Grails spock test fails with "GroovyCastException: Cannot cast object" - validation

Question

I have a simple class that I'm writing a test for. Something weird happens when I call validate() on an instance of that class, which relates to my custom validator for my date property. If my custom validator calls a static method, everything seems to work fine. However, if I call a non-static method (which I need to as I need to check some other properties of my instance) I get the following error:
Condition failed with Exception:
testDate.validate(['date']) == valid
| |
| org.codehaus.groovy.runtime.typehandling.GroovyCastException: Cannot cast object 'class hegardt.backend.grails.model.person.TestDate' with class 'java.lang.Class' to class 'hegardt.backend.grails.model.person.TestDate'
| at hegardt.backend.grails.model.person.TestDate._clinit__closure1$_closure2(TestDate.groovy:20)
| at groovy.lang.Closure.call(Closure.java:405)
| at org.grails.datastore.gorm.validation.constraints.ValidatorConstraint.processValidate(ValidatorConstraint.java:100)
| at org.grails.datastore.gorm.validation.constraints.AbstractConstraint.validate(AbstractConstraint.java:88)
| at grails.gorm.validation.DefaultConstrainedProperty.validate(DefaultConstrainedProperty.groovy:601)
| at grails.validation.Validateable$Trait$Helper.doValidate(Validateable.groovy:192)
| at grails.validation.Validateable$Trait$Helper.validate(Validateable.groovy:163)
| at grails.validation.Validateable$Trait$Helper.validate(Validateable.groovy:129)
| at hegardt.backend.grails.model.person.TestDateSpec.test(TestDateSpec.groovy:15)
<hegardt.backend.grails.model.person.TestDate#48bb8764 date=null privateVar=false grails_validation_Validateable__beforeValidateHelper=org.grails.datastore.gorm.support.BeforeValidateHelper#1624fd07 grails_validation_Validateable__errors=grails.validation.ValidationErrors: 0 errors>
Here's my class definition:
#GrailsCompileStatic
class TestDate implements Validateable {
LocalDate date
boolean privateVar
static constraints = {
date nullable: true, validator: {LocalDate val -> validateDate(val)}
}
private validateDate(LocalDate val) { // If this method is static, everything works fine
return privateVar
}
}
and here's my test class
class TestDateSpec extends Specification {
#Unroll
void "test"() {
given:
TestDate testDate = new TestDate(date: date)
expect:
testDate.validate(['date']) == valid // This call fails for all 4 test cases...
where:
date | valid
null | true
LocalDate.now().plusDays(1) | false
LocalDate.now() | false
LocalDate.now() | true
}
}
PS
I have also tried without #GrailsCompileStatic but this just generates a different "cast" related error:
Condition failed with Exception:
testDate.validate(['date']) == valid
| |
| java.lang.IllegalArgumentException: object is not an instance of declaring class
| at org.grails.datastore.gorm.validation.constraints.builder.ConstrainedPropertyBuilder.doInvokeMethod(ConstrainedPropertyBuilder.java:65)
| at groovy.util.BuilderSupport.invokeMethod(BuilderSupport.java:64)
| at groovy.lang.GroovyObjectSupport.invokeMethod(GroovyObjectSupport.java:44)
| at hegardt.backend.grails.model.person.TestDate._clinit__closure1$_closure2(TestDate.groovy:19)
| at groovy.lang.Closure.call(Closure.java:405)
| at org.grails.datastore.gorm.validation.constraints.ValidatorConstraint.processValidate(ValidatorConstraint.java:100)
| at org.grails.datastore.gorm.validation.constraints.AbstractConstraint.validate(AbstractConstraint.java:88)
| at grails.gorm.validation.DefaultConstrainedProperty.validate(DefaultConstrainedProperty.groovy:601)
| at grails.validation.Validateable$Trait$Helper.doValidate(Validateable.groovy:192)
| at grails.validation.Validateable$Trait$Helper.validate(Validateable.groovy:163)
| at grails.validation.Validateable$Trait$Helper.validate(Validateable.groovy:129)
| at hegardt.backend.grails.model.person.TestDateSpec.test(TestDateSpec.groovy:15)
<hegardt.backend.grails.model.person.TestDate#1e742012 date=null privateVar=false grails_validation_Validateable__beforeValidateHelper=org.grails.datastore.gorm.support.BeforeValidateHelper#4f3967c7 grails_validation_Validateable__errors=grails.validation.ValidationErrors: 0 errors>

Answer 1

You are attempting to invoke an instance method (validateDate) from a static context (static constraints block) which is not allowed. You could mark validateDate as static but that moves the problem to privateVar which is an instance variable so you would not be able to reach that from a static method. It isn't clear what role that field plays so it isn't clear how best to deal with that, but the problem described in the question is caused because you are attempting to invoke an instance method from a static context.