Refactor tests to split out common test types

[skirpichev]

It is better to not import from one test in other tests, I propose adding a utils module for common types / helpers.

Originally posted by @sobolevn in #111624 (comment)

For example:

cpython/Lib/test/test_complex.py

Lines 446 to 450 in 93206d1

	class float2:
	def __init__(self, value):
	self.value = value
	def __float__(self):
	return self.value

and

cpython/Lib/test/test_capi/test_getargs.py

Lines 102 to 104 in 93206d1

	class Float:
	def __float__(self):
	return 4.25

cpython/Lib/test/test_capi/test_getargs.py

Lines 113 to 123 in 93206d1

	class BadFloat:
	def __float__(self):
	return 687
	class BadFloat2:
	def __float__(self):
	return FloatSubclass(4.25)
	class BadFloat3(float):
	def __float__(self):
	return FloatSubclass(4.25)

we could unify to:

class FloatLike:
    def __init__(self, value):
        self.value = value

    def __float__(self):
        return self.value

Such support classes now scattered e.g. in Lib/test_float.py and in Lib/test_capi/test_getargs.py.

Linked PRs

• gh-111673: Refactor test_float/complex.py (split out support classes) #110956

[terryjreedy]

The appropriate place would be test.support. There is not yet a math support module.

[skirpichev]

Ok, #110956 is ready for review.

I did refactoring for Lib/test/test_float/complex.py and Lib/test/test_capi/test_long.py.