Ability to clear trait selection

This should fulfill issue #7

xunit.runner.wpf/MainWindow.xaml

@@ -110,6 +110,11 @@
                                 <Setter Property="IsSelected" Value="{Binding Mode=TwoWay, Path=IsSelected}"/>
                             </Style>
                         </ListBox.ItemContainerStyle>
+                        <ListBox.ContextMenu>
+                            <ContextMenu>
+                                <MenuItem Header="Clear" Command="{Binding TraitsClearCommand}" />
+                            </ContextMenu>
+                        </ListBox.ContextMenu>
                         <i:Interaction.Triggers>
                             <i:EventTrigger EventName="SelectionChanged">
                                 <cmd:EventToCommand Command="{Binding TraitSelectionChangedCommand}" />

xunit.runner.wpf/ViewModel/MainViewModel.cs

@@ -50,6 +50,7 @@ namespace xunit.runner.wpf.ViewModel
             this.RunCommand = new RelayCommand(OnExecuteRun, CanExecuteRun);
             this.CancelCommand = new RelayCommand(OnExecuteCancel, CanExecuteCancel);
             this.TraitSelectionChangedCommand = new RelayCommand(OnTraitSelectionChanged);
+            this.TraitsClearCommand = new RelayCommand(OnTraitsClear);
         }
 
         private static bool TestCaseMatches(TestCaseViewModel testCase, SearchQuery searchQuery)
@@ -108,6 +109,7 @@ namespace xunit.runner.wpf.ViewModel
         public RelayCommand RunCommand { get; }
         public RelayCommand CancelCommand { get; }
         public ICommand TraitSelectionChangedCommand { get; }
+        public ICommand TraitsClearCommand { get; }
 
         public CommandBindingCollection CommandBindings { get; }
 
@@ -328,8 +330,6 @@ namespace xunit.runner.wpf.ViewModel
                 tc.State = TestState.NotRun;
             }
 
-            // TODO: Need a way to filter based on traits
-
             var runAll = TestCases.Count == this.allTestCases.Count;
             var testSessionList = new List<ITestSession>();
 
@@ -437,6 +437,14 @@ namespace xunit.runner.wpf.ViewModel
             FilterAfterDelay();
         }
 
+        private void OnTraitsClear()
+        {
+            foreach (var cur in this.traitCollectionView.Collection)
+            {
+                cur.IsSelected = false;
+            }
+        }
+
         public bool IncludePassedTests
         {
             get { return searchQuery.IncludePassedTests; }

xunit.runner.wpf/ViewModel/TraitViewModel.cs

@@ -9,13 +9,19 @@ namespace xunit.runner.wpf.ViewModel
 {
     public sealed class TraitViewModel : ViewModelBase
     {
-        public readonly string _name;
-        public readonly string _value;
+        private readonly string _name;
+        private readonly string _value;
+        private bool _isSelected;
 
         public string Name => _name;
         public string Value => _value;
         public string DisplayName => $"{Name}={Value}";
-        public bool IsSelected { get; set; }
+
+        public bool IsSelected
+        {
+            get { return _isSelected; }
+            set { Set(ref _isSelected, value, nameof(IsSelected)); }
+        }
 
         public TraitViewModel(string name, string value)
         {