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
Another way to test your configuration is by having a test suite that tests your app end-to-end. Although end-to-end tests nominally test use cases they indirectly check that your app is configured correctly, (that all the dependencies are wired, etc etc). Unit tests on the other hand should focus exclusively on the domain, and not on the context in which your code is deployed.
I also agree with NamshubWriter's answer. I'm am not against tests that check configuration as long as they are grouped in a separate test suite to your unit tests.