How to test exceptions in Grails using Spock.

MyObject.groovy

package myapp.mypackage


/**
 * Just an example of a domain class.
 * @author andrezrv
 */
class MyObject {
	
	String name
	String value
	
	/**
	 * Get a an object given its name.
	 * 
	 * @param name
	 * @return MyObject
	 */
	static def obtain( name ) {
		
		def myObject = MyObject.findByName( name )
		
		if ( !myObject.equals( null ) ) {
			return myObject
		}

		throw new Exception( 'Object not found' )
		
	}
	
}

TestCaseSpec.groovy

package myapp.mypackage

import grails.test.mixin.TestFor
import grails.test.mixin.Mock
import spock.lang.Specification

/**
 * See the API for {@link grails.test.mixin.services.ServiceUnitTestMixin} for usage instructions
 * @author andrezrv
 */
@TestFor( MyObject )
@Mock( [ MyObject ] )
class MyServiceSpec extends Specification {

void testObtain() {
		
	def myObject = new MyObject( name: 'Foo', value: 'Bar' )
	myObject.save()
	
	def myIncompleteObject = new MyObject()
		
	given: // Obtain object with a valid instance.
		def result = MyObject.obtain( myObject.name )
	expect: 
		myObject == return
			
	when : // Obtain object with an incomplete unsaved instance.
		result = MyObject.obtain( myIncompleteObject )
	then:
		Exception e = thrown()
		'Object not found' == e.message
		
	}
	
}