Add tests for chnk_rpad()

        }

    }

}

SCENARIO(" underrun distance can be computed correctly ",

         "[utils][numeric][chnk_rpad]") {

    GIVEN(" a block size ") {

        const std::size_t block_size = GENERATE(filter(

                [](uint64_t bs) { return is_power_of_2(bs); }, range(0, 100000)));

        WHEN(" offset is smaller than block_size ") {

            AND_WHEN(" offset equals 0 ") {

                const uint64_t offset = 0;

                CAPTURE(offset, block_size);

                THEN(" the computed underrun distance equals block_size ") {

                    const uint64_t underrun = chnk_rpad(offset, block_size);

                    const uint64_t expected_underrun = block_size;

                    REQUIRE(underrun == expected_underrun);

                }

            }

            AND_WHEN(" 0 < offset < block_size ") {

                const uint64_t offset = GENERATE_COPY(take(

                        test_reps, random(std::size_t{0}, block_size - 1)));

                CAPTURE(offset, block_size);

                THEN(" the computed underrun distance equals offset ") {

                    const uint64_t underrun = chnk_rpad(offset, block_size);

                    const uint64_t expected_underrun = block_size - offset;

                    REQUIRE(underrun == expected_underrun);

                }

            }

            AND_WHEN(" offset equals block_size - 1 ") {

                const uint64_t offset = block_size - 1;

                CAPTURE(offset, block_size);

                THEN(" the computed underrun distance equals block_size - 1 ") {

                    const uint64_t underrun = chnk_rpad(offset, block_size);

                    const uint64_t expected_underrun = block_size - offset;

                    REQUIRE(underrun == expected_underrun);

                }

            }

        }

        WHEN(" offset equals block_size ") {

            const uint64_t offset = block_size;

            CAPTURE(offset, block_size);

            THEN(" the computed underrun distance equals block_size ") {

                const uint64_t underrun = chnk_rpad(offset, block_size);

                const uint64_t expected_underrun = block_size;

                REQUIRE(underrun == expected_underrun);

            }

        }

        WHEN(" offset is larger than block_size ") {

            const uint64_t offset = GENERATE_COPY(

                    take(test_reps, random(block_size, block_size * 31)));

            CAPTURE(offset, block_size);

            THEN(" the computed underrun distance equals the difference between "

                 "offset and its closest block's right boundary ") {

                const uint64_t underrun = chnk_rpad(offset, block_size);

                const uint64_t expected_underrun =

                        static_cast<uint64_t>(offset / block_size + 1) *

                                block_size -

                        offset;

                REQUIRE(underrun == expected_underrun);

            }

        }

    }

}