MSBuild custom task not fired in Visual Studio 2013

Question

In my solution I have a project with this single class:

using System.Windows;
using Microsoft.Build.Utilities;

namespace MetaCode
{
    public class MsBuildTask : AppDomainIsolatedTask
    {
        public override bool Execute()
        {
            System.Threading.Tasks.Task.Run(() => MessageBox.Show("12345678"));
            Log.LogMessage("12345678");
            return true;
        }
    }
}

I added this to another project's csproj file (let's call this project "Genesis" for now):

<Project ToolsVersion="4.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
    <UsingTask TaskName="MetaCode.MsBuildTask" AssemblyFile="c:\temp\MetaCode.dll" />
    ...
    <Target Name="AfterBuild">
        <MetaCode.MsBuildTask />
    </Target>
</Project>

But when I hit F5 in Visual Studio 2013 Pro, it builds the projects fine, but nothing happens... No MessageBox showing "12345678", and no "12345678" text in the "output" panel in Visual Studio. What am I missing here?

(the file "c:\temp\MetaCode.dll" exists in that location, and this is the output file of the above "MetaCode" project)

Answer 1

• First, increase message verbosity:

  Log.LogMessage(MessageImportance.High, "12345678");
  

And add a standard message just to make sure:

<Target Name="AfterBuild">
    <Message Text="About to run MsBuildTask" Importance="high" />
    <MetaCode.MsBuildTask />
</Target>

• Using task manager, kill all MSBuild.exe processes to clear all previous versions of your custom task.

• Rebuild the MSBuild task.

• Rebuild the consumer project and watch the output pane.