Example Grails Filter Unit Test

FooSpec.groovy

@TestFor(FooController)
@Mock(FooFilters)
class FooSpec extends Specification {

  FooService fooServiceMock

	def "testing a filter"() {
		given:
		defineBeans {
			fooService(MethodInvokingFactoryBean) {
				targetObject = this
				targetMethod = 'mockFooService'
			}
		}
		FiltersGralisPlugin.reloadFilters(grailsApplication, applicationContext)

		when:
		withFilters(action: 'list') {
			controller.list()
		}

		then:
		1 * fooService.bar() >> true
	}

	FooService mockFooService() {
		fooServiceMock = Mock(FooService)
		return fooServiceMock
	}
}

class FooService {
	boolean bar() { return true
}

class FooFilters {
	def fooService

	def filters = {
		list(controller: 'foo', action: 'list') {
			before = {
				return fooService.bar()
			}
		}
	}
}