Question

Here is a part of a code of a simple WPF application: 3 textboxes, a dropdownList and a button. By clicking a button, there will be checking of input values.

   private void Button_Click_1(object sender, RoutedEventArgs e)
    {
        if (textBox1.Text.Length>127)
            throw new ArgumentException();
        if (string.IsNullOrEmpty(textBox2.Text))
            errorsList.Add("You must to fill out textbox2");
        else if (string.IsNullOrEmpty(textBox3.Text))
           errorsList.Add("You must to fill out textbox3"); 
       else if
        {
            Regex regex = new Regex(@".........");
            Match match = regex.Match(emailTxt.Text);
            if (!match.Success)
                errorsList.Add("e-mail is inlvalid");
        }
        //.....
     }

I have to test it by using any Unit testing Framework. I wonder is it possible to do Unit testing here? I guess it is not, right?

Answer 1

It is not possible to unit test the current code you have without refactoring. You should encapsulate that logic in a ViewModel class. I guess you can have something like

DoTheJob(string1,string2,string3,...)

and error/errorList/exList as ObservableCollections into the viev model too.
With these precondition you can write a suite of unit tests checking your code behavior.