Random.Decimal with min = 0, max = decimal.MaxValue overflows

[Tvel]

Version Information

Software	Version(s)
Bogus NuGet Package	30.0.3
.NET Core?	3.1
.NET Full Framework?
Windows OS?	10
Linux OS?
Visual Studio?

What locale are you using with Bogus?

en-us

What is the expected behavior?

before v30 faker.Random.Decimal(0m, decimal.MaxValue) returned a value.

What is the actual behavior?

System.OverflowException
Value was either too large or too small for a Decimal.
at System.Number.ThrowOverflowException(TypeCode type)
at System.Decimal.DecCalc.ScaleResult(Buf24* bufRes, UInt32 hiRes, Int32 scale)
at System.Decimal.DecCalc.VarDecMul(DecCalc& d1, DecCalc& d2)
at System.Decimal.op_Multiply(Decimal d1, Decimal d2)
at Bogus.Randomizer.Decimal(Decimal min, Decimal max)

Can you identify the location in Bogus' source code where the problem exists?

https://github.com/bchavez/Bogus/blob/master/Source/Bogus/Randomizer.cs#L195
As I understand there was a change in the randomiser to make double values more precise.

If the bug is confirmed, would you be willing to submit a PR?

Yes

[bchavez]

Hi Tosil,

I think you might be correct. The recent Randomizer changes for decimal should be associated with PR #300.

If you could help with a new PR that fixes the OverflowException that would be wonderful, if not I will fix the issue tonight. A unit test that covers this OverflowException and maybe other edge cases would be great too.

Also, @logiclrd if you have any suggestions or comments on the issue, please let us know.

Thanks for bringing this to our attention.

Brian

[Tvel]

Hi Brian

I am not sure what is the best way to fix the overflow and I will not be able to work on this until at least monday, so if you or someone else want to fix it go ahead :). I am happy to help with unit tests or testing later.

Thanks!

[logiclrd]

I see what the problem is. Still thinking about how to correctly solve it, but the problem is that it's possible for the product of the initial result and (max - min) to exceed decimal.MaxValue.

[logiclrd]

(And yes, I wrote that code, so I ought to fix it :-D My apologies)

[bchavez]

@Tvel , @logiclrd

For the time being, I released Bogus v30.0.4 which Random.Decimal is reverted to a previous v29 implementation. So, you should be unblocked @Tvel while we work on a proper fix in PR #320.

The previous Random.Decimal code that throws the OverflowException was moved to the Bogus.Extensions namespace called Random.Decimal2() in case you still need the implementation that generates greater precision; however Decimal2() extension method will still throw OverflowException in the edge case you've discovered until we've fully worked out the details in #320.

Hope this helps.

Thanks,
Brian

[Tvel]

Thanks for the quick work from both of you!