Creating multiple instances of a mock object

[Vince O'Sullivan]

I modified the Publisher/Subscriber example to reject duplicate subscriber instances.  It ran and passed the test that I had created. I then added the following test to show that three different subscribers would each receive the message once, when piblished:

        @Test
        public void testPublish3()
        {
                // Set up test.
                final Publisher publisher = new Publisher();
                final Subscriber subscriber1 = context.mock(Subscriber.class);
                final Subscriber subscriber2 = context.mock(Subscriber.class);
                final Subscriber subscriber3 = context.mock(Subscriber.class);
                publisher.add(subscriber1);
                publisher.add(subscriber2);
                publisher.add(subscriber3);
                final String message = "message";

                // Set up expectations.
                context.checking(new Expectations() {{
                        exactly(1).of(subscriber1).receive(message);
                        exactly(1).of(subscriber2).receive(message);
                        exactly(1).of(subscriber3).receive(message);
                }});

                // Execute action.
                publisher.publish(message);

                // Verify results.
                context.assertIsSatisfied();
        }

This compiles fine but the test crashed with the following error:

java.lang.IllegalArgumentException: a mock with name subscriber already exists
        at org.jmock.Mockery.mock(Mockery.java:128)
        at org.jmock.Mockery.mock(Mockery.java:120)
        at jmock.PublisherTest.testPublish3(PublisherTest.java:61)  (i.e. where subscriber2 is declared, above).

How should I have written this test?

Thanks,
Vince.

[Steve Freeman-2]

JMock enforces that multiple mock instances of the same type should have different names. That's what the error message is saying. Normally the instance name is defaulted. You could try:

final Subscriber subscriber1 = context.mock(Subscriber.class, "first");
final Subscriber subscriber2 = context.mock(Subscriber.class, "second");
final Subscriber subscriber3 = context.mock(Subscriber.class, "third");

S.


On 14 Mar 2010, at 15:03, Vince O'Sullivan wrote:

> I modified the Publisher/Subscriber example to reject duplicate subscriber
> instances.  It ran and passed the test that I had created. I then added the
> following test to show that three different subscribers would each receive
> the message once, when piblished:
>
> @Test
> public void testPublish3()
> {
> // Set up test.
> final Publisher publisher = new Publisher();
> final Subscriber subscriber1 = context.mock(Subscriber.class);
> final Subscriber subscriber2 = context.mock(Subscriber.class);
> final Subscriber subscriber3 = context.mock(Subscriber.class);
> publisher.add(subscriber1);
> publisher.add(subscriber2);
> publisher.add(subscriber3);
> final String message = "message";
>
> // Set up expectations.
> context.checking(new Expectations() {{
> exactly(1).of(subscriber1).receive(message);
> exactly(1).of(subscriber2).receive(message);
> exactly(1).of(subscriber3).receive(message);
> }});
>
> // Execute action.
> publisher.publish(message);
>
> // Verify results.
> context.assertIsSatisfied();
> }
>
> This compiles fine but the test crashed with the following error:
>
> java.lang.IllegalArgumentException: a mock with name subscriber already
> exists
> at org.jmock.Mockery.mock(Mockery.java:128)
> at org.jmock.Mockery.mock(Mockery.java:120)
> at jmock.PublisherTest.testPublish3(PublisherTest.java:61)  (i.e. where
> subscriber2 is declared, above).
>
> How should I have written this test?
>
> Thanks,
> Vince.
>
> --
> View this message in context: http://old.nabble.com/Creating-multiple-instances-of-a-mock-object-tp27895401p27895401.html
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>
>
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Steve Freeman

Winner of the Agile Alliance Gordon Pask award 2006
Book: http://www.growing-object-oriented-software.com

[phone]
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[Vince O'Sullivan]

Sorted.  Thanks.  Vince.
(On chapter 6 of GOOS;)
---------------------------------------------------------------------------------------------------

JMock enforces that multiple mock instances of the same type should have different names. That's what the error message is saying. Normally the instance name is defaulted. You could try:

final Subscriber subscriber1 = context.mock(Subscriber.class, "first");
final Subscriber subscriber2 = context.mock(Subscriber.class, "second");
final Subscriber subscriber3 = context.mock(Subscriber.class, "third");

S.