✅ GetAttachmentAsync_AsStream_ReturnsStream
✅ GetAttachmentAsync_DifferentContentTypes_ReturnsCorrectData(contentType: "application/pdf", expectedHeader: [37, 80, 68, 70])
✅ GetAttachmentAsync_DifferentContentTypes_ReturnsCorrectData(contentType: "image/jpeg", expectedHeader: [255, 216, 255, 224])
✅ GetAttachmentAsync_DifferentContentTypes_ReturnsCorrectData(contentType: "image/png", expectedHeader: [137, 80, 78, 71])
✅ GetAttachmentAsync_DisposesResponseProperly
✅ GetAttachmentAsync_LargeFile_HandlesCorrectly
✅ GetAttachmentAsync_ReturnsBytes
✅ GetAttachmentAsync_WhenServerReturns400_ThrowsException
✅ GetAttachmentAsync_WhenServerReturnsError_ThrowsException
✅ GetAttachmentAsync_WithCancellationToken_PassesTokenThrough
✅ GetAttachmentAsync_WithInvalidId_ThrowsArgumentException

✅ FullLifecycle_BothHandlersWorkIndependently
✅ HandleAsync_CallsUpdateHandlerWithCorrectParameters
✅ HandleAsync_UpdateHandlerThrowsException_PropagatesException
✅ HandleAsync_ValidParameters_CallsOnlyUpdateHandler
✅ HandleErrorAsync_CallsErrorHandlerWithCorrectParameters
✅ HandleErrorAsync_CancelledToken_CallsErrorHandler
✅ HandleErrorAsync_ErrorHandlerThrowsException_PropagatesException

✅ Add_BooleanValue_BuildsCorrectQuery
✅ Add_EmptyStringValue_Allowed
✅ Add_EnumValue_BuildsCorrectQuery
✅ Add_IntValue_BuildsCorrectQuery
✅ Add_MultipleParameters_BuildsCorrectFormat
✅ Add_NullValue_ThrowsArgumentNullException
✅ Add_NullValueFactory_IgnoresFactory
✅ Add_NullValueFactoryWithStringFallback_Works
✅ Add_NullValueName_ThrowsArgumentNullException
✅ Add_SpecialCharacters_EncodesCorrectly
✅ Add_StringValue_BuildsCorrectQuery
✅ Add_ValueImplementsToString_UsesToString
✅ Add_WithValueFactory_UsesFactoryOutput
✅ AddAndGet_IntValue_ReturnsSameValue
✅ AddAndGet_MultipleCalls_ReturnsEachValue
✅ AddAndGet_NullValue_ThrowsArgumentNullException
✅ AddAndGet_NullValueName_ThrowsArgumentNullException
✅ AddAndGet_StringValue_ReturnsSameValue
✅ AddAndGet_WithValueFactory_UsesFactory
✅ Build_AfterAddAndGet_WorksCorrectly
✅ Build_EmptyRegistry_ReturnsEmptyString
✅ Build_MultipleParameters_MaintainsOrder
✅ Build_SingleParameter_ReturnsCorrectFormat
✅ FullUsageScenario_BuildsCorrectQueryString

✅ AddDeviceAsync_UsesPostMethod
✅ Client_Observables_NotNull
✅ Client_WithAlternativeNumber_StoresCorrectly
✅ Client_WithDifferentBaseUrl_StoresCorrectly
✅ GetAboutAsync_Extension_SendsGetAboutRequest
✅ GetAboutAsync_ReturnsAboutWithAllFields
✅ GetAccountsAsync_ValidRequest_ReturnsAccounts
✅ GetAccountsAsync_WithImmediateTimeout_HandlesGracefully
✅ GetAttachmentAsync_WithUuidAttachmentId_CallsHttpClient
✅ GetAttachmentsAsync_WithEmptyList_ReturnsEmptyCollection
✅ GetDevicesAsync_UsesGetMethod
✅ GetDevicesAsync_WithEmptyList_ReturnsEmptyCollection
✅ GetDevicesAsync_WithMultipleDevices_ReturnsCollection
✅ GetGroupsAsync_ValidRequest_ReturnsGroups
✅ RegisterNumberAsync_WithCaptcha_CallsHttpClient
✅ RegisterNumberAsync_WithoutParameters_CallsHttpClient
✅ RegisterNumberAsync_WithVoiceOption_CallsHttpClient
✅ RemoveAttachmentAsync_UsesDeleteMethod
✅ RemoveAttachmentAsync_WithComplexAttachmentId_CallsHttpClient
✅ SendMessageAsync_Extension_SendsCorrectRequest
✅ SendMessageAsync_MultipleCallsInParallel_AllSucceed
✅ SendMessageAsync_UsesPostMethod
✅ SendMessageAsync_WithAcceptedStatus_Succeeds
✅ SendMessageAsync_WithAlreadyCancelledToken_HandlesGracefully
✅ SendMessageAsync_WithCreatedStatus_Succeeds
✅ SendMessageAsync_WithHttpException_HandlesGracefully
✅ SendMessageAsync_WithNoContentStatus_Succeeds
✅ SendMessageAsync_WithPhoneNumberVariants_CallsHttpClient
✅ SendMessageAsync_WithSpecialCharactersInMessage_CallsHttpClient
✅ SendMessageAsync_WithVeryLongMessage_CallsHttpClient
✅ SetTypingIndicatorAsync_IsTypingFalse_CallsHttpClient
✅ SetTypingIndicatorAsync_WithGroupId_CallsHttpClient
✅ SetTypingIndicatorAsync_WithRecipient_CallsHttpClient
✅ UpdateAccountSettingsAsync_DefaultSettings_CallsHttpClient
✅ UpdateAccountSettingsAsync_DiscoverableFalse_CallsHttpClient
✅ VerifyNumberAsync_ValidToken_ReturnsVerificationResult
✅ VerifyNumberAsync_WithPin_CallsHttpClient

✅ AddDeviceAsync_ValidUri_CallsHttpClient
✅ BaseUrl_ReturnsCorrectValue
✅ GetAboutAsync_ValidRequest_CallsHttpClient
✅ GetAboutAsync_WithCancellationToken_PassesCancellationToken
✅ GetAttachmentsAsync_ValidRequest_CallsHttpClient
✅ GetDevicesAsync_ValidRequest_CallsHttpClient
✅ JsonSerializerOptions_ReturnsNotNull
✅ Number_ReturnsCorrectValue
✅ RemoveAttachmentAsync_ValidAttachmentId_CallsHttpClient
✅ RemovePinAsync_ValidRequest_CallsHttpClient
✅ SendAsync_HttpRequestThrowsException_HandlesGracefully
✅ SendAsync_TaskCanceledException_HandlesGracefully
✅ SendMessageAsync_EmptyMessage_ThrowsArgumentException(message: "   ")
✅ SendMessageAsync_EmptyMessage_ThrowsArgumentException(message: "")
✅ SendMessageAsync_MultipleRecipients_CallsHttpClientOnce
✅ SendMessageAsync_NullMessage_ThrowsArgumentNullException
✅ SendMessageAsync_SingleRecipient_CallsHttpClient
✅ SendMessageAsync_ValidRequest_CallsHttpClient
✅ SendMessageAsync_WithCancellationToken_PassesCancellationToken
✅ SetPinAsync_EmptyPin_StillCallsHttpClient
✅ SetPinAsync_ValidPin_CallsHttpClient
✅ UnregisterDeviceAsync_ValidRequest_CallsHttpClient
✅ UpdateProfileAsync_AllParametersNull_CallsHttpClient
✅ UpdateProfileAsync_WithAbout_CallsHttpClient
✅ UpdateProfileAsync_WithBase64Avatar_CallsHttpClient
✅ UpdateProfileAsync_WithName_CallsHttpClient

✅ Should_Call_Handler_For_Each_Message
✅ Should_Connect_To_WebSocket_Server
✅ Should_Continue_After_Handler_Exception
✅ Should_Dispose_Cleanly
✅ Should_Filter_Multiple_Message_Types_When_All_Ignore_Options_Are_Enabled
✅ Should_Filter_Receipt_Messages_When_IgnoreReceipt_Is_True
✅ Should_Filter_Sync_Messages_When_IgnoreSync_Is_True
✅ Should_Filter_Typing_Messages_When_IgnoreTyping_Is_True
✅ Should_Handle_Exception_In_Handler
✅ Should_Handle_Group_Message
✅ Should_Handle_High_Volume_Sequential_Messages
✅ Should_Handle_Large_Message_Payloads
✅ Should_Handle_Message_With_Attachment
✅ Should_Handle_Message_With_Multiple_Attachments
✅ Should_Handle_Mixed_Message_Types_At_Scale
✅ Should_Handle_Server_Disconnect
✅ Should_Maintain_Message_Order_Under_Load
✅ Should_Not_Filter_Messages_When_All_Ignore_Options_Are_Disabled
✅ Should_Receive_Binary_Message_From_Server
✅ Should_Receive_Multiple_Messages_In_Order
✅ Should_Receive_Text_Message_From_Server
✅ Should_Stop_Processing_After_Cancellation

✅ Constructor_WithNullClient_ThrowsArgumentNullException
✅ Constructor_WithValidClient_CreatesInstance
✅ Dispose_CleansUpResources_Properly
✅ Receiver_ImplementsIAsyncDisposable
✅ StartReceivingAsync_ConfiguresWebSocketUri_Correctly
✅ StartReceivingAsync_WithCancellationToken_RespectsToken
✅ StartReceivingAsync_WithNullHandler_ThrowsArgumentNullException
✅ StartReceivingAsync_WithReceiverOptions_AppliesConfiguration
✅ StartReceivingAsync_WithValidParameters_ReturnsDisposable

✅ Deserialize_WithAllProperties_ShouldSucceed
✅ Deserialize_WithDifferentStatuses_ShouldParseCorrectly(statusString: "TRUSTED_UNVERIFIED", expectedStatus: TrustedUnverified)
✅ Deserialize_WithDifferentStatuses_ShouldParseCorrectly(statusString: "TRUSTED_VERIFIED", expectedStatus: TrustedVerified)
✅ Deserialize_WithDifferentStatuses_ShouldParseCorrectly(statusString: "UNDEFINED", expectedStatus: Undefined)
✅ Deserialize_WithDifferentStatuses_ShouldParseCorrectly(statusString: "UNTRUSTED", expectedStatus: Untrusted)
✅ Deserialize_WithInvalidGuid_ShouldThrowException
✅ Deserialize_WithInvalidStatus_ShouldThrowException
✅ Deserialize_WithNullableProperties_ShouldSucceed
✅ Identity_DefaultValues_ShouldBeNull
✅ RoundTrip_ShouldPreserveData
✅ Serialize_WithAllProperties_ShouldSucceed
✅ Serialize_WithDefaultProperties_ShouldOmitNulls
✅ TestAddDeviceRequestSerializationAndDeserialization
✅ TestAddGroupMemberRequestSerializationAndDeserialization
✅ TestContactSerializationAndDeserialization
✅ TestDeviceSerializationAndDeserialization
✅ TestErrorSerializationAndDeserialization
✅ TestNicknameSerializationAndDeserialization
✅ TestProfileCapabilitiesSerializationAndDeserialization
✅ TestProfileSerializationAndDeserialization
✅ TestRateLimitChallengeRequestSerializationAndDeserialization
✅ TestReceivedMessageSerializationAndDeserialization
✅ TestRegisterNumberRequestSerializationAndDeserialization
✅ TestRemoteDeleteMessageSerializationAndDeserialization
✅ TestRemoveGroupMemberRequestSerializationAndDeserialization
✅ TestSendMessageRequestSerializationAndDeserialization
✅ TestSetConfigurationRequestSerializationAndDeserialization
✅ TestSetTypingIndicatorRequestSerializationAndDeserialization
✅ TestUpdateAccountSettingsRequestSerializationAndDeserialization
✅ TestUpdateContactRequestSerializationAndDeserialization
✅ TestUpdateProfileRequestSerializationAndDeserialization
✅ TestVerifyNumberRequestSerializationAndDeserialization