Fix#3625. With a fraction format, PhpSpreadsheet wrote an integer as
the integer alone, so 1 formatted with `0/0` was `1`. Excel writes
`1/1`: a format with no integer part always shows a fraction. Excel
also shows the fraction when the last numerator placeholder is 0, so 1
formatted with `0 0/0` is `1 0/1`; with a `?` or `#` numerator
placeholder the fraction is left out, as before.
The `#` and `0` placeholders were replaced by `?` before
FractionFormatter saw the format, so the replacement moves into
FractionFormatter, which first notes whether the numerator ends in 0.
While we might never be able to have 100% of our code strict, we can at
the very least do it for all of our tests. This ensures that our tests
are using our API with the types as intended by the test author, and not
silently be cast to what our API requires.
ybai08
Adrien Crivelli
MarkBaker