  The problem of constructing effective statistical tests for random number
generators (RNG) is considered. Currently, there are hundreds of RNG
statistical tests that are often combined into so-called batteries, each
containing from a dozen to more than one hundred tests.
  When a battery test is used, it is applied to a sequence generated by the
RNG, and the calculation time is determined by the length of the sequence and
the number of tests. Generally speaking, the longer the sequence, the smaller
deviations from randomness can be found by a specific test. So, when a battery
is applied, on the one hand, the "better" tests are in the battery, the more
chances to reject a "bad" RNG. On the other hand, the larger the battery, the
less time can be spent on each test and, therefore, the shorter the test
sequence. In turn, this reduces the ability to find small deviations from
randomness. To reduce this trade-off, we propose an adaptive way to use
batteries (and other sets) of tests, which requires less time but, in a certain
sense, preserves the power of the original battery. We call this method
time-adaptive battery of tests.
