Mock Objects in Play[2.0]

问题:

I want to test my Play application by providing mock objects during a test. Off the top of my head, there are a few ways to go about this.

1. Provide an alternative route files during testing
2. Use Dependency Injection, and check for a global value at runtime

I am not sure which is more feasible, or how to go about doing them. Any insight would be greatly appreciated.

回答1:

There is a third way; create your controller as a class or a trait for testing. Here is a simple example.

Your trait + implementation:

package services

trait MyService {
  def getUser(id:String):User
}

class ConcreteService extends MyService {
  override def getUser(id:String):User = {
  //Do real stuff
  }
}

In your controller class:

package controllers

import services._

class Users(service: MyService) extends Controller {
  def show(id: String) = Action {
    val user = service.getUser(id)
    Ok(views.html.user(user))
  }
}

object Users extends controllers.Users(new ConcreteService()) {}

Now you can run some unit tests..

package test

import controllers.Users
import play.api.test._
import play.api.test.Helpers._

import org.specs2.mock.Mockito
import org.specs2.mutable.Specification

class UsersSpec extends Specification with Mockito {
  val service = mock[MyService]

  "Users controller" should {
    "list users" in {
      //Insert mocking stuff here

      val users = new Users(service)
      val result = users.show("somerandomid")(FakeRequest())
      status(result) must equalTo(OK)
    }
  }
}

回答2:

I had the same question, and experimented some options:

• cake pattern
• injection via implicit
• spring

You can see the code on github here.

回答3:

My solution is similar to Blake's, except I did it without controllers as classes. You can check out the source here.

回答4:

For reference I have added an example of using Play's plugin framework for injecting mocked objects during testing.

1. http://www.underflow.ca/blog/935/mock-dependency-injection-in-play-2-0

Usage of this method a mocked plugin can be provided at test time:

class Test extends Specification {
    "application" should {
        "load mock dependency" in {
            running(TestServer(9000, FakeApplication(

            // The plugin at this class replaces the default
            additionalPlugins = Seq("test.MockInjector")

            )), HTMLUNIT) { browser =>
                browser.goTo("http://localhost:9000")

                // Test mock controller

            }
        }
    }
}

The MockInjector can be used to provide controller objects, or any other injectable component.

Note: I wrote the blog entry, and anyone is free to migrate any and all content from the blog to here.