Grails Controller Unit Test doesn't render page to response.text

Question

My env configs: Java 1.7u51, Grails 2.3.7

I'm trying to assert response.text in Controller Test but it always brings "".

What's happening?

This is my UserController

class UserController {

    def index() {
        flash.errors = "$params.secret"
        render view: "index", model: [model: params.toModel, 
                text: params.username]
    }
}

This is /user/index.gsp file

${text}

This is my Specification

@TestFor(UserController)
class UserControllerSpec extends Specification {

    def setup() {
    }

    def cleanup() {
    }

    void "test something"() {

        given:
            params.username = "USERNAME"
            params.password = "SECRET"
            params.toModel = "Model"

        when: 
            controller.index()

        then: 
            flash.errors
            view == "/user/index"
            params.username == response.text
            model.model == params.toModel
    }
}

And test report is:

Failure:  |
test something(teste.UserControllerSpec)
 |
Condition not satisfied:

params.username  == response.text
|      |         |  |        |
|      USERNAME  |  |        ""
|                |  org.codehaus.groovy.grails.plugins.testing.GrailsMockHttpServletResponse@46f29a61
|               false
|               8 differences (0% similarity)
|               (USERNAME)
|               (-------)
[username:USERNAME, password:SECRET, toModel:Model]

Answer 1

It is only the case of a template rendering where the content of the template is directly rendered to response as String. Hence response.text can only be used when a template is rendered unlike in this case where a view is being rendered.

In order to test rendering a view, GroovyPageUnitTestMixin has to be used as below:

import grails.test.mixin.TestMixin
import spock.lang.Specification
import grails.test.mixin.web.GroovyPageUnitTestMixin

@TestMixin(GroovyPageUnitTestMixin)
class UserControllerSpec extends Specification {
    def controller

    def setup(){
        controller = testFor(UserController)
    }

    void "test something"() {
        given:
            params.username = "USERNAME"
            params.password = "SECRET"
            params.toModel = "Model"

        when:
            controller.index()

        then:
            flash.errors
            view == "/user/index"
            model.model == params.toModel

            //method provided by mixin which mimics render method in 
            //controller. Make sure model is also passed in the map arg
            //since view uses model.text

            render(view: "/user/index", model: model) == 'USERNAME'
    }
}

Note:

• @TestFor is replaced with the Mixin in the test. Therefore, controller has to be mocked as seen in setup() using testFor() method.
• render() can also be used to test template rendering with the key template similar to the usage of key view in the map argument.