Add unittest

Add unittest

[   27s] + ./fixedbitset
[   27s]
[   27s] running 49 tests
[   27s] test binary_trait ... ok
[   27s] test bitand_assign_longer ... ok
[   27s] test bitand_assign_shorter ... ok
[   27s] test bitand_equal_lengths ... ok
[   27s] test bitand_first_larger ... ok
[   27s] test bitand_first_smaller ... ok
[   27s] test bitor_assign_shorter ... ok
[   27s] test bitor_assign_longer ... ok
[   27s] test bitor_equal_lengths ... ok
[   27s] test bitor_first_larger ... ok
[   27s] test bitor_first_smaller ... ok
[   27s] test bitxor_assign_longer ... ok
[   27s] test bitxor_first_smaller ... ok
[   27s] test bitxor_equal_lengths ... ok
[   27s] test bitxor_first_larger ... ok
[   27s] test bitxor_assign_shorter ... ok
[   27s] test copy_bit ... ok
[   27s] test count_ones ... ok
[   27s] test default ... ok
[   27s] test difference ... ok
[   27s] test count_ones_negative_range - should panic ... ok
[   27s] test count_ones_oob - should panic ... ok
[   27s] test display_trait ... ok
[   27s] test extend ... ok
[   27s] test extend_on_empty ... ok
[   27s] test from_iterator ... ok
[   27s] test count_ones_panic ... ok
[   27s] test from_iterator_ones ... ok
[   27s] test insert_range ... ok
[   27s] test intersection ... ok
[   27s] test is_disjoint_first_longer ... ok
[   27s] test is_disjoint_first_shorter ... ok
[   27s] test it_works ... ok
[   27s] test grow ... ok
[   27s] test iter_ones_range ... ok
[   27s] test ones ... ok
[   27s] test op_assign_ref ... ok
[   27s] test set_range ... ok
[   27s] test subset_superset_longer ... ok
[   27s] test subset_superset_shorter ... ok
[   27s] test symmetric_difference ... ok
[   27s] test test_is_clear ... ok
[   27s] test test_toggle ... ok
[   27s] test toggle_range ... ok
[   27s] test union ... ok
[   27s] test with_blocks ... ok
[   27s] test with_blocks_too_big ... ok
[   27s] test with_blocks_too_big_range_check ... ok
[   27s] test with_blocks_too_small ... ok
[   27s]
[   27s] test result: ok. 49 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.06s