How to mock a method that returns an int with MOQ

.net, c#, moq

Solution

You cannot mock a static method. You should use some means of dependency injection. Say you make your `GetClientId` method part of an interface called `IUtils` like so:

public interface IUtils
{
    int GetClientId();
}

And you have your concrete class `Utils` implemented as above, but without the method being static (and implementing the interface of course). You now inject an implementation of your interface into the `GetDataClass` class by changing its constructor, like so:

public class GetDataClass
{
     private readonly IUtils utils;

     public GetDataClass(IUtils utils)
     {
         this.utils = utils;
     }

     //SNIP
}

In the `InitRequest` method you change the call `Utils.GetClientID()` to `this.utils.GetClientId()`.

You are now ready to instantiate your `GetDataClass` class with a mock, like so:

var utilsMock = new Mock<IUtils>();
utilsMock.Setup(u => u.GetClientId()).Returns(42);

var getDataClass = new GetDataClass(utilsMock.Object);
getDataClass.InitRequest();

And that's it.

Problem

I have a class that does some retrieving of contents, and it has a method that requires some inputs (filters) before retrieving it. One of the "input" calls another method, which basically returning an int, how do I mock it using MOQ? Here's an example: ``` namespace MyNamespace { public class ConfigMetaDataColumns : MyModel { public int FieldID { get { return ValueInt("FieldID"); } } public int OrderId { get { return ValueInt("OrderId"); } } public string Label { get { return ValueString("Label"); } } public string FieldName { get { return ValueString("FieldName"); } } public int IsReadOnly { get { return ValueInt("IsReadOnly"); } } } public class GetDataClass { protected OpenSQLAccessLayer m_WITObject; // Input Properties public string GroupID; public string PageName; // Output Properties /// <summary> /// Get Config meta data /// </summary> /// <returns></returns> public IEnumerable<ConfigMetaDataColumns> GetConfigMetaData() { var requester = new ListRequester<OpenSQL, ConfigMetaDataColumns>(m_WITObject, "Result[0].RowCount", "Result[0].Row[{0}]."); return requester.Items; } public void InitRequest() { User user = (User)HttpContext.Current.User; m_WITObject = user.NewService<OpenSQLAccessLayer>(); m_WITObject.SetInput("MultipleResultSets", 1); m_WITObject.SetInput("ClientID", Utils.GetClientID()); m_WITObject.SetInput("GroupID", GroupID); m_WITObject.SetInput("PageName", PageName); m_WITObject.Retrieve(); } } } ``` This is the "GetClientID()" method: ``` public static int GetClientID() { User oUser = (User)HttpContext.Current.User; int nClientID; string sClientID = string.Empty; if (String.IsNullOrEmpty(oUser.Session("clientid"))) { Client oClient = new Client(); } oUser = (User)HttpContext.Current.User; sClientID = oUser.Session("clientid"); //If we couldn't retrieve it, throw exception if ( string.IsNullOrEmpty(sClientID) || !int.TryParse(sClientID, out nClientID)) { throw new Exception("No clientid found in user session, client not authenticated, please login from main page"); } return nClientID; } ``` I'm just looking for a way for me to pass in a hard-coded value for the ClientID, and use this to do some unit testing with the GetDataClass class. Thanks.

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