Trace.Assert not breaking, neither showing the message box

3
votes

I have a WPF application in which I'm moving data around on a Canvas. The problem started when I tried moving the data with the mouse like a freak.

Here's the sequence of the actions:

  • The MouseMove on the Canvas is triggered
  • In the MouseMove, I change some data
  • A Trace.Assert FAILS. The debugger does not break, neither is the message box
  • Another MouseMove is triggered
  • The data is changed again
  • An exception is thrown because of a reentrancy check in a collection. The debugger breaks there. The Assert message box was never shown.

The big problem here is that I can go back to the assert, but it's not the data at the time the assert failed, but the modified data at the end... so basically I can't debug that correctly.

Here's the stack trace, starting from the first MouseMove (Notice the ShowMessageBoxAssert and the fact that it still goes on...):

  .Models.FCurve.MoveKey(int keyIndex = 3, double keyTime = 1182.0) Line 199 C#
  .Models.FCurve.KeyTimeChanged(Models.FCurveKey timeChangeKey = {Models.FCurveKey}) Line 186 + 0x2d bytes C#
  .Models.FCurve.AddKeyToArray.AnonymousMethod(object sender = {Models.FCurveKey}, System.EventArgs args = {System.EventArgs}) Line 163 + 0x11 bytes C#
  [Native to Managed Transition] 
  [Managed to Native Transition] 
  .Models.FCurveKey.OnTimeChanged() Line 45 + 0x14 bytes C#
  .Models.FCurveKey..ctor.AnonymousMethod(object sender = {FCurveEditorTestApp.Impl.FCurveKeyImpl}, System.EventArgs args = {System.EventArgs}) Line 18 + 0x8 bytes C#
  [Native to Managed Transition] 
  [Managed to Native Transition] 
  FCurveEditorTestApp.exe!FCurveEditorTestApp.Impl.FCurveKeyImpl.OnTimeChanged() Line 43 + 0x14 bytes C#
  FCurveEditorTestApp.exe!FCurveEditorTestApp.Impl.FCurveKeyImpl.Time.set(double value = 1182.0) Line 34 + 0x8 bytes C#
  .Models.FCurveKey.Time.set(double value = 1182.0) Line 36 + 0x1b bytes C#
  .ViewModels.CurveKeyViewModel.X.set(double value = 1182.0) Line 32 + 0x2b bytes C#
  .ViewModels.CurveAreaViewModel.MoveSelectedItem.AnonymousMethod(ViewModels.CurveKeyViewModel key = {ViewModels.CurveKeyViewModel}) Line 127 + 0x2d bytes C#
  Collections.CollectionHelper.ForEach(System.Collections.Generic.IEnumerable source = {System.Linq.Enumerable.OfTypeIterator}, System.Action action = {Method = {Void b__8(ViewModels.CurveKeyViewModel)}}) Line 31 + 0xe bytes C#
  .ViewModels.CurveAreaViewModel.MoveSelectedItem(double deltaX = 693.0, double deltaY = 35.0) Line 126 + 0x63 bytes C#
  .Views.CurveAreaView._AreaCanvas_MouseMove(object sender = {System.Windows.Controls.Canvas}, System.Windows.Input.MouseEventArgs e = {System.Windows.Input.MouseEventArgs}) Line 195 + 0x2d bytes C#
  PresentationCore.dll!System.Windows.Input.MouseEventArgs.InvokeEventHandler(System.Delegate genericHandler, object genericTarget) + 0x34 bytes 
  PresentationCore.dll!System.Windows.RoutedEventArgs.InvokeHandler(System.Delegate handler, object target) + 0x27 bytes 
  PresentationCore.dll!System.Windows.RoutedEventHandlerInfo.InvokeHandler(object target, System.Windows.RoutedEventArgs routedEventArgs) + 0x3e bytes 
  PresentationCore.dll!System.Windows.EventRoute.InvokeHandlersImpl(object source = {System.Windows.Controls.Canvas}, System.Windows.RoutedEventArgs args = {System.Windows.Input.MouseEventArgs}, bool reRaised = false) + 0x1bf bytes 
  PresentationCore.dll!System.Windows.UIElement.RaiseEventImpl(System.Windows.DependencyObject sender = {System.Windows.Controls.Canvas}, System.Windows.RoutedEventArgs args = {System.Windows.Input.MouseEventArgs}) + 0x79 bytes 
  PresentationCore.dll!System.Windows.UIElement.RaiseEvent(System.Windows.RoutedEventArgs args = {System.Windows.Input.MouseEventArgs}, bool trusted) + 0x35 bytes 
  PresentationCore.dll!System.Windows.Input.InputManager.ProcessStagingArea() + 0x311 bytes 
  PresentationCore.dll!System.Windows.Input.InputManager.ProcessInput(System.Windows.Input.InputEventArgs input) + 0x42 bytes 
  PresentationCore.dll!System.Windows.Input.InputProviderSite.ReportInput(System.Windows.Input.InputReport inputReport) + 0x62 bytes 
  PresentationCore.dll!System.Windows.Interop.HwndMouseInputProvider.ReportInput(System.IntPtr hwnd, System.Windows.Input.InputMode mode, int timestamp, System.Windows.Input.RawMouseActions actions, int x, int y, int wheel) + 0x2e2 bytes 
  PresentationCore.dll!System.Windows.Interop.HwndMouseInputProvider.FilterMessage(System.IntPtr hwnd = 2628604, int msg = 512, System.IntPtr wParam = 1, System.IntPtr lParam = 30409804, ref bool handled = false) + 0x22b bytes 
  PresentationCore.dll!System.Windows.Interop.HwndSource.InputFilterMessage(System.IntPtr hwnd = 2628604, int msg = 512, System.IntPtr wParam = 1, System.IntPtr lParam = 30409804, ref bool handled = false) + 0x75 bytes 
  WindowsBase.dll!MS.Win32.HwndWrapper.WndProc(System.IntPtr hwnd = 2628604, int msg = 512, System.IntPtr wParam = 1, System.IntPtr lParam = 30409804, ref bool handled = false) + 0xbe bytes 
  WindowsBase.dll!MS.Win32.HwndSubclass.DispatcherCallbackOperation(object o) + 0x7a bytes 
  WindowsBase.dll!System.Windows.Threading.ExceptionWrapper.InternalRealCall(System.Delegate callback = {Method = {System.Object DispatcherCallbackOperation(System.Object)}}, object args = {MS.Win32.HwndSubclass.DispatcherOperationCallbackParameter}, bool isSingleParameter = true) + 0x8a bytes 
  WindowsBase.dll!System.Windows.Threading.ExceptionWrapper.TryCatchWhen(object source = {System.Windows.Threading.Dispatcher}, System.Delegate callback, object args, bool isSingleParameter, System.Delegate catchHandler = null) + 0x4a bytes 
  WindowsBase.dll!System.Windows.Threading.Dispatcher.WrappedInvoke(System.Delegate callback, object args, bool isSingleParameter, System.Delegate catchHandler) + 0x44 bytes 
  WindowsBase.dll!System.Windows.Threading.Dispatcher.InvokeImpl(System.Windows.Threading.DispatcherPriority priority, System.TimeSpan timeout, System.Delegate method, object args, bool isSingleParameter) + 0x91 bytes 
  WindowsBase.dll!System.Windows.Threading.Dispatcher.Invoke(System.Windows.Threading.DispatcherPriority priority, System.Delegate method, object arg) + 0x40 bytes 
  WindowsBase.dll!MS.Win32.HwndSubclass.SubclassWndProc(System.IntPtr hwnd = 2628604, int msg = 512, System.IntPtr wParam = 1, System.IntPtr lParam = 30409804) + 0xdc bytes 
  [Native to Managed Transition] 
  [Managed to Native Transition] 
  System.dll!System.Diagnostics.AssertWrapper.ShowMessageBoxAssert(string stackTrace, string message, string detailMessage) + 0x103 bytes 
  System.dll!System.Diagnostics.DefaultTraceListener.Fail(string message, string detailMessage) + 0xb2 bytes 
  System.dll!System.Diagnostics.DefaultTraceListener.Fail(string message) + 0xa bytes 
  System.dll!System.Diagnostics.TraceInternal.Fail(string message = "") + 0xb6 bytes 
  System.dll!System.Diagnostics.Trace.Assert(bool condition) + 0x1c bytes 
  .ViewModels.CurvePathViewModel.CurvePathViewModel(Models.FCurveKey startKey = {Models.FCurveKey}, Models.FCurveKey endKey = {Models.FCurveKey}, ViewModels.IInterpolationProvider interpolatorProvider = {ViewModels.InterpolationInfoProvider}) Line 29 + 0x4e bytes C#
  .ViewModels.CurvePathViewModel.CurvePathViewModel(ViewModels.CurveKeyViewModel startKey = {ViewModels.CurveKeyViewModel}, ViewModels.CurveKeyViewModel endKey = {ViewModels.CurveKeyViewModel}, ViewModels.IInterpolationProvider interpolatorProvider = {ViewModels.InterpolationInfoProvider}) Line 20 + 0x81 bytes C#
  .ViewModels.CurveViewModel.UpdateSegmentForKey(ViewModels.CurveKeyViewModel key = {ViewModels.CurveKeyViewModel}) Line 215 + 0x41 bytes C#
  .ViewModels.CurveViewModel.KeyViewModelsChanged(object sender = Count = 13, System.Collections.Specialized.NotifyCollectionChangedEventArgs e = {System.Collections.Specialized.NotifyCollectionChangedEventArgs}) Line 187 + 0x30 bytes C#
  [Native to Managed Transition] 
  [Managed to Native Transition] 
  WindowsBase.dll!System.Collections.ObjectModel.ObservableCollection.OnCollectionChanged(System.Collections.Specialized.NotifyCollectionChangedEventArgs e) + 0x50 bytes 
  WindowsBase.dll!System.Collections.ObjectModel.ObservableCollection.OnCollectionChanged(System.Collections.Specialized.NotifyCollectionChangedAction action, object item, int index, int oldIndex) + 0x34 bytes 
  WindowsBase.dll!System.Collections.ObjectModel.ObservableCollection.MoveItem(int oldIndex, int newIndex) + 0x6f bytes 
  WindowsBase.dll!System.Collections.ObjectModel.ObservableCollection.Move(int oldIndex, int newIndex) + 0xe bytes 
  Collections.CollectionSynchronizer._SourceList_CollectionChanged(object sender = Count = 13, System.Collections.Specialized.NotifyCollectionChangedEventArgs e = {System.Collections.Specialized.NotifyCollectionChangedEventArgs}) Line 239 + 0x45 bytes C#
  [Native to Managed Transition] 
  [Managed to Native Transition] 
  WindowsBase.dll!System.Collections.ObjectModel.ReadOnlyObservableCollection.OnCollectionChanged(System.Collections.Specialized.NotifyCollectionChangedEventArgs args) + 0x1d bytes 
  WindowsBase.dll!System.Collections.ObjectModel.ReadOnlyObservableCollection.HandleCollectionChanged(object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e) + 0xe bytes 
  [Native to Managed Transition] 
  [Managed to Native Transition] 
  WindowsBase.dll!System.Collections.ObjectModel.ObservableCollection.OnCollectionChanged(System.Collections.Specialized.NotifyCollectionChangedEventArgs e) + 0x50 bytes 
  WindowsBase.dll!System.Collections.ObjectModel.ObservableCollection.OnCollectionChanged(System.Collections.Specialized.NotifyCollectionChangedAction action, object item, int index, int oldIndex) + 0x34 bytes 
  WindowsBase.dll!System.Collections.ObjectModel.ObservableCollection.MoveItem(int oldIndex, int newIndex) + 0x6f bytes 
  WindowsBase.dll!System.Collections.ObjectModel.ObservableCollection.Move(int oldIndex, int newIndex) + 0xe bytes 
  .Models.FCurve.MoveKey(int keyIndex = 1, double keyTime = 489.0) Line 199 + 0x19 bytes C#
  .Models.FCurve.KeyTimeChanged(Models.FCurveKey timeChangeKey = {Models.FCurveKey}) Line 186 + 0x2d bytes C#
  .Models.FCurve.AddKeyToArray.AnonymousMethod(object sender = {Models.FCurveKey}, System.EventArgs args = {System.EventArgs}) Line 163 + 0x11 bytes C#
  [Native to Managed Transition] 
  [Managed to Native Transition] 
  .Models.FCurveKey.OnTimeChanged() Line 45 + 0x14 bytes C#
  .Models.FCurveKey..ctor.AnonymousMethod(object sender = {FCurveEditorTestApp.Impl.FCurveKeyImpl}, System.EventArgs args = {System.EventArgs}) Line 18 + 0x8 bytes C#
  [Native to Managed Transition] 
  [Managed to Native Transition] 
  FCurveEditorTestApp.exe!FCurveEditorTestApp.Impl.FCurveKeyImpl.OnTimeChanged() Line 43 + 0x14 bytes C#
  FCurveEditorTestApp.exe!FCurveEditorTestApp.Impl.FCurveKeyImpl.Time.set(double value = 489.0) Line 34 + 0x8 bytes C#
  .Models.FCurveKey.Time.set(double value = 489.0) Line 36 + 0x1b bytes C#
  .ViewModels.CurveKeyViewModel.X.set(double value = 489.0) Line 32 + 0x2b bytes C#
  .ViewModels.CurveAreaViewModel.MoveSelectedItem.AnonymousMethod(ViewModels.CurveKeyViewModel key = {ViewModels.CurveKeyViewModel}) Line 127 + 0x2d bytes C#
  Collections.CollectionHelper.ForEach(System.Collections.Generic.IEnumerable source = {System.Linq.Enumerable.OfTypeIterator}, System.Action action = {Method = {Void b__8(ViewModels.CurveKeyViewModel)}}) Line 31 + 0xe bytes C#
  .ViewModels.CurveAreaViewModel.MoveSelectedItem(double deltaX = 82.0, double deltaY = -9.0) Line 126 + 0x63 bytes C#
  Views.CurveAreaView._AreaCanvas_MouseMove(object sender = {System.Windows.Controls.Canvas}, System.Windows.Input.MouseEventArgs e = {System.Windows.Input.MouseEventArgs}) Line 195 + 0x2d bytes C#

The question would be: Why could this happen, and what should I do to make it break at the Assert time?

I thought of using an exception, maybe for debugging, but it's really an assert that I need. I'm thinking about all my others Asserts also, without needing to always convert them to exceptions for debugging...

2
c#wpfassert

2 Answers

5
votes

You can do this on a AppDomain-wide basis (Application-wide basis if your application has only one AppDomain) by writing your own TraceListener.

First create a class library project MyTraceListeners.dll containing an ExceptionTraceListener class:

public class ExceptionTraceListener : TraceListener
{
  public override void Write(string message)
  {
    // Do nothing
  }
  public override void Fail(string message)
  {
    Debugger.Break();  // or if you prefer, throw new Exception(...)
  }
  public override void Fail(string message, string detailMessage)
  {
    Debugger.Break();  // or if you prefer, throw new Exception(...)
  }
}

Now you can register this TraceListener in your application's .config file in the usual way:

<configuration>
  ...
  <system.diagnostics>
    ...
    <trace>
      <listeners>
        <clear />
        <add name="myListener" type="ExceptionTraceListener, MyTraceListeners" />
      </listeners>
    </trace>
  </system.diagnostics>
</configuration>

When you run your app with these .config file entries in place, the debugger will break immediately on every failed assertion.

Note also the <clear /> in this config file to clear any default TraceListeners listed in Machine.config. This is important because the default TraceListeners will receive the call before yours and still pop up the MessageBox.

0
votes

I have seen something like this before, a workaround that worked at the time was to add an if statement with the same condition as the assert, but negated, combined with a breakpoint set in the debugger on a statement in the then block of the if.