groovy/groovy-core/xdocs/unitTesting.wiki

1 Unit Testing with Groovy

By default Groovy unit test cases generate java bytecode and so are just the same
as any other Java unit test cases. One thing to watch is often Ant / Maven look 
for *.java files to find unit tests with pattern matching, rather than *.class files.
There's an option in Maven to ensure you search for classes (and so find any Groovy 
unit test cases) via this property 

{code:shell}
maven.test.search.classdir = true
{code}

Once you've got this enabled you can use Maven goals to run individual test cases like this 

{code:shell}
maven test:single -Dtestcase=foo.MyGroovyTest
{code}

1.1 Running GroovyUnitTests in IDEs

Most IDEs support JUnit but maybe don't yet handle Groovy (shame!:).
Firstly if you compile the groovy code to bytecode, then it'll just work in any JUnit IDE just fine. 

Sometimes though you want to just hack the unit test script and run from in your IDE without
doing a build. 
If you're IDE doesn't automatically recompile Groovy for you then there's 
a utility to help you run Groovy unit test cases inside any JUnit IDE without needing to 
run your Ant / Maven build. 

The {link:GroovyTestSuite|apidocs/groovy/util/GroovyTestSuite.html} class 
is a JUnit TestSuite which will compile and run a GroovyUnit test case
from a command line argument (when run as an application) or from the __test__ system property
when run as a JUnit test suite. 

To run the GroovyUnitTest as an application, just do the equivalent of this in your IDE 

{code:shell}
java groovy.util.GroovyTestSuite src/test/Foo.groovy
{code}

Or to run the test suite inside your IDE, just run the GroovyTestSuite test 
with this system property defined 

{code:shell}
-Dtest=src/test/Foo.groovy
{code}

Either of the above can really help improve the development experience of writing 
Groovy unit test cases in IDEs that don't yet support Groovy natively.