Skip to main content

Can we mock an extension method?

Pentru teste mai mult ca sigur ati folosit un framework petru a face mock pe diferite obiecte. In general am folosit Moq pentru a putea face mock la date. Este destul de usor de folosit, mai jos puteti sa gasiti un exemplu:
Mock<IService> serviceMock = new Mock<IService>();
serviceMock
    .Setup(x=>x.Call(It.IsAny<string>))
    .Returns(()=> new Result());
Mai sus am creat un mock pentru IService, iar in momentul in care se apeleaza metoda Call cu orice parametru de tip string, se returneaza un nou obiect de tip Result.
Nimic deosebit pana acuma. Dar ce se intampla daca vrem sa facem mock la un extension method. Vestea proasta este ca nu se poate face. Majoritatea framework-urilor pentru mock-ing nu suporta aceasta functionalitate.
Cea mai buna solutie este sa refactorizam codul daca putem. Dar exista cazuri cand acest lucru nu il putem face sau extension method nu este declarat de noi si vine dintr-un assembly exterior.
O solutie comuna, care poate sa fie folosita atat pentru aplicatiile .NET classic, Silverlight, WP7, ... este sa injectam actiunea care apeleaza metoda noastra. De exemplu putem sa extragem intr-un Action actiunea care apeleaza extension method, iar aceasta sa fie injectata prin contructor folosind un factory de exemplu. O alta varianta este sa facem un wrapper peste clasa noastra.
Urmatoarea solutie nu functioneaza pe Silverlight din pacate. Ar fi fost nice sa fie suportatat macar in versiunea 5, dar nici o sansa. Solutie se refera la folosirea Microsoft Moles. Prin intermediul acestui framework putem sa inlocuim orice clasa, metoda cu un mole care sa faca ce vrem noi. Un mole, intercepteaza apelul spre o anumita metoda si se poate executa orice alt cod. Putem sa facem mole la orice fel de metoda, atat statica cat si extension method.

Comments

  1. Un extension method nu e decat o metoda statica, deci nu e de mirare ca majoritatea frameworkurilor de mocking care lucreaza cu metode "ortodoxe" nu au cum sa creeze un mock pentru asa ceva..

    Si Moles sau Typemock Isolator pot sa mockuiasca o metoda statica pentru ca se baga cu CLR profiler-ul si rescriu IL-ul, si alte ghidusii de genul.

    ReplyDelete
  2. Partea interesanta este cand ai un proiect Silverlight si nu ai aceste optiuni.
    Daca ar fi sa aleg intre Moles si Moq as alege Moq, dar uneori nu ai de ales, sau in cazul asta numarul de optiuni este egal cu 0.

    ReplyDelete
  3. Da, in cazul acesta daca mocking framework-ul nu are versiune de Silverlight, cam singura optiune e un adapter sau refactoring daca e posibil..

    ReplyDelete
  4. Am ajuns la o solutie asemanatoare. Putin de refactoring, un factory impreuna cu un adaptor. O sa revin maine cu implementarea exacta.

    ReplyDelete

Post a Comment

Popular posts from this blog

Windows Docker Containers can make WIN32 API calls, use COM and ASP.NET WebForms

After the last post , I received two interesting questions related to Docker and Windows. People were interested if we do Win32 API calls from a Docker container and if there is support for COM. WIN32 Support To test calls to WIN32 API, let’s try to populate SYSTEM_INFO class. [StructLayout(LayoutKind.Sequential)] public struct SYSTEM_INFO { public uint dwOemId; public uint dwPageSize; public uint lpMinimumApplicationAddress; public uint lpMaximumApplicationAddress; public uint dwActiveProcessorMask; public uint dwNumberOfProcessors; public uint dwProcessorType; public uint dwAllocationGranularity; public uint dwProcessorLevel; public uint dwProcessorRevision; } ... [DllImport("kernel32")] static extern void GetSystemInfo(ref SYSTEM_INFO pSI); ... SYSTEM_INFO pSI = new SYSTEM_INFO(

Azure AD and AWS Cognito side-by-side

In the last few weeks, I was involved in multiple opportunities on Microsoft Azure and Amazon, where we had to analyse AWS Cognito, Azure AD and other solutions that are available on the market. I decided to consolidate in one post all features and differences that I identified for both of them that we should need to take into account. Take into account that Azure AD is an identity and access management services well integrated with Microsoft stack. In comparison, AWS Cognito is just a user sign-up, sign-in and access control and nothing more. The focus is not on the main features, is more on small things that can make a difference when you want to decide where we want to store and manage our users.  This information might be useful in the future when we need to decide where we want to keep and manage our users.  Feature Azure AD (B2C, B2C) AWS Cognito Access token lifetime Default 1h – the value is configurable 1h – cannot be modified

What to do when you hit the throughput limits of Azure Storage (Blobs)

In this post we will talk about how we can detect when we hit a throughput limit of Azure Storage and what we can do in that moment. Context If we take a look on Scalability Targets of Azure Storage ( https://azure.microsoft.com/en-us/documentation/articles/storage-scalability-targets/ ) we will observe that the limits are prety high. But, based on our business logic we can end up at this limits. If you create a system that is hitted by a high number of device, you can hit easily the total number of requests rate that can be done on a Storage Account. This limits on Azure is 20.000 IOPS (entities or messages per second) where (and this is very important) the size of the request is 1KB. Normally, if you make a load tests where 20.000 clients will hit different blobs storages from the same Azure Storage Account, this limits can be reached. How we can detect this problem? From client, we can detect that this limits was reached based on the HTTP error code that is returned by HTTP