I don't like test as a cycle for women but if she's done it and likes it at that dose which seems high for a woman....than good for her I guess.
She can take b/c....nobody knows how she will react. She just has to wait and see. She may not lean out as much as she hopes due to the estrogen. Some women don't have a problem with cycling and birth control. Some do. Test is one of the compounds that more womens have problems with while using b/c.
Birth control can affect testosterone and make it less effective in some cases. It will decrease the levels of test. Test can also make b/c less effective. This all depends on your individual body chemistry, the type of b/c, etc.
This is something you will have to see for yourself. If you are worried about getting preggo use another method of protection. If you are worried about the test becoming less effective...just wait and see...it might and it might not.