Mocking System.Collections.Generic.IList with Moq

Question

I am struggeling with writing unit tests for my class AttachmentProcessor. My goal is to test all methods and mock for example IList FileList.

 public class AttachmentsProcessor { public IList<IFileInfo> FileList { get; set; } public AttachmentsProcessor(IList<IFileInfo> FileList) { ... } public void RemoveAttachment(int index) { ... } public long GetTotalFilesSize() { ... } public void GetFilesFromDialog(IOpenFileDialog2 openFileDialog1) { ... } }

Interface :

public interface IFileProcessor { IList<IFileInfo> FileList { get; set; } void RemoveAttachment(int index); long GetTotalFilesSize(); void GetFilesFromDialog(IOpenFileDialog2 openFileDialog1); }

Why are you unit testing that in the first place? You're just wrapping a list for convience methods, you don't even need that method in the first place, Secondly AttachmentsInfo may be a IFileInfo, but not vice versa so if you want to act upon it like so your initial call must be AttachmentsProcessor<IFileInfo> but if you're going to do that you should use a structure better suited to handle co-variance and contravariance — johnny 5
– johnny 5, Commented Mar 21, 2017 at 15:37
Quick question - what is benefit of using AttachmentProcessor over using simple List<AttahcmentsInfo>? — Sergey Berezovskiy
– Sergey Berezovskiy, Commented Mar 21, 2017 at 15:57
@SergeyBerezovskiy I have methods like GetSizeOfAllAttachments, GetFilesFromDialog, or GetFilesFromDragandDrop Event etc. — Ngine
– Ngine, Commented Mar 22, 2017 at 8:29
@johnny5 thank you for your reply ...it makes sense. But I still don't know how to mock a List<AttachmentInfo>. I just want to moq the AttachmentInfo objects in that list. — Ngine
– Ngine, Commented Mar 22, 2017 at 8:30
I don't understand what you're trying to do. Post a function you're trying to moq. You are aware that you don't have to moq everything sometimes you just need to make. Fake dto — johnny 5
– johnny 5, Commented Mar 22, 2017 at 12:47

Ngine · Accepted Answer · 2017-03-22 13:34:02Z

I've solved my problem. My problem was that I did not know how to make mocks for my Class AttachmentProcessor:IFileProcessor and List. I ended up with this solution and it worked ! Thanks for all replies.

 var mockFileProcessor = new Mock<IFileProcessor>(); //here is how I mocked my AttachmentProcessor var mockAttachmentInfo = new Mock<IFileInfo>(); ///here is how I mocked my AttachmentInfo mockAttachmentInfo.Setup(m => m.Length).Returns(() => 200); mockFileProcessor.Setup(m => m.FileList).Returns(() => new List<IFileInfo> { mockAttachmentInfo.Object, mockAttachmentInfo.Object, mockAttachmentInfo.Object, mockAttachmentInfo.Object, mockAttachmentInfo.Object }); /// and this is the part where I mocked my IList<AttachmentInfo>

I ended up with this solution and it worked ! Thanks for all replies

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Mocking System.Collections.Generic.IList with Moq

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