how to perform mocking in xunit testing project

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C#

ASP.NET5

I have created a ASP.net vnext class library project in Visual Studio 2015. Now I want to test my project.I am using Xunit for testing. So, I want to use mocking stuffs in my test project. Here is my project.json file

{
    "version": "1.0.0-*",
    "dependencies": {
        "xunit": "2.0.0-rc3-build2880",
        "xunit.runner.aspnet": "2.0.0-rc3-build52",
          "My project name with version",
           "Moq": "4.2.1502.911"     
    },
 
    "commands": { "test": "xunit.runner.aspnet" },
 
    "frameworks": {
        "aspnet50": {
            "dependencies": {             
 
            }
        }
 
    }
    }

But I am getting error :Dependency Moq with the Version 4.2.1502.911 could not be resolved.

I also tried different version of Moq, but results the same: dependency error.
Without Mock I can't move further in testing.

Any help?