public async Task GetAttachmentDetails_UnprocessableEntity() { // Arrange int attachmentId = -1; string expectedError = $"Invalid AttachmentId: {attachmentId}"; // Act ActionResult <AttachmentItemModel> response = await _sut.GetAttachmentDetails(attachmentId); // Assert await _mockAttachmentsService.DidNotReceiveWithAnyArgs().RetrieveAsync(default);