How can I force a build process to fail through a Unity editor script? - unity3d

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() {}

Answer 2

You can use OnValidate() which seems to be exactly what you're looking for.
Let's say you want to make sure a reference to a UI Text component is not null before building, in the script that should have the text reference, you add
private void OnValidate()
{
if (text == null)
{
Debug.LogError("Text reference is null!");
}
}
Having Debug.LogError calls during the build process actually cause the build to fail.