Java, Spock, and PowerMock

The thing I hate about Java is that at times, it’s just so verbose. And if you’re writing tests, it gets too time-consuming. Just the number of boilerplate you need makes it a little annoying to use.

I was playing around with Spock as a way to make test writing in Java much more fun. The problem is, the project I am currently working on is using a lot of static classes. So that’s one big hurdle I had to face.

I couldn’t find a lot of references about Spock natively being able to mock a static method for a Java class. But good thing is that we could use a Java Mocking Library. I decided to choose PowerMock simply because the project is already using it.

It took me a while to make Spock work with PowerMock though. I think that there’s not much references out there. There were a bunch of references saying that PowerMock couldn’t be used together with Spock. Luckily, I managed to stumble upon this repository which allowed me to successfully use PowerMock with Spock.

To use PowerMock, you need to add the following dependencies. The PowerMock :

<dependency>
  <groupId>org.powermock</groupId>
  <artifactId>powermock-module-junit4</artifactId>
  <version>${powermock.version}</version>
  <scope>test</scope>
</dependency>

<dependency>
  <groupId>org.powermock</groupId>
  <artifactId>powermock-module-junit4-rule</artifactId>
  <version>${powermock.version}</version>
  <scope>test</scope>
</dependency>

<dependency>
  <groupId>org.powermock</groupId>
  <artifactId>powermock-classloading-xstream</artifactId>
  <version>${powermock.version}</version>
  <scope>test</scope>
</dependency>

As of writing, I used 1.5.4 version of PowerMock.

My final test class looks something like this:

import org.junit.Rule
import org.mockito.Mockito
import org.powermock.api.mockito.PowerMockito
import org.powermock.core.classloader.annotations.PrepareForTest
import org.powermock.modules.junit4.rule.PowerMockRule
import spock.lang.Specification

@PrepareForTest([StaticClass.class])
public class FlightFormSpec extends Specification {

    @Rule PowerMockRule powerMockRule = new PowerMockRule();

    def "When mocking static"() {
        setup :
            PowerMockito.mockStatic(StaticClass.class)

        when :
            Mockito.when(StaticClass.getStaticMethod()).thenReturn("Philippines!");

        then :
            StaticClass.getStaticMethod() == "Philippines!"
    }
}

I hope that this article does help other people who were stuck at trying to mock static methods using Spock.