For this test the gun might not be relevant. The answers are in the article originally posted:
"The F-35 will not do close air support mission the same way the A-10 does. It will do it very differently. The A-10 was designed to be low, and slow, and close to the targets it was engaging, relatively speaking," Frank Kendall III, undersecretary of defense for acquisition, technology and logistics, told the Senate panel Tuesday. "We will not use the F-35 in the same way as the A-10.."
"We're going to let the F-35 pilots take advantage of the systems on that aircraft ... and see how well the missions are carried out in terms of the ability to strike targets in a timely manner and accurately, and then report on that,"
"Different or not, the Pentagon expects the F-35 to come out the winner in the face-off because it can handle different roles."
"Clearly the F-35 should have an advantage in higher threat environments than the A-10 does,"