How to prevent Debug.Assert(…) to show a modal dialog

Question:

When running at Debug mode, the Debug.Assert(…) method should pop up a modal dialog by default, and this could stop current running.

Solution:

1. All set to Release mode for source code, and re-build again, use released assembly, this would skip Debug code snippet.

2. If you cannot change the release mode from VS, or even you cannot get any source code, you can solve this problem by modifying the configuration file. (app.config)

<configuration>
  <system.diagnostics>
    <trace>
      <listeners>
        <clear/>
      </listeners>
    </trace>    
    <assert assertuienabled="false" />
  </system.diagnostics>
</configuration>

Ref: http://msdn.microsoft.com/en-us/library/ty5e4c4h.aspx

assertuienabled Attribute

Value	Description
true	Displays the message box. This is the default.
false	Does not display the message box.

3. Or we can create our customized Trace Listener to replace the default trace listener.

Here is Fail method in DefaultTraceListener class (System.Diagnostics.DefaultTraceListener)

public override void Fail(string message, string detailMessage)
{
    string str;
    StackTrace trace = new StackTrace(true);
    int startFrameIndex = 0;
    bool uiPermission = UiPermission;
    try
    {
        str = this.StackTraceToString(trace, startFrameIndex, trace.FrameCount - 1);
    }
    catch
    {
        str = "";
    }
    this.WriteAssert(str, message, detailMessage);
    if (this.AssertUiEnabled && uiPermission)
    {
        AssertWrapper.ShowAssert(str, trace.GetFrame(startFrameIndex), message, detailMessage);
    }
}

public static void ShowAssert(string stackTrace, StackFrame frame, string message, string detailMessage)
{
    ShowMessageBoxAssert(stackTrace, message, detailMessage);
}

And it pops up messagebox dialog by invoking the ShowAssert method.

We can now create a class that inherits from TraceListener, just need to override the Fail method. Here we output the trace message to console, no dialog pop-up.

public class MyTraceListener : TraceListener
 {
        public override void Write(string message)
        {
            Console.Write(message);
        }

        public override void WriteLine(string message)
        {
            Console.WriteLine(message);
        }

        public override void Fail(string message)
        {
            this.WriteLine(message);
        }

        public override void Fail(string message, string detailMessage)
        {
            this.WriteLine(string.Format("{0}: {1}", message, detailMessage));
        }
 }

Finally, we have to register this trace type by modifying our app configuration file.

<configuration>
  <system.diagnostics>
    <trace>
      <listeners>
        <clear/>
        <add type="DebugAssert.MyTraceListener, DebugAssert" name="MyTraceListener" />
      </listeners>
    </trace>    
    <assert assertuienabled="false" />
  </system.diagnostics>
</configuration>

Reference Articles:

http://www.alc.amadeus.com/content/public/alw/skillsoft/cbtlib/79986/80018/eng/thin/transcript.html

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