Deprecate floating-point values for size arguments

[Zac-HD]

hypothesis/hypothesis-python/src/hypothesis/internal/validation.py

Lines 102 to 111 in 859069c

	@check_function
	def check_valid_size(value, name):
	"""Checks that value is either unspecified, or a valid non-negative size
	expressed as an integer/float.
	Otherwise raises InvalidArgument.
	"""
	if value is None:
	return
	check_type(integer_types + (float,), value)

Sizes - the number of elements in a collection, bounded by min_size and max_size arguments, should always be integers. However, we currently also accept floats for these arguments! We should replace the check_type(integer_types + (float,), value) with

if isinstance(value, float):
    note_deprecation(...)
else:
    check_type(integer_types, value) 

And then write a test in hypothesis-python/tests/cover/test_validation.py that uses @checks_deprecated_behaviour, passes max_size=5.0 to lists(), and checks that the resulting lists are at most five elements long.

Finally, we should update the type hints for average_size arguments to # type: None as None is the only non-deprecated value.

[mridul2899]

Hey Zac!
I'm Mridul, a beginner in the field of open source development. I think I can resolve this issue. Can you assign this issue to me?

[Zac-HD]

Sure! It's all yours for the next week - just @-mention me if you have any more questions, and welcome to Hypothesis ✨

[math2001]

max_size=5.0 to lists(), and checks that the resulting lists are at most five elements long.

What should happen if someone passes 5.2 for example? I've quickly tested, and it seems to do some sort of math.ceil.

That seems to be handled on #1634 though, so should I just test "whole" float numbers for this issue?