For the McCarthy test, both hips have to be in a flexed position. The affected hip needs to be brought into extension. If this movement reproduces a painful click, the patient is suffering from a labral tear. 
- McCarthy JC, Noble P, Schuck M, Alusio FV, Wright J, Lee J. “Acetabular and labral pathology.” In: McCarthy JC, editor. Early hip disorders. New York7 Springer Verlag; 2003. p. 113-33.