MSTest で TestCaseSource を型付きで書く ref: http://qiita.com/wipiano/items/a5a47811a85bbbf382cc

Add.cs

public static int Add(int x, int y)
{
    return x + y;
}

SampleTest.cs

[TestClass]
public class SampleTest
{
    public TestContext TestContext { get; set; }        

    [TestCaseSource(nameof(AddTestCaseSource))]
    [TestMethod]
    public void AddTest()
    {
        TestContext.Run((int x, int y, int expected) =>
        {
            Add(x, y).Is(expected);
        });
    }

    // テストケース
    private static readonly object[][] AddTestCaseSource = new object[][]
    {
        // object の配列。。
        new object[] {1, 2, 3},
        new object[] {4, 4, 8},
        new object[] {-1, -1, -2},
        new object[] {0, 0, 0},
        // ...
    };
}

SampleTest2.cs

[TestClass]
public class SampleTest
{
    public TestContext TestContext { get; set; }        

    [TestCaseSource(nameof(AddTestCaseSource))]
    [TestMethod]
    public void AddTest()
    {
        TestContext.Run((AddTestCase testCase) =>
        {
            Add(testCase.X, testCase.Y).Is(testCase.Expected);
        });
    }


    private static readonly object[][] AddTestCaseSource = new object[][]
    {
        new object[] {new AddTestCase() {X = 1, Y = 2, Expected = 3}},
        new object[] {new AddTestCase() {X = 4, Y = 4, Expected = 8}},
        new object[] {new AddTestCase() {X = -1, Y = -1, Expected = -2}}, 
        new object[] {new AddTestCase() {X = 0, Y = 0, Expected = 0}}, 
        // ...
    };
}

SampleTest3.cs

[TestClass]
public class SampleTest
{
    public TestContext TestContext { get; set; }        

    [TestCaseSource(nameof(AddTestCaseSource))]
    [TestMethod]
    public void AddTest()
    {
        TestContext.Run((AddTestCase testCase) =>
        {
            Add(testCase.X, testCase.Y).Is(testCase.Expected);
        });
    }


    private static readonly object[][] AddTestCaseSource = new object[][]
    {
        new AddTestCase() {X = 1, Y = 2, Expected = 3},
        new AddTestCase() {X = 4, Y = 4, Expected = 8},
        new AddTestCase() {X = -1, Y = -1, Expected = -2}, 
        new AddTestCase() {X = 0, Y = 0, Expected = 0}, 
        // ...
    };
}

TestCaseObject1.cs

internal class AddTestCase
{
    public int X { get; set; }
    public int Y { get; set; }
    public int Expected { get; set; }
}

TestCaseObject2.cs

internal class AddTestCase
{
    public int X { get; set; }
    public int Y { get; set; }
    public int Expected { get; set; }

    public static implicit operator object[](AddTestCase testCase)
        => new object[] {testCase};
}