Gambas Selftest:OldBugs.BugStringToFloatConversion Was: Re: Preparing the release of Gambas 3.20

[Christof Thalhofer <chrisml@xxxxxxxxxxx>]

Am 04.01.25 um 12:13 schrieb Benoît Minisini:
> Le 04/01/2025 à 09:48, Christof Thalhofer a écrit :
> > Am 04.01.25 um 01:44 schrieb Benoît Minisini:
> >
> > > And for sure someone will find last minute blocking bugs...
> >
> > You could find one by yourself if you would have ran './test-fast'.
> >
> > > # 2 tests failed:
> > > # 2: OldBugs.BugStringToFloatConversion.25 -- # 4:
> > > OldBugs.BugStringToFloatConversion.29 -- #
> > > # FAILED

...

> This test is problematic.
>
> You cannot be sure that `Round(19.9,-2) = 19.9`, because 19.9 has no
> exact binary representation, neither 10^-2.
>
> As the algorithm of Round() slightly changed, the test does not pass
> anymore.

Thank you for the explanation. I am not a mathematician.

We have an explicit test for Float. What if we do this in Gambas3 
Selftest:OldBugs.BugStringToFloatConversion?

---------------------------------------------------------

Public Sub BugStringToFloatConversion()

  Dim f As Float

  f = 19.900000000000055
  Assert.Equals(f, 19.9000000000001)
  Assert.Approximate(Round(f, -2), 19.9, 1E-14)

  f = 19.9000000000001
  Assert.Equals(f, 19.9000000000001)
  Assert.Approximate(Round(f, -2), 19.9, 1E-14)

End

---------------------------------------------------------

This test passes.

Alles Gute

Christof Thalhofer

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