Accepting any Rng in RandMoney makes tests more flexible to use a
different Rng. Also, passing in the Rng clarifies the call sites, so
that they all use g_rand_ctx explicitly and consistently.
The global g_insecure_rand_ctx will be removed in the future, so
removing it from this helper is useful.
Also, tying the two concepts of the global internal RNGState and the
global test-only rng context is a bit confusing, because tests can
simply use the m_rng, if it exists. Also, tests may seed more than one
random context, or none at all, or a random context of a different type.
Fix all issues by moving the Reseed call to the two places where it is
used.
The existing code provides two randomness mechanisms for test purposes:
- g_insecure_rand_ctx (with its wrappers InsecureRand*), which during tests is
initialized using either zeros (SeedRand::ZEROS), or using environment-provided
randomness (SeedRand::SEED).
- g_mock_deterministic_tests, which controls some (but not all) of the normal
randomness output if set, but then makes it extremely predictable (identical
output repeatedly).
Replace this with a single mechanism, which retains the SeedRand modes to control
all randomness. There is a new internal deterministic PRNG inside the random
module, which is used in GetRandBytes() when in test mode, and which is also used
to initialize g_insecure_rand_ctx. This means that during tests, all random numbers
are made deterministic. There is one exception, GetStrongRandBytes(), which even
in test mode still uses the normal PRNG state.
This probably opens the door to removing a lot of the ad-hoc "deterministic" mode
functions littered through the codebase (by simply running relevant tests in
SeedRand::ZEROS mode), but this isn't done yet.
and drop the util/random dependency on util/setup_common.
This improves code separation and avoids creating a circular dependency if
setup_common needs to call the util/random functions.
