gistfile1.cs

[TestClass]
class Tests {
    [TestMethod]
    public void DataSet_A() {
        RunTestWithData("A", "Z");
    }

    [TestMethod]
    public void DataSet_B() {
        RunTestWithData("B", "Y");
    }

    private void RunTestWithData(string arg1, string arg2) {
        var api = new API();
        var result = api.Foo(arg1, arg2);

        Assert.IsTrue(result, "Called with " + arg1 + ", " + arg2);
    }
}