@Override
    @NotNull
    public BTreeMutable getMutableCopy() {
        final BTreeMutable result = new BTreeMutable(this);
        result.addExpiredLoggable(rootLoggable);
        return result;
    }
@Test
    public void testSplitLeft() {
        int s = 50;
        tm = new BTreeEmpty(log, createTestSplittingPolicy(), true, 1).getMutableCopy();

        for (int i = s - 1; i >= 0; i--) {
            getTreeMutable().put(kv(i, "v" + i));
        }

        checkTree(getTreeMutable(), s).run();

        long rootAddress = saveTree();

        checkTree(getTreeMutable(), s).run();

        reopen();

        t = new BTree(log, rootAddress, true, 1);
        checkTree(getTree(), s).run();
    }