Improving tests and documentation in memory module

[mnemonikr]

Improving tests and documentation in memory module

[mnemonikr]

All lines are practically covered. The only uncovered line is testing the conversion failure from usize to u64. This can theoretically fail but is machine-dependent.

The region coverage is substantially lower due to regions that are defined in the test code but not exercised (e.g. calls with ? that are expected to succeed). Unfortunately the test code is measured, and can't avoid this until rust-lang/rust#84605 is resolved.

Filename                      Regions    Missed Regions     Cover   Functions  Missed Functions  Executed       Lines      Missed Lines     Cover    Branches   Missed Branches     Cover
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
src/mem.rs                        426                42    90.14%          73                 1    98.63%         782                 3    99.62%           0                 0         -