KafkaTestUtils uses EmbeddedKafkaRule, impossible to use with JUnit5

[d35h]

When I use @EmbeddedKafka with JUnit5 and make use of the KafkaTestUtils, I have gotten the following exception during ./gradlew build command being executed:

e: Supertypes of the following classes cannot be resolved. Please make sure you have the required dependencies in the classpath:
    class org.springframework.kafka.test.rule.EmbeddedKafkaRule, unresolved supertypes: org.junit.rules.ExternalResource, org.junit.rules.TestRule
    class org.springframework.kafka.test.rule.KafkaRule, unresolved supertypes: org.junit.rules.TestRule
> Task :compileTestKotlin FAILED

FAILURE: Build failed with an exception.

After the investigation I figured out where the problem is:
I was using KafkaTestUtils#consumerProps to create properties of the consumer, however, the file KafkaTestUtils uses indirectly org.springframework.kafka.test.rule.EmbeddedKafkaRule, which is not supposed to be used together with JUnit5.

There are two methods: public static Map<String, Object> consumerProps(String group, String autoCommit, KafkaEmbedded embeddedKafka) and public static Map<String, Object> producerProps(KafkaEmbedded embeddedKafka), which both are marked as deprecated, and this two methods have EmbeddedKafkaRule as their argument, which is dependent on JUnit4 resources and this is why it did not work without dependencies of JUnit4

Would it be possible to have two separated utils files? One specifically for JUnit4 and another one for JUnit5?

My gradle file is:

  implementation("org.springframework.boot:spring-boot-starter")
    implementation("org.springframework.boot:spring-boot-starter-web")
    implementation("org.jetbrains.kotlin:kotlin-reflect")
    implementation("org.jetbrains.kotlin:kotlin-stdlib-jdk8")
    implementation("org.springframework.kafka:spring-kafka")
    implementation("org.simpleflatmapper:sfm-csv:$csvFormatter")
    implementation("com.amazonaws:aws-java-sdk:$awsJavaSdk")

    testImplementation("org.springframework.boot:spring-boot-starter-test") {
        exclude("junit", "junit")
    }
    testImplementation("cloud.localstack:localstack-utils:$localStackVersion")
    testImplementation("org.springframework.kafka:spring-kafka-test")
    testImplementation("org.junit.jupiter:junit-jupiter-api:$junitVersion")
    testRuntimeOnly("org.junit.jupiter:junit-jupiter-engine:$junitVersion")
    testRuntimeOnly("org.junit.vintage:junit-vintage-engine:$junitVersion")

My test is:

@ExtendWith(value = [SpringExtension::class])
@SpringBootTest
@EmbeddedKafka
@DirtiesContext
@TestInstance(PER_CLASS)
@DisplayName("Kafka and S3 integration tests")
class KafkaSaverTestsGitHub {

    @Suppress("SpringJavaInjectionPointsAutowiringInspection")
    @Autowired
    lateinit var kafkaBroker: EmbeddedKafkaBroker

    @Test
    fun shouldNotBeNull() {
        assertThat(kafkaBroker).isNotNull
    }

    private fun getConsumerConfig(): HashMap<String, Any> {
        val configs = HashMap(KafkaTestUtils.consumerProps("consumer", "false", kafkaBroker))
        configs[ConsumerConfig.AUTO_OFFSET_RESET_CONFIG] = "earliest"
        return configs
    }

[d35h]

Thank you in advance!

[Woodham]

I was keeping an eye on the other issue and wondering why I wasn't seeing the same problem as you - I think I must have worked around it by adding this dependency:

        <dependency>
            <groupId>org.junit.jupiter</groupId>
            <artifactId>junit-jupiter-migrationsupport</artifactId>
            <version>${junit-jupiter.version}</version>
            <scope>test</scope>
        </dependency>

From here: https://github.com/junit-team/junit5/tree/master/junit-jupiter-migrationsupport

This module provides support for JUnit 4 rules within JUnit Jupiter. Currently, this support is limited to subclasses of the org.junit.rules.Verifier and org.junit.rules.ExternalResource rules of JUnit 4, respectively.

While I agree ideally this should be changed in spring-kafka this should work around the issue in the meantime!

[d35h]

@Woodham thank you, your workaround is more elegant than the one I had

[artembilan]

Oh! That is really a good catch for that KafkaTestUtils.
We thought that static method with such a transitive dependency (I mean KafkaEmbedded extends EmbeddedKafkaRule implements KafkaRule) won't bring the ClassNotFoundException issue if it is not called explicitly.
But looks like such a lazy-load trick works only for classes.
Since we have deprecated those KafkaEmbedded-based method in the previous version it doesn't sound too harmful to remove them in the current one.
Fortunately we have that junit-jupiter-migrationsupport (thanks @Woodham for the pointer!) workaround for the current version.

@garyrussell , WDYT?

[garyrussell]

I would say, yes, we can remove the deprecated classes and methods in 2.3.