Kotlin example

[eaxdev]

Added an example that shows how to use Testcontainers along with the Kotlin language and Spring Boot application. The example uses the GenericContainer and Redis

[bsideup]

While I like the idea of having a Kotlin-based example, I would use a different example:

1. the provided example is too heavy (it uses Kafka which will add 10-20 seconds to our CI)
2. it does not show how to set properties on containers, which is the biggest problem with Kotlin (see Problems with TestContainers and Kotlin #318)
3. while it's okay to have Kotlin example, I would keep the Gradle DSL consistent with the rest of the projects here, in Groovy

[eaxdev]

Hi, @bsideup .

1. Can I use Redis image as an example? Is it heavy?
2. Okay, are you suggesting we use this workaround?
3. Fixed

[bsideup]

@eaxdev

1. yes, Redis is a good candidate.
2. I would use something like this:

@ClassRule
@JvmField
val redis = object : GenericContainer<Nothing>("redis:3-alpine") {
	init {
		withExposedPorts(6379)
	}
}

(this is pretty aligned with the ideas we have about the next generation of our DSL)

[eaxdev]

1. I replaced the Kafka container with Redis
2. I did it, but through an object companion. That's because @ClassRule wants a static field

[eaxdev]

Hi, could you review the changes? All review comments have been addressed. Or need something else to fix? Thank!

[bsideup]

hi @eaxdev,

I just applied a few changes, should be good to merge after the CI reports green status :)

[bsideup]

@eaxdev merged. Thanks! 👍