如何对该方法进行单元测试

Question

I'm learning unit testing. How would the following method be unit tested on VS 2010?

private string[] lstStrCalculatePoints()
{
    string[] lstStrPoints = new string[2];
    if (lblKPIAResult.Text.Contains("Exceeds"))
    {
       lstStrPoints[0] = "AHT";
    }

    if (lblKPIBResult.Text.Contains("Exceeds"))
    {
        lstStrPoints[1] = "QA";
    }

    return lstStrPoints;
}

Please provide example. Thanks!

Answer 1

I'd create two new methods:

public static string GetKpiPoint(string kpiResult, string ifExceeds)
{
    return kpiResult.Contains("Exceeds") ? ifExceeds : null;
}

public static string[] CalculatePoints(string kpiAResult, string kpiBResult)
{
    return new string[] { GetKpiPoint(kpiAResult, "AHT"), GetKpiPoint(kpiBResult, "QA") };
}

then call it from your exising one:

private string[] lstStrCalculatePoints()
{
    return CalcualtePoints(lblKPIAResult.Text, lblKPIBResult.Text);
}

EDIT: The ways you can test this method depend on your test framework, but if you're using NUnit you can do something like:

[Test]
[TestCase("Exceeds", "Exceeds", new string[] { "AHT", "QA" })]
[TestCase("NoMatch", "NoMatch", new string[] { null, null })]
[TestCase("Exceeds", "NoMatch", new string[] { "AHT", null })]
[TestCase("NoMatch", "Exceeds", new string[] { null, "QA" })]
public void CalculatePointsTest(string kpiA, string kpiB, string[] expected)
{
    CollectionAssert.AreEqual(expected, CalculatePoints(kpiA, kpiB));
}

Answer 2

I would not test private methods directly.

You test them indirectly by testing public methods that invoke private methods. This is to prevent you from breaking encapsulation, and it will allow you to refactor your code without having to update your tests unnecessarily.

So long as the public interface works as defined, I do not care what the class does behind the scenes so long as I fully test the public interface's specification.

PS: protected methods are a different story however, but beyond the scope of the question.

Answer 3

From the lblKPI<n>Result attributes I guess you're in a WinForm application, right? You will be better off separating your presentation logic from your view (the Form where lstStrCalculatePoints lives) and put it in a Presenter (or similar). Read up on eg. Model-View-Presenter (MVP) or another MVC deriviate pattern. Do your unit testing on the Presenter class.