My own view is different; all the three are important coz first you present your CV which will determine if you will be contacted or not depending on the details in it and what the establishment wants from an employee.
Once the CV is Ok, comes the test to reaffirm your qualifications and to know how analytical you can be and once you are successful depending on their pass mark, you go to the next stage.
Once you are successful in the test, you will be called for an interveiw to know detailed things about you and as you put it in your CV and other things.
They are all interwoven coz without CV there is no test and therefore no interveiw but if compelled to choose one, its definately the CV coz U will use it all through the recruitment process and its the most valued document of all.