SpaceX has successfully tested [theverge.com] all three of its Falcon Heavy [wikipedia.org] first stage cores ahead of a planned maiden launch in November:
SpaceX CEO Elon Musk is hoping to launch his company's Falcon Heavy rocket for the first time in November [theverge.com], and with just a couple of months to go, the company announced that it has completed testing on all three of the rocket's first stage cores.
In the tweet, the company says that three first stage cores have completed their testing, and showed off a video of a static test of one of the cores. The company conducted its first static test of the Falcon Heavy's main core in May [theverge.com].
More about SpaceX's big year [spaceflightinsider.com].