Cake.Frosting: How to run a task even though a previous task failed?

[StefanOssendorf]

Hello,

I've migrated our cake script to cake frosting and merged some of the azure pipelines into the cake pipeline.
Now I'm facing a problem with "publish test results".

My tasks are structured roughly:
A -> B -> C -> Dotnet Test -> Publish Test results
But when "Dotnet Test" fails the "Publish Test results" task is not executed. Is there a way to say "Execute even if one of the previous tasks failed"?

Thanks in advance
Stefan

[nils-a]

@StefanOssendorf kind of. You can override OnError in the task that fails (not the following) and make Cake not abort the build on that error.

As an example:

using System;
using Cake.Common.Diagnostics;
using Cake.Core;
using Cake.Frosting;

public static class Program
{
    public static int Main(string[] args)
    {
        return new CakeHost()
            .Run(args);
    }
}

[TaskName("WillFail")]
public sealed class WillFailTask : FrostingTask
{
    public override void Run(ICakeContext context)
    {
        throw new Exception("Boom!");
    }

    public override void OnError(Exception exception, ICakeContext context)
    {
        context.Information($"Well, well, an error of {exception.GetType().Name} occured.");
    }
}

[TaskName("Default")]
[IsDependentOn(typeof(WillFailTask))]
public class DefaultTask : FrostingTask
{
    public override void Run(ICakeContext context)
    {
        context.Information("Hello, from Default!");
    }
}

[nils-a]

I think this is not possible out-of-the-box. Maybe someone else has a better idea than I do.
My go at this would be:

using System;
using System.Collections.Generic;
using System.Linq;
using Cake.Common.Diagnostics;
using Cake.Core;
using Cake.Frosting;

public static class Program
{
    public static int Main(string[] args)
    {
        return new CakeHost()
            .UseContext<MyContext>()
            .UseTeardown<TeardownBuild>()
            .Run(args);
    }
}

public sealed class MyContext : FrostingContext
{
    public List<Exception> Exceptions = new ();
    
    public MyContext(ICakeContext context) : base(context)
    {
    }
}

public sealed class TeardownBuild : FrostingTeardown<MyContext>
{
    public override void Teardown(MyContext context, ITeardownContext info)
    {
        var lastEx = context.Exceptions.LastOrDefault();
        if (lastEx != null)
        {
            context.Error("There were exceptions in one of the previous tasks.");
            throw lastEx;
        }
    }
}

[TaskName("WillFail")]
public sealed class WillFailTask : FrostingTask<MyContext>
{
    public override void Run(MyContext context)
    {
        throw new Exception("Boom!");
    }

    public override void OnError(Exception exception, MyContext context)
    {
        context.Exceptions.Add(exception);
        context.Information($"Well, well, an error of {exception.GetType().Name} occured.");
    }
}

[TaskName("Default")]
[IsDependentOn(typeof(WillFailTask))]
public class DefaultTask : FrostingTask
{
    public override void Run(ICakeContext context)
    {
        context.Information("Hello, from Default!");
    }
}

Additionally, you could override ShouldRun in the tasks that can be skipped if an error occurred previously.

[StefanOssendorf]

Thank you for the example. I think I'll try that way next week. Maybe someone else answers in the meantime with a built-in answer :-).
Otherwise I'll mark this as answered next week.
Thanks again and have a nice weekend.

[devlead]

One way to do this would be to set a flag on the Context that would indicate a fail and fail in Teardown.

If it's just the test results you always want, then you could upload them in a try-finally block.

try
{
...DotNetTest...
}
finally
{ 
  AzurePipelines.Commands
        .PublishTestResults(new AzurePipelinesPublishTestResultsData {
            TestResultsFiles = testResults,
            MergeTestResults = true,
            Configuration = configuration,
            TestRunTitle = runTitle,
            TestRunner = AzurePipelinesTestRunnerType.VSTest
        });
}

https://cakebuild.net/api/Cake.Common.Build.AzurePipelines/IAzurePipelinesCommands/31048D96

[nils-a]

... or override Finally in the FrostingTask.

[StefanOssendorf]

I use a flag to fail in the global tear down. Thanks for your answers :-)