Spocklight: Undo Changes in Java System Properties

If we need to add a Java system property or change the value of a Java system property inside our specification, then the change is kept as long as the JVM is running. We can make sure that changes to Java system properties are restored after a feature method has run. Spock offers the RestoreSystemProperties extension that saves the current Java system properties before a method is run and restores the values after the method is finished. We use the extension with the @RestoreSystemProperties annotation. The annotation can be applied at specification level or per feature method.

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Spocklight: Auto Cleanup Resources

Spcok has a lot of nice extensions we can use in our specifications. The AutoCleanup extension makes sure the close() method of an object is called each time a feature method is finished. We could invoke the close() method also from the cleanup method in our specification, but with the @AutoCleanup annotation it is easier and immediately shows our intention. If the object we apply the annotation to doesn’t have a close() method to invoke we can specify the method name as the value for the annotation. Finally we can set the attribute quiet to true if we don’t want to see any exceptions that are raised when the close() method (or custom method name, that is specified) is invoked.

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Spocklight: Optimize Run Order Test Methods

Spock is able to change the execution order of test methods in a specification. We can tell Spock to re-run failing methods before successful methods. And if we have multiple failing or successful tests, than first run the fastest methods, followed by the slower methods. This way when we re-run the specification we immediately see the failing methods and could stop the execution and fix the errors. We must set the property optimizeRunOrder in the runner configuration of the Spock configuration file. A Spock configuration file with the name SpockConfig.groovy can be placed in the classpath of our test execution or in our USER_HOME/.spock directory. We can also use the Java system property spock.configuration and assign the filename of our Spock configuration file.

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Spocklight: Include or Exclude Specifications Based On Class or Interface

In a previous post we saw how can use the Spock configuration file to include or exclude specifications based on annotations. Instead of using annotations we can also use classes to include or exclude specifications. For example we could have a base specification class DatabaseSpecification. Other specifications dealing with databases extend this class. To include all these specifications we use the DatabaseSpecification as value for the include property for the test runner configuration.

Because Java (and Groovy) doesn’t support real multiple inheritance this might be a problem if we already have specifications that extends a base class, but the base class cannot be used as filter for the include and exclude runner configuration. Luckily we can also use an interface as the value for the inclusion or exclusion. So we could simple create a marker interface and implement this interface for these specifications we want to include or exclude from the test execution.

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Spocklight: Including or Excluding Specifications Based On Annotations

One of the lesser known and documented features of Spock if the external Spock configuration file. In this file we can for example specify which specifications to include or exclude from a test run. We can specify a class name (for example a base specification class, like DatabaseSpec) or an annotation. In this post we see how to use annotations to have some specifications run and others not.

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Spock: Using ConfineMetaClassChanges when using MetaClass mocking

One of the handy features of Groovy is to change the behavior of classes using MOP (Meta-Object Protocol). We change the metaClass property of a class to alter an implementation. You can for example override a static method of a class. See the example below:

However this way of mocking has a nasty side effect. Since we apply changes on the User on class level, the changes are also applied in all our other test cases. This can have some unexpected behavior in your other tests

To prevent this Spock has introduced the @ConfineMetaClassChanges annotation. This annotation makes sure the class will return to its original state when it was used in our test.

See the example below:

Be aware: this means when some other test did changes to the User class without using @ConfineMetaClassChanges, these changes will be still applicable when the test which has @ConfineMetaClassChanges restores the User class to its old state.

Spocklight: Indicate Class Under Test with Subject Annotation

If we write a specification for a specific class we can indicate that class with the @Subject annotation. This annotation is only for informational purposes, but can help in making sure we understand which class we are writing the specifications for. The annotation can either be used at class level or field level. If we use the annotation at class level we must specify the class or classes under test as argument for the annotation. If we apply the annotation to a field, the type of the field is used as the class under test. The field can be part of the class definition, but we can also apply the @Subject annotation to fields inside a feature method.

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Spocklight: Assign Multiple Data Variables from Provider

We can write data driven tests with Spock. We can specify for example a data table or data pipes in a where: block. If we use a data pipe we can specify a data provider that will return the values that are used on each iteration. If our data provider returns multiple results for each row we can assign them immediatelly to multiple variables. We must use the syntax [var1, var2, var3] < < providerImpl to assign values to the data variables var1, var2 and var3. We know from Groovy the multiple assignment syntax with parenthesis ((var1, var2, var3)), but with Spock we use square brackets.

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