public void AddPackages_Adds_New_Depedenency()
        {
            string initialJson  = @"{
  ""dependencies"": {
    ""Newtonsoft.Json"": ""5.0.8"",
    ""Microsoft.Net.Runtime.Interfaces"": """"
    }
}";
            string expectedJson = @"{
  ""dependencies"": {
    ""Newtonsoft.Json"": ""5.0.8"",
    ""Microsoft.Net.Runtime.Interfaces"": """",
    ""Microsoft.Net.Runtime"": ""1.0.0""
  }
}";

            _mockFileSystem.WriteAllText(_projectJsonPath, initialJson);

            _packageInstaller.AddPackages(new[] { new PackageMetadata()
                                                  {
                                                      Name    = "Microsoft.Net.Runtime",
                                                      Version = "1.0.0"
                                                  } });

            var actualJson = _mockFileSystem.ReadAllText(_projectJsonPath);

            Assert.Equal(expectedJson, actualJson);
        }