CBA does require a little more testing than perhaps eWay so be prepared for some extra setup time.
The bank should supply you with the latest card numbers including testing instructions and error code responses - you must have these in order to meet their testing requirements.
The gateway can only be tested using specific dollar amounts (be sure to check your shipping as this may effect the total cart value) eg. .00c '0' response code for approved,.10c '1' response code. The module relays back to you at the top of the cart and the code is stored on the gateway so you can confirm this and the bank can see you have tested all the response coded.
Test results wont shown up unless you search for them.
For the testing be aware that specific CSC codes will also (again the request the testing documentation from the bank) generate additional codes that need to be tested and matched. For example using 102, 103, 104 as CSC will return specific error codes, 100 is approved and any other number combination is treated as valid.
Also note detailed CSC error codes may not show in the cart error message but should be viewed when searching transactions in the Commonwealth Bank Merchant admin area.