Review 2: Testing

[jzmaddock]

We need more, specifically can we set it up to routinely CI run against decTest at https://speleotrove.com/decimal/dectest.html

I can probably help with a test harness if required, the format looks fairly straightforward.

It looks like at a minimum we should try to get the same values for the basic arithmetic operations, we should also be able to test whether the correct cohort member is produced, though that is a less important consideration for acceptance.

One side effect of this testing is that we need:

• A documented way to produce a specific cohort from a string.
• A documented way to print the actual cohort member rather than a normalised one.

Which also addresses some other review comments ;)

[mborland]

For decTest, due to license incompatibility the repo is here: https://github.com/cppalliance/decimal-dectest. I do have in this repo runners that run decTest: 2d8886f

On the cohort front I added a new charconv format called for cohorts preservation: https://develop.decimal.cpp.al/decimal/charconv.html. I also added an IEEE function that does exponent comparison of values for complete ordering: #1183. This is run in decTest.

[jzmaddock]

Thanks @mborland . Is it possible to bring the dectest test cases down onto CI just on demand, rather like we do for CMake or whatever, and integrate decTest testing into the main repro without actually distributing anything non Boost licensed?

[mborland]

Yes, right now the decTest repo is pulled in and tested for every commit or PR against this main decimal repo. I also put a small set of instructions in the decTest repo on how to use it locally should someone be so inclined.