ExecuteAsync(
+                    It.IsAny<string>(),
+                    It.IsAny<RealmType>(),
+                    It.IsAny<RequestLanguage>(),
+                    It.IsAny<CancellationToken>()))
+                .ReturnsAsync(_findPlayersOperationResultMock.Object);
+        }
+
+        private async Task SetUpFindClans()
+        {
+            var clans = await _mockDataService.FindClans("foo", RealmType.Ru);
+
+            _findClansErrors = new List<IClientError>();
+            _findClansResultMock = new();
+            _findClansOperationResultMock = new();
+            _findClansResultMock.SetupGet(r => r.Clans).Returns(clans);
+            _findClansOperationResultMock.SetupGet(r => r.Errors).Returns(_findClansErrors);
+
+            _findClanQueryMock.Setup(q => q.ExecuteAsync(
+                    It.IsAny<string>(),
+                    It.IsAny<RealmType>(),
+                    It.IsAny<RequestLanguage>(),
+                    It.IsAny<CancellationToken>()))
+                .ReturnsAsync(_findClansOperationResultMock.Object);
+        }
+
+        private void AddErrorToResult()
+        {
+            string graphQlErrorMessage = "{\"errors\": [{\"extensions\": {\"message\": \"GraphQL error message here\"}}]}";
+            var errorDetails = new Dictionary<string, object?> {["error"] = graphQlErrorMessage};
+            var error = new Mock<IClientError>();
+            error.SetupGet(e => e.Extensions).Returns(errorDetails);
+            _findPlayersErrors.Add(error.Object);
+            _findClansErrors.Add(error.Object);
+        }
+    }
+}
\ No newline at end of file
diff --git a/WotBlitzStatisticsPro.Blazor/Services/GraphQlBackendMockService.cs b/WotBlitzStatisticsPro.Blazor/Services/GraphQlBackendMockService.cs
index d714548..65822bd 100644
--- a/WotBlitzStatisticsPro.Blazor/Services/GraphQlBackendMockService.cs
+++ b/WotBlitzStatisticsPro.Blazor/Services/GraphQlBackendMockService.cs
@@ -10,6 +10,18 @@ namespace WotBlitzStatisticsPro.Blazor.Services
 {
     public class GraphQlBackendMockService: IGraphQlBackendService
     {
+        private readonly bool _needToWait;
+
+        public GraphQlBackendMockService()
+        {
+            _needToWait = true;
+        }
+
+        public GraphQlBackendMockService(bool needToWait)
+        {
+            _needToWait = needToWait;
+        }
+
         public async Task<IReadOnlyList<IFindPlayers_Players>?> FindPlayers(string accountNick, RealmType realmType)
         {
             var result = new List<IFindPlayers_Players>();
@@ -28,7 +40,10 @@ namespace WotBlitzStatisticsPro.Blazor.Services
                     faker.Random.Number(30, 90)));
             }
 
-            await Task.Delay(1000);
+            if (_needToWait)
+            {
+                await Task.Delay(1000);
+            }
 
             return result;
         }
@@ -51,7 +66,10 @@ namespace WotBlitzStatisticsPro.Blazor.Services
             }
 
 
-            await Task.Delay(1000);
+            if (_needToWait)
+            {
+                await Task.Delay(1000);
+            }
 
             return result;
         }