VSSDK009 Use approved VsTaskRunContext values with VsTaskLibraryHelper

Microsoft.VisualStudio.Shell.VsTaskLibraryHelper helpers such as StartOnIdle, RunAsync, and WithPriority schedule work on the UI thread or influence the priority used when switching to it. Only these VsTaskRunContext values are allowed:

• VsTaskRunContext.UIThreadBackgroundPriority
• VsTaskRunContext.UIThreadIdlePriority
• VsTaskRunContext.UIThreadNormalPriority

Examples of patterns that are flagged by this analyzer

using System.Threading.Tasks;
using Microsoft.VisualStudio.Shell;
using Microsoft.VisualStudio.Threading;

class MyPackage
{
    void M(JoinableTaskFactory joinableTaskFactory)
    {
        joinableTaskFactory.StartOnIdle(() => { }, VsTaskRunContext.BackgroundThread);
        joinableTaskFactory.RunAsync(VsTaskRunContext.CurrentContext, async () => await Task.Yield());
        joinableTaskFactory.WithPriority(VsTaskRunContext.UIThreadSend);
    }
}

Solution

Use one of the approved values instead.

using System.Threading.Tasks;
using Microsoft.VisualStudio.Shell;
using Microsoft.VisualStudio.Threading;

class MyPackage
{
    void M(JoinableTaskFactory joinableTaskFactory)
    {
        joinableTaskFactory.StartOnIdle(() => { }, VsTaskRunContext.UIThreadBackgroundPriority);
        joinableTaskFactory.RunAsync(VsTaskRunContext.UIThreadNormalPriority, async () => await Task.Yield());
        joinableTaskFactory.WithPriority(VsTaskRunContext.UIThreadIdlePriority);
    }
}