How can I force a the build process to fail through a Unity editor script?

Question

I want to force the build process to fail if some validation conditions are not met.

I've tried using an IPreprocessBuildWithReport with no success:

using UnityEditor.Build;
using UnityEditor.Build.Reporting;

public class BuildProcessor : IPreprocessBuildWithReport
{
    public int callbackOrder => 0;

    public void OnPreprocessBuild(BuildReport report)
    {
        // Attempt 1
        // Does not compile because the 'BuildSummary.result' is read only
        report.summary.result = BuildResult.Failed;

        // Attempt 2
        // Causes a log in the Unity editor, but the build still succeeds
        throw new BuildFailedException("Forced fail");
    }
}

Is there any way to programmatically force the build process to fail?

I'm using Unity 2018.3.8f1.

Answer 1

As of 2019.2.14f1, the correct way to stop the build is to throw a BuildFailedException.

Other exception types do not interrupt the build.
Derived exception types do not interrupt the build.
Logging errors most certainly do not interrupt the build.

This is how Unity handles exceptions in PostProcessPlayer:

try
{
    postprocessor.PostProcess(args, out props);
}
catch (System.Exception e)
{
    // Rethrow exceptions during build postprocessing as BuildFailedException, so we don't pretend the build was fine.
    throw new UnityEditor.Build.BuildFailedException(e);
}

Just for clarity, this will NOT stop the build.:

// This is not precisely a BuildFailedException. So the build will go on and succeed.
throw new CustomBuildFailedException();

...

public class CustomBuildFailedException: BuildException() {}