Can I use prepareSpec without @AutoScan?

[dondod]

I currently use an approach like the following to set up a database schema before tests run. It needs to happen before any test class is loaded.

class KotestExtensions {
    @AutoScan
    class PrepareSpecTestListener : TestListener {
        override suspend fun prepareSpec(kclass: KClass<out Spec>) {
            // set up database, etc.
        }
    }
}

But this generates this warning:

Warning: Kotest autoscan is enabled. This means Kotest will scan the classpath for extensions that are annotated with @AutoScan.
 To avoid this startup cost, set autoscan to false by setting the system property 'kotest.framework.classpath.scanning.config.disable=true'. In 6.0 this value will default to true. For further details see 
https://kotest.io/docs/next/framework/project-config.html#runtime-detection

I've tried disabling autoscan in another project that doesn't need the database setup, and it speeds up the test startup by several seconds (maybe 5 or more).

Is there a way to use prepareSpec without using @AutoScan?

[Kantis]

You can define kotest.properties (details here) with the following content:

kotest.framework.classpath.scanning.config.disable=true
kotest.framework.classpath.scanning.autoscan.disable=true
kotest.framework.config.fqn=com.myproject.KotestConfig

Where com.myproject.KotestConfig is

object KotestConfig : AbstractProjectConfig() {
  override fun extensions() = listOf(
    PrepareSpecTestListener()
  )
}

That should get rid of runtime detection while also letting you configure Kotest.

[dondod]

Thanks! That almost worked.. I get an error though:

io.kotest.engine.spec.SpecInstantiationException: Could not create instance of class com.myproject.MySpec. Specs must have a public zero-arg constructor.
	at io.kotest.engine.spec.InstantiateSpecKt.javaReflectNewInstance(instantiateSpec.kt:46)
	at io.kotest.engine.spec.InstantiateSpecKt.createAndInitializeSpec(instantiateSpec.kt:30)
	at io.kotest.engine.spec.InstantiateSpecKt.instantiate(instantiateSpec.kt:11)
	at io.kotest.engine.spec.SpecRefKt.instance(SpecRef.kt:14)
	at io.kotest.engine.spec.SpecExecutor.createInstance-gIAlu-s(SpecExecutor.kt:63)
	at io.kotest.engine.spec.SpecExecutor.access$createInstance-gIAlu-s(SpecExecutor.kt:24)
	at io.kotest.engine.spec.SpecExecutor$execute$innerExecute$1.invokeSuspend(SpecExecutor.kt:40)
...

Would that be because I pass a mock into the spec constructor? e.g.,

class MySpec(@MockkBean private val foo: Foo) : DescribeSpec({
    //
})

[dondod]

Moving the parameters out of the MySpec constructor works, but then I need to use init {... and change the way all the passed-in (usually auto-wired) arguments are dealt with. This is a common pattern with Spring Boot (for better or worse), so I wonder if there's a way allow passing arguments to the spec constructors.

[Kantis]

@dondod sorry for taking so long.. It's because the SpringAutowireConstructorExtensions from kotest-extensions-spring relies on @AutoScan to be discovered. When you disable scanning, you need to also register this extension manually from your KotestConfig.

You probably also want to register the SpringExtension

[dondod]

Thanks @Kantis! This works well in many cases for me (reducing test startup time by 7-8 seconds), but now the mocks declared by @MockkBean only work once. I'll see if I can narrow down the cause.

[Kantis]

Feel free to post a small example repo 🙂

[dondod]

Thanks, I'll try that soon..