Some information from the WSJ article CONSO linked to:
"Boeing concluded pilots weren’t ever likely to encounter situations where the new anti-stall system kicked in, according to a Southwest memo reviewed by The Wall Street Journal. “They would never see the system in action,” a person familiar with Boeing’s development of the system said."
"..... Boeing’s position has some support. A top executive at a 737 MAX customer agreed pilots didn’t need to know the system’s details. “They’re not engineers and their job is to fly the aircraft,” this executive said."
"The FAA confirmed it is reviewing its decision to accept Boeing’s initial risk analyses of the automated system and other approved systems on the new plane. The FAA and Boeing also are developing a test of the entire MCAS system, which wasn’t previously required."