UnitTesting for WPF events

Question

Hi All,

I am kind of new to C# and WPF, even though I am on my way to create a web scratching application using WPF. I am almost finished with my code and its working good. Now I want to write a set of unit test cases for this particular project, I started using MSTest. But when coming to events and big methods I am struggling to write unit tests for the same. I am adding a code snippet from my code below, can anyone check and give an idea about how to write a unit test case for that particular part. It is an autocomplete text box, where based on the input it will filter and I wrote it inside a Get focus event. adding the code below

 

private void Moduletext_GotFocus(object sender, RoutedEventArgs e)
        {
            IEnumerable<JiffyUIFamiliarization.Common.Model.DataEntity.Module> module_list = parentWindow.createApp.GetModuleList();
            Popup pp = (Popup)module.Template.FindName("ScreenPopup", module);
            Label ll = (Label)module.Template.FindName("PopUpLabel", module);
            var targetTextBox = sender as TextBox;
            if (targetTextBox.Text == "Search..")
            {
                targetTextBox.Text = "";
            }
            //var targetTextBox = sender as TextBox;
            // var targetTextBox = targetComboBox?.Template.FindName("PART_EditableTextBox", targetComboBox) as TextBox;
            var targetComboBox = this.module;

            if (targetTextBox == null) return;

            targetComboBox.Tag = "TextInput";
            targetComboBox.StaysOpenOnEdit = true;
            targetComboBox.IsEditable = true;
            targetComboBox.IsTextSearchEnabled = false;

            targetTextBox.TextChanged += (o, args) =>
            {
                var textBox = (TextBox)o;

                var searchText = textBox.Text;

                if (targetComboBox.Tag.ToString() == "Selection")
                {
                    targetComboBox.Tag = "TextInput";
                    targetComboBox.IsDropDownOpen = true;
                }
                else
                {
                    if (targetComboBox.SelectionBoxItem != null)
                    {
                        targetComboBox.SelectedItem = null;
                        targetTextBox.Text = searchText;
                        //textBox.CaretIndex = MaxValue;
                        targetTextBox.SelectionStart = targetTextBox.Text.Length;
                    }

                    if (string.IsNullOrEmpty(searchText))
                    {
                        targetComboBox.Items.Filter = item => true;
                        targetComboBox.SelectedItem = default(object);
                    }
                    else
                        targetComboBox.Items.Filter = item =>
                                item.ToString().StartsWith(searchText, true, CultureInfo.InvariantCulture);

                    var presentList = module_list.Where(item => item.GivenName.StartsWith(searchText, StringComparison.InvariantCultureIgnoreCase));
                    if (presentList.Count() == 0)
                    {
                        ll.Content = $"Add {searchText}";
                        pp.IsOpen = true;
                    }

                    //Keyboard.ClearFocus();
                    //Keyboard.Focus(targetTextBox);
                    //targetComboBox.IsDropDownOpen = true;
                    targetTextBox.SelectionStart = targetTextBox.Text.Length;
                }
            };
        }

 Please help me to write a unit test case for this or give me a code sample.