Grails - How to instantiate service in Controller when doing controller testing

Question

I am using a service in controller. I am writing unit test for the controller but I am unable to instantiate service in controller. It is always null.

if I instantiate service using new operator in Controller testing class. The services in the service class are not instantiated.

How can I instantiate a service in testing class?

Answer 1

You can let Spring do it for you.

A controller that depends on a service:

// grails-app/controllers/demo/DemoController.groovy
package demo

class DemoController {
    def helperService

    def index() {
        def answer = helperService.theAnswer
        render "The answer is ${answer}"
    }
}

The service:

// grails-app/services/demo/HelperService.groovy
package demo

class HelperService {

    def getTheAnswer() {
        42
    }
}

A unit test which injects the service:

// src/test/groovy/demo/DemoControllerSpec.groovy
package demo

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

@TestFor(DemoController)
class DemoControllerSpec extends Specification {

    static doWithSpring = {
        helperService HelperService
    }

    void "test service injection"() {
        when:
        controller.index()

        then:
        response.text == 'The answer is 42'
    }
}

A unit test which injects a fake version of the service:

// src/test/groovy/demo/AnotherDemoControllerSpec.groovy
package demo

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

@TestFor(DemoController)
class AnotherDemoControllerSpec extends Specification {

    static doWithSpring = {
        helperService DummyHelper
    }

    void "test service injection"() {
        when:
        controller.index()

        then:
        response.text == 'The answer is 2112'
    }
}

class DummyHelper {

    def getTheAnswer() {
        2112
    }
}