Currently, we don't have any infrastructure to allow for CNI plugins to be used in `network/cni` isolator unit-tests. This forces us to mock CNI plugins that don't use new network namespaces leading to very restricting form of unit-tests.
Especially for port-mapper plugin, in order to test its DNAT functionality it will be very useful if we run the containers in separate network namespace requiring an actual CNI plugin.
The proposal is there to introduce a test filter called CNIPLUGIN, that gets set when CNI_PATH env var is set. Tests using the CNIPLUGIN filter can then use actual CNI plugins in their tests.