Fixed bug: in PHP versions less than 5.6.0, any request that didn't
attempt to add any groups would warn, because it would call array_fill()
with the second argument (num) equal to 0. From PHP 5.6.0, the num
argument to array_fill() is allowed to be 0.
Change-Id: I0c5772f15d8f550dc43fb37c3c58d15dd73ea584
The unit tests spend nearly half of their run time resetting the user table for
each test. But the majority of tests do not depend on the user table having the
exact value that the setup code resets it to, and do not need to modify the
user objects they require to run.
Fix that by providing an API for tests to get User objects, and to indicate
whether the User object will be subject to destructive modification or not.
This allows User objects to be reused across multiple unit tests.
Change-Id: I17ef1f519759c5e7796c259282afe730ef722e96
