How can I stop a data-driven coded ui test

Question 1

I had similar issue and after some research I found that there are two possible solution: 1. The complicated one - create your own Test Dispatcher with your own custom data adapter by implementing ITestMethodInvoker interface. There you can run test iteration in the way you wish. You will also need to override TestContex class to feed your Test Method with DataRows from your data adapter. 2. The simplest one - this wont actually stop Visual Studio from iterating through all DataRows in your Data Source but instead of performing the actual test method, Visual Studio will mark it as skipped and move on. Here is the sample code:

[CodedUITest]
public class MyTestClass
{
    private TestContext testContext;
    private static int countFailedIterations = 0;
    private static string currentMethod = "";

    public MyTestClass()
    {
        if (!currentMethod.Equals(testContext.FullyQualifiedTestClassName))
        {
            // Reset Iteration Count
            countFailedIterations = 0;
            currentMethod = testContext.FullyQualifiedTestClassName;
        }
    }

    [TestInitialize]
    public void MyTestInit()
    {
        if (countFailedIterations > 0)
            Assert.Inconclusive("Stop it, please");
    }

    [TestCleanup]
    public void MytestCleanup()
    {
        if (testContext.CurrentTestOutcome != UnitTestOutcome.Passed)
            countFailedIterations++;
    }

    [TestMethod]
    [DataSource("MyDataSource")]
    public void MyTestMethod()
    {
        //Blah Blah Blah
    }

    public TestContext TestContext
    {
        get { return testContext; }
        set { testContext = value; }
    }
}

Question 2

The code inside constructor is required only if you have multiple data-driven test methods so you would like to reset failed iterations counter. But you're right - when the constructor runs the TestContext is still not initialized. You can actually move the code from the constructor to MyTestInit() method - it should work.