How do I get injected reference from Guice created instance?

['Danny S.' via google-guice]

I just started learning Google Guice and developed a first example from Guice 
git-hub <https://github.com/google/guice/wiki/Motivation>.
My code looks something like this example 
<https://github.com/philipjkim/guice-example>.

My scenario to which I have a question:

In the Guice-example the BillingService calls 
a CreditCardProcessor#charge(creditCard, amount).
The credit card and amount is set to the CreditCardProcessor.
My GuiceBillingService gets the CreditCardProcessor via injection and sets 
the credit card to it through #chargeOrder() of my BillingService.


My test case looks like this:
@Override
public void setUp() throws Exception {
injector = Guice.createInjector(new FakeBillingModule());
}

@Override
public void tearDown() throws Exception {
injector = null;
}
public void testSuccessfulCharge() {
    BillingService billingService = 
injector.getInstance(BillingService.class);
    
    Receipt receipt = billingService.chargeOrder(order, creditCard);
    assertTrue(receipt.hasSuccessfulCharge());
    assertEquals(16.8, receipt.getAmountOfCharge());
    
    FakeCreditCardProcessor processor = (FakeCreditCardProcessor) 
injector.getInstance(CreditCardProcessor.class);
    assertEquals(creditCard, processor.getCardOfOnlyCharge());
    assertEquals(16.8, processor.getAmountOfOnlyCharge());
    
    InMemoryTransactionLog transactionLog = (InMemoryTransactionLog) 
injector.getInstance(TransactionLog.class);
    assertTrue(transactionLog.wasSuccessLogged());
}


Currently my module-configuration binds the CreditCardProcessor in scope 
SINGLETON:

@Override
protected void configure() {
bind(TransactionLog.class).to(InMemoryTransactionLog.class).in(Scopes.SINGLETON);
bind(CreditCardProcessor.class).to(FakeCreditCardProcessor.class).in(Scopes.SINGLETON);
bind(BillingService.class).to(GuiceBillingService.class);
}


So if not SINGLETON then a new CreditCardProcessor is created and 
assertEquals(creditCard, processor.getCardOfOnlyCharge()); will fail.
If my module does not configure the processor in scope SINGLETON Guice 
creates a new object via injector.getInstance() - so far so good, but how 
it's possible to get the same CreditCardProcessor from BillingService from 
Guice instead of using getters from the BillingService-instance?

How can I get the same instance of CreditCardProcessor that has been 
changed within the BillingService?

If scope SINGLETON is used the scope applies to application what means that 
it's always the same instance when I run tests in parallel?

Whats the preferred way to get injected dependencies from a 
Guice-created-instance? Are getters a recommended solution? I thought - if 
I use a DI-framework it should be able to get all concrete instances from 
it instead...?!

Thanks for some advice and help!
-Danny

-- 
You received this message because you are subscribed to the Google Groups 
"google-guice" group.
To unsubscribe from this group and stop receiving emails from it, send an email 
to google-guice+unsubscr...@googlegroups.com.
To post to this group, send email to google-guice@googlegroups.com.
Visit this group at https://groups.google.com/group/google-guice.
To view this discussion on the web visit 
https://groups.google.com/d/msgid/google-guice/1156b28d-bda4-43a4-b337-861b8da7a8e8%40googlegroups.com.
For more options, visit https://groups.google.com/d/optout.