In reply to jj_bukhari:
It depends on your strategy for distributing the virtual interfaces to your environment. The test itself does not need the virtual interface. It is a transaction-level component. Only when you are using a configuration object to distribute the virtual interface through your system you woule do a get in the test component.
uvm_test_top is the implicit instannce name of the test component. If you are using this it is restricted to this component.