Grails metaclass modification not reliable within unit tests - unit-testing

Question

In a grails 2 project I'm using groovy's metaclass programming to add some methods to my domain classes.
Everything is working fine at runtime and I can run my integration tests fine.
But for unit tests I have some issues.
I have created a test mixin that is in charge of initializing the metaclass programming part.
This mixin is not running reliably:
the methods added to the metaclass are not available, or they are available after a first call, or they are available only after a previous grails test-app unit: command has been called.
This is quite a problem for continuous build.
You should be able to reproduce this issue (at least with grails 2.0.4) by
0) create a new grails projects
1) add a domain object
create-domain-class playground.Data
2) add this class to your src/groovy/playground dir
package playground
import grails.test.mixin.domain.DomainClassUnitTestMixin
import grails.test.mixin.support.GrailsUnitTestMixin
import org.codehaus.groovy.grails.commons.GrailsApplication
import org.codehaus.groovy.grails.commons.GrailsDomainClass
import org.junit.Before
class EnhanceDomainTestMixin {
boolean enhancerMethodCalled = false;
GrailsApplication application
MetaMethod mockDomainMethod
//replace the mockDomain Method from DomainClassUnitTestMixin with this closure
def enhancedMockDomain = { Class cl, List list ->
def enhanced =cl.metaClass.getMetaMethod("isEnhanced")
try {
//run the mockDomain method to have the mocked domain class registered in the grails application
mockDomainMethod.invoke(delegate, cl, list)
}
finally {
//enhance the grails domain with a new method
def domain = application.getDomainClass(cl.name) as GrailsDomainClass
domain.metaClass.isEnhanced = { return true; }
assert domain.newInstance().isEnhanced();
}
}
#Before void runDomainEnhancer() {
enhancerMethodCalled = true;
//GrailsUnitTestMixin.initGrailsApplication() should have already been called. (at least this was not an issue here)
application = GrailsUnitTestMixin.grailsApplication
//pick the mockDomain method
mockDomainMethod = DomainClassUnitTestMixin.metaClass.pickMethod("mockDomain", Class, List)
//if the picked mockDomain has never been enhanced, wrap it.
if(mockDomainMethod != enhancedMockDomain) {
DomainClassUnitTestMixin.metaClass.mockDomain = enhancedMockDomain
}
}
}
3) Add this small utils class (in test/unit/playground)
package playground
class TestSetup {
static Data d1
static void setup() {
d1 = new Data()
assert d1.isEnhanced()
}
}
4) Add these tests into the unit test already created by grails DataTests
package playground
import grails.test.mixin.*
#TestFor(Data)
#TestMixin(EnhanceDomainTestMixin)
class DataTests {
void testIsEnhancedLocal() {
assert enhancerMethodCalled
Data d = new Data()
assert d.isEnhanced()
}
void testIsEnhancedLocalSecondTime() {
assert enhancerMethodCalled
Data d = new Data()
assert d.isEnhanced()
}
void testIsEnhancedGlobalFirstTime() {
assert enhancerMethodCalled
TestSetup.setup()
assert TestSetup.d1 != null
}
void testIsEnhancedGlobalSecondTime() {
assert enhancerMethodCalled
TestSetup.setup()
assert TestSetup.d1 != null
}
}
Now run this command:
grails test-app unit:
you should have something like this output:
| Completed 4 unit tests, 4 failed in 1651ms
| Tests FAILED - view reports in target\test-reports
Now run the this command again (sometime one more is needed):
grails test-app unit: playground.DataTests
testMixin> grails test-app unit: playground.DataTests
| Completed 4 unit tests, 0 failed in 1384ms
| Tests PASSED - view reports in target\test-reports
So does anyone has a clue of why the metaClass modification is not reliable while running unit tests ? And how to workaround this issue ?

Answer 1

I had to use grailsApplication config in my domain class method. I ran into the same problem. Try using Holders.config instead of grailsApplication.config. It worked for me.