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About Marcin Zajaczkowski

Marcin Zajaczkowski
Marcin is an experienced architect who specializes in creating high quality software. Being under the impression of the Agile methodologies and the Software Craftsmanship movement, he believes in the value of good, testable and maintainable code. He aims to forge good software that makes the client delighted and the team proud of how the code itself looks.In his teaching, as a conference speaker, college lecturer, IT coach and trainer, he shows how to guide software development effectively using tests (with TDD, pair programming, Clean Code, design patterns, etc.) and maintaining a quality-oriented development environment (with CI, Sonar, automatic deployment, etc.).He is also a FOSS projects author and contributor, a Linux enthusiast.

Migrating Spock 1.3 tests to Spock 2.0

Get know what you can expect from Spock 2.0 M1 (based on JUnit 5), how to migrate to it in Gradle and Maven, and why it is important to report spotted problems :).

Important note. I definitely do not encourage you to migrate your real-life project to Spock 2.0 M1 for good! This is the first (pre-)release of 2.x with not finalized API, intended to gather user feedback related to internal Spock migration to JUnit Platform.

This blog post arose to try to encourage you to make a test migration of your projects to Spock 2.0, see what started to fail, fix it (if caused by your tests) or report it (if it is a regression in Spock itself). As a result – at the Spock side – it will be possible to improve the code base before Milestone 2. The benefit for you – in addition to contribution to the FOSS project :-) – will be awareness of required changes (kept in a side branch) and readiness to migration once Spock 2.0 is more mature.

I plan to update this blog post when the next Spock 2 versions are available.

Powered by JUnit Platform

The main change in Spock 2.0 M1 is migration to JUnit 5 (precisely speaking to execute tests with JUnit Platform 1.5, part of JUnit 5 instead of the JUnit 4 runner API). This is very convenient as Spock tests should be automatically recognized and executed everywhere the JUnit Platform is supported (IDEs, build tools, quality tools, etc.). In addition, the features provided by the platform itself (such as parallel test execution) should be (eventually) available also for Spock.

To bring Spock 2 to a Gradle project it is needed to bump the Spock version:

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testImplementation('org.spockframework:spock-core:2.0-M1-groovy-2.5')

and activate tests execution by JUnit Platform:

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test {
    useJUnitPlatform()
}

With Maven on the other hand, it is still required to switch to a never Spock version:

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<dependency>
  <groupId>org.spockframework</groupId>
  <artifactId>spock-core</artifactId>
  <version>2.0-M1-groovy-2.5</version>
  <scope>test</scope>
</dependency>

but that is all. The Surefire plugin (if you use version 3.0.0+) executes JUnit Platform tests by default, if junit-platform-engine (a transitive dependency of Spock 2) is found.

The minimal working project for Gradle i Maven is available from GitHub.

Other changes

Having such big change as migration to JUnit Platform, number of other changes in Spock 2.0 M1 is limited, to make finding a reason of potential regressions a little bit easier. As a side effects of the migration itself, the required Java version is 8.

In addition, all parameterized tests are (finally) “unrolled” automatically. That is great, however, currently there is no way to “roll” particular tests, as known from spock-global-unroll for Spock 1.x.

Some other changes (such as temporarily disabled SpockReportingExtension) can be found in the release notes.

More (possibly breaking) changes are expected to be merged into Milestone 2.

Issue with JUnit 4 rules

The tests using JUnit 4 @Rules (or @ClassRules) are expected to fail with an error message suggesting that requested objects were not created/initialized before a test (e.g. NullPointerException or IllegalStateException: the temporary folder has not yet been created) or were not verified/cleaned up after it (e.g. soft assertions from AssertJ). The Rules API is no longer supported by JUnit Platform. However, to make the migration easier (@TemporaryFolder is probably very often used in Spock-based integration tests), there is a dedicated spock-junit4 which internally wraps JUnit 4 rules into the Spock extensions and executes it in the Spock’s lifecycle. As it is implemented as a global extension, the only required thing to add is another dependency. In Gradle:

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testImplementation 'org.spockframework:spock-junit4:2.0-M1-groovy-2.5'

or in Maven:

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<dependency>
    <groupId>org.spockframework</groupId>
    <artifactId>spock-junit4</artifactId>
    <version>2.0-M1-groovy-2.5</version>
    <scope>test</scope>
</dependency>

That makes migration easier, but it is good to think about a switch to native Spock counterpart, if available/feasible.

Other issues and limitations

Spock 2.0 M1 is compiled and tested only with Groovy 2.5.8. As of M1, execution with Groovy 3.0 is currently blocked at runtime. Unfortunately, instead of a clear error message about incompatible Groovy version there is only a very cryptic error message:

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Could not instantiate global transform class org.spockframework.compiler.SpockTransform specified at
jar:file:/.../spock-core-2.0-M1-groovy-2.5.jar!/META-INF/services/org.codehaus.groovy.transform.ASTTransformation
because of exception java.lang.reflect.InvocationTargetException

It is already reported and should be enhanced by M2.

Sadly, the limitation to Groovy 2.5 only, reduces potential feedback from people experimenting with Groovy 3 which is pretty close to a stable version (RC2 as of 2019/2020). It’s especially inconvenient as many Spock tests just work with Groovy 3 (of course there are some corner cases). There is a chance that Spock 2 before getting final will be adjusted to changes in Groovy 3 or at least the aforementioned hard limitation will be lifted. In the meantime, it is required to test Groovy 3 support with the snapshot version – 2.0-groovy-2.5-SNAPSHOT (which has that check disabled).

Summary

The action to do after reading this post is simple. Try to temporarily play with Spock 2.0 M1 in your projects and report any spotted issues, to help make Spock 2.0 even better :).

Published on Java Code Geeks with permission by Marcin Zajaczkowski, partner at our JCG program. See the original article here: Migrating Spock 1.3 tests to Spock 2.0

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