How do I test Guice injections?

I gave to Google Guice the responsibility of wiring my objects. But, how can I test if the bindings are working well?

For example, suppose we have a class A which has a dependence B. How can I test that B is injected correctly?

class A {
    private B b;
    public A() {}

    @Inject
    public void setB(B b) {
        this.b = b
    }
}

Notice that A hasn't got a getB() method and I want to assert that A.b isn't null.