Why is inclusion of Kafka breaking my Spring controller's unit test? - spring

Question

I am creating a Spring Boot web application that will utilise Kafka. I have created a trivial controller that will return a string.
// src/main/groovy/RootController.groovy
import org.springframework.stereotype.Controller
import org.springframework.web.bind.annotation.GetMapping
import org.springframework.web.bind.annotation.ResponseBody
/**
* Controller to serve the index page
*/
#Controller
class RootController {
/**
* Serves the index page
*
* #return A string to appear on the index page
*/
#GetMapping("/")
#ResponseBody
String loadPage() {
return "root/index"
}
}
I have a unit test for this that uses Spock.
// src/test/groovy/RootControllerTest.groovy
import org.springframework.test.context.web.WebAppConfiguration
import org.springframework.test.web.servlet.MockMvc
import org.springframework.test.web.servlet.setup.MockMvcBuilders
import spock.lang.Specification
import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.*;
import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.*;
#WebAppConfiguration
class RootControllerTest extends Specification {
MockMvc mockMvc
// Setup for tests happens here˚
void setup() {
mockMvc = MockMvcBuilders.standaloneSetup(new RootController()).build()
}
// Cleanup for tests happens here
void cleanup() {}
def "LoadPage should return the string root/index"() {
when: 'the loadPage endpoint is hit'
def response = mockMvc.perform(get("/"))
then: 'the method loadPage returns the string root/index'
response.andExpect(status().isOk())
.andExpect(content().string("root/index"))
}
}
When run, this test passes. I have the following build.gradle file that will build and run the tests.
buildscript {
repositories {
mavenCentral()
}
dependencies {
classpath("org.springframework.boot:spring-boot-gradle-plugin:1.5.1.RELEASE")
}
}
plugins {
id 'org.springframework.boot' version '1.5.1.RELEASE' // Spring Boot
}
group 'dummy'
version '1.0-SNAPSHOT'
task wrapper(type: Wrapper) {
gradleVersion = '3.1'
distributionUrl = "https://services.gradle.org/distributions/gradle-$gradleVersion-all.zip"
}
apply plugin: 'groovy'
sourceCompatibility = 1.8
def kafkaVersion = '0.10.0.0'
repositories {
maven {
name "confluent"
url "http://packages.confluent.io/maven/"
}
mavenCentral()
}
dependencies {
compile "org.codehaus.groovy:groovy-all:2.4.4" // Groovy version
compile "org.springframework.boot:spring-boot-starter-thymeleaf" // For thymeleaf
//compile "org.apache.kafka:kafka_2.11:${kafkaVersion}-cp1" // Kafka, as produced by confluent, hence -cp1 suffix
// Testing dependencies go here
testCompile "org.springframework:spring-test:4.3.6.RELEASE"
testCompile "org.spockframework:spock-core:1.0-groovy-2.4" // Spock (Mandatory)
}
However, when I uncomment the Kafka dependency, the build fails like this:
$ gradle clean test
:clean
:compileJava UP-TO-DATE
:compileGroovy
:processResources UP-TO-DATE
:classes
:compileTestJava UP-TO-DATE
:compileTestGroovy
:processTestResources UP-TO-DATE
:testClasses
:test
RootControllerTest > LoadPage should return the string root/index FAILED
java.lang.ExceptionInInitializerError at RootControllerTest.groovy:21
Caused by: java.lang.IllegalStateException at RootControllerTest.groovy:21
1 test completed, 1 failed
:test FAILED
FAILURE: Build failed with an exception.
What is it that is causing the failure please?