We do not support the test/demo/sandbox mode of any payment service; we can only handle actual, live checkouts. For Authorize.Net, we simply transmit to them via secure channel the details provided by the buyer at checkout; what they do to verify that data and authorize/decline payment is handled entirely at their end, then we simply honor whatever response code they return back to us.
If you have Authorize.Net configured to require a legitimate billing address for the card account details provided, then that requirement should be respected for your E-junkie checkouts using Authorize.Net. To test this, you can put your Authorize.Net account into live processing mode and place a test order; if you make a successful test payment, you can then refund or void the payment once your testing is completed.