Actually it is a bit more complicated. If Directv requests the test and it shows you cannot receive the station, the station pays, otherwise Directv pays for the test. If Directv refuses to test and you arrange for the test yourself, you pay regardless of the outcome.
From the FCC SHVERA Information Sheet:
Alternatively, if your household is predicted “served,” you may be able to get a waiver from the television stations that are predicted to serve your household over-the-air. You should ask your satellite company to request a waiver from the television station on your behalf. The station has 30 days from the date that it receives the waiver request to either grant or deny the request. If the station does not issue a decision within 30 days, the waiver is considered to be granted and the satellite company may provide the distant signals. The satellite company is not required to provide the distant signals and may choose to wait longer than 30 days before doing so.
If the station denies the waiver, you may request to have a signal strength test performed at your household to determine whether the TV station’s signal is at least Grade B intensity. Although the satellite carrier is not required to act on your request, if the carrier accepts your test request, the test should be performed within 30 days after the date that you submit your request. The test must be performed by an independent tester selected by the satellite carrier and the TV station. If the satellite carrier requests the test and the station’s signal exceeds the signal intensity standard, the satellite carrier pays for the test. If the station’s signal is determined not to exceed the signal intensity standard, the station pays for the test. If the satellite carrier does not act on your request for a signal strength test, or fails to respond to you within 30 days, and you reside in a DMA where the satellite carrier does not provide local-into-local service, you may arrange for the test yourself. You will have to pay for the test no matter what it shows and the price may include the cost for the tester to come to your house. The test must still be conducted by an independent tester that both the network station and the satellite carrier have approved.
If you ask Directv they would say that the policy regarding waiver waiting times is 45 days. This issue came up about a month ago for me. I had requested a waiver for CBS HD DNS. After 30 calendar days the waiver was still pending. No matter how many CSR's I spoke to + a couple of emails I was told that despite the law Directv gives the local stations 45 days. With nobody else left to call I started to wait again. Guess what? The damn station denied my waiver a couple of days later. Moral of the story is that although the law says one thing Directv made it's own policy (probably to make nice with local affiliates).