"Tested" may be a bit of an exaggeration but there was a Grand Slam outside the museum at Fort Lewis, Washington State in the 80s. It was found on the ranges. My guess is that it was from B-17 trials & was jettisoned.
I seem to remember that it was not the blast itself but the shock wave produced that caused the main damage such that a near miss could do more than a direct hit. Barnes Wallis thought it up after he heard that shock waves from driving pilings was causing collateral damage at a site in London.