Sample test using localstack + testcontainers in Spring

EmailTests.kt

package com.myapplication.email

import arrow.core.Either
import org.junit.jupiter.api.Assertions.fail
import org.junit.jupiter.api.Test
import org.springframework.boot.test.context.SpringBootTest
import org.springframework.test.context.ActiveProfiles
import org.testcontainers.containers.localstack.LocalStackContainer
import org.testcontainers.utility.DockerImageName
import software.amazon.awssdk.auth.credentials.AwsBasicCredentials
import software.amazon.awssdk.auth.credentials.StaticCredentialsProvider
import software.amazon.awssdk.regions.Region
import software.amazon.awssdk.services.ses.SesClient

@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
@ActiveProfiles("test")
class EmailClientTests {
  
    val email: Email = Email(
        to = "someone@example.com",
        subject = "Hi there!",
        body = "This is an email about some stuff",
        from = "sender@example.com"
    )

    @Test
    fun `send an email`() {
        when (EmailClient(awsTestSesClient()).send(email)) {
            is Either.Left -> fail("Email failed to send")
            is Either.Right -> return
        }
    }

    @Test
    fun `an email sending failure is handled`() {
        when (EmailClient(unauthenticatedAwsSesClient()).send(email)) {
            is Either.Left -> return
            is Either.Right -> fail("Email should not have been sent")
        }
    }

    fun awsTestSesClient(): SesClient = SesClient
        .builder()
        .endpointOverride(localstack.getEndpointOverride(LocalStackContainer.Service.S3))
        .credentialsProvider(
            StaticCredentialsProvider.create(
                AwsBasicCredentials.create(
                    localstack.accessKey, localstack.secretKey
                )
            )
        )
        .region(Region.of(localstack.region))
        .build()

    fun unauthenticatedAwsSesClient(): SesClient = SesClient
        .builder()
        .region(Region.of(localstack.region))
        .build()

    companion object {

        private val localstack = LocalStackContainer(DockerImageName.parse("localstack/localstack:0.11.3"))
            .withServices(LocalStackContainer.Service.SES)
            .withEnv("AWS_ACCESS_KEY_ID", "accesskey")
            .withEnv("AWS_SECRET_ACCESS_KEY", "secretkey")

        init {
            localstack.start()
            verifyEmail()
        }

        private fun verifyEmail() {
            val command = "aws ses verify-email-identity --email-address sender@example.com --region us-east-1 --endpoint-url http://localhost:4566"
            val result = localstack.execInContainer(*command.split(" ").toTypedArray())
            if (result.exitCode != 0) {
                throw Exception(result.stderr)
            }
        }
    }
}