Write NUnit Test case for a method which prompts a message box

c#, nunit-2.5

Solution

You have to inject something that will stub the `Show User Dialog` call. Then you can within your test set the stub to the desired user answer and call your method:

public class MyClass
{
    private IMessageBox _MessageBox;

    public MyClass(IMessageBox messageBox)
    {
        _MessageBox = messageBox;
    }

    public bool MyMethod(string arg)
    {
        var result = _MessageBox.ShowDialog();
        return result == DialogResult.Ok;
    }
}

internal class MessageBoxStub : IMessageBox
{
    DialogResult Result {get;set;}

    public DialogResult ShowDialog()
    {
        return Result;
    }
}

[Test]
public void MyTest()
{
    var messageBox = new MessageBoxStub() { Result = DialogResult.Yes }
    var unitUnderTest = new MyClass(messageBox);

    Assert.That(unitUnderTest.MyMethod(null), Is.True);
}

Problem

I have a method with the following structure: ``` bool myMethod(some arguments) { //Show User Dialog } ``` The user dialog is shown which has 4 buttons, "Yes", "Yes To All", "No" , "No To All". When I run the test case, It shows the user dialog, but test case do not proceed until user clicks on any button. How do we cover such methods using nUnit Test case?

Original source