Un intento de hacer un código más funcional

TheCubeTestsFunc.groovy

package com.sourcebels

import groovy.util.GroovyTestCase;

class TheCube {
	
	public boolean containsPrimeNumber(String code1, String code2, String code3) {
	
		if (isPrimeNumber(sumDigits(code1)) ||
			isPrimeNumber(sumDigits(code2)) ||
			isPrimeNumber(sumDigits(code3)) ) {
			return true
		}
		return false
	}
	
	def isPrimeNumber = { number ->
		
		def result = true
		(2..number - 1).each { previous ->
			if(number % previous == 0)
				result = false
			}
		return result
	}
	
	def toInteger = {
		
		Integer.valueOf(it)
	}
	
	def sumDigits = {
	
		code -> code.collect { toInteger(it) }.sum()
	}
}

class TheCubeTests extends GroovyTestCase {
	
	private TheCube theCube
	
	public void setUp() {
		theCube = new TheCube()
	}
	
	public void testShouldReturnFalse() {
		
		assertFalse(theCube.containsPrimeNumber("6", "6", "6"))
		
		assertFalse(theCube.containsPrimeNumber("24", "44", "66"))
	}
	
	public void testShouldReturnTrue() {
		
		assertTrue(theCube.containsPrimeNumber("7", "6", "6"))
		assertTrue(theCube.containsPrimeNumber("6", "7", "6"))
		assertTrue(theCube.containsPrimeNumber("6", "6", "7"))
		assertTrue(theCube.containsPrimeNumber("6", "7", "7"))
		assertTrue(theCube.containsPrimeNumber("7", "7", "7"))
		
		assertTrue(theCube.containsPrimeNumber("6", "6", "43"))
		assertTrue(theCube.containsPrimeNumber("21", "6", "6"))
		
		assertTrue(theCube.containsPrimeNumber("34", "6", "6"))
		assertTrue(theCube.containsPrimeNumber("6", "34", "6"))
	}
}