  reservoir_->RecordScore(-1.0);
  EXPECT_THAT(reservoir_->get_dividers(), ElementsAre(-1.0));
  reservoir_->RecordScore(10);
  EXPECT_THAT(reservoir_->get_dividers(), ElementsAre(-1.0, 10));
  reservoir_->RecordScore(2);
  EXPECT_THAT(reservoir_->get_dividers(), ElementsAre(-1.0, 2, 10));
  reservoir_->RecordScore(2);
  EXPECT_THAT(reservoir_->get_dividers(), ElementsAre(-1.0, 2, 2, 10));
}

// Check the RecordScore() function with splitting and merging.
TEST_F(BalancedReservoirTest, RecordScorelarge) {
  reservoir_->set_dividers_for_test({1.0, 2.0, 3.0, 4.0, 5.0});