Allows for the division of grails tests into partitions with a view to running each partition on a separate machine or process.
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Grails Partition Tests Plugin

Allows for the division of Grails tests into partitions with a view to running each partition on a separate machine or process.


As the number of tests in a Grails application increases, build times can become excessively long - particularly with a large number of functional tests. A typical strategy to overcome this, on a continuous integration build, is to divide the build/test process into splits and have each split run on separate slaves in parallel. Grails provides a way to run specific test phases, test types and test patterns, it does not however provide a straightforward way to run partitioned tests i.e. “run half of all functional tests’. This plugin facilitates partitioning of tests for any given ‘grails test-app’ command by supplying 2 extra arguments: ‘split’ and ‘totalSplits’


Add a dependency for the plugin in BuildConfig.groovy:

plugins {
   test ":partition-tests:0.3"


The partition-test command takes all of the same arguments that test-app takes with the addition of the arguments: ‘split’ and ‘totalSplits’ (both are required)

Run all tests across all test phases with some optional test-app arguments

grails test partition-test "--split=1" "--totalSplits=1" --verbose --echoOut --stacktrace

identiacal to :

grails test-app --verbose --echoOut --stacktrace

Run the 1st half of all of the applications tests for all test phases and test types

grails test partition-test "--split=1" "--totalSplits=2"

Run the 1st third of all unit tests

grails test partition-test :unit "--split=1" "--totalSplits=3"

Run the 1st third of all spock tests in the unit test phase

grails test partition-test unit:spock "--split=1" "--totalSplits=3"

Run the 2nd fiftieth of all spock test in the functional test phase

grails test partition-test functional:spock "--split=2" "--totalSplits=50"

Deterministic splits

The test files are distributed across partitions based on a composite sort in the following order

  1. Test file size
  2. Test file path

i.e. the 1st file in the 1st partition will be the largest file, the 1st file in the second partition will be the 2nd largest file and so on..

If two test files have the same size and name (same file names but in different packages) the file's path is used as the secondary qualifier when distributing across partitions.


  1. Relies on any custom test types in your application to extend from GrailsTestTypeSupport (as is the standard Grails way to add additional test types).
    • The default Grails test type is: `JUnit4GrailsTestType ``
    • Spock uses: GrailsSpecTestType
  2. All test types must use the GrailsTestTypeSupport.eachSourceFile(Closure body) {..} closure to locate it's test source files
  3. When a grails environment is required for a test phase, it must be set using -Dgrails.env=test. The reason is because setting scriptEnv="test" in PartitionTest.groovy does not seem to set the environment to test as expected.


The root directory contains 2 grails projects. grails-partition-tests and app. grails-partition-tests is the plugin source and app is a basic grails app with some tests which can be use to verify the plugin. app is configured with grails.plugin.location.'partition-tests' which means the plugin is used "in-place". See for the grails commands used to test both the app and plugin.