Handle subtypes in instance_of validator

hypothesis-python/src/hypothesis/searchstrategy/attrs.py

@@ -26,6 +26,7 @@
 from hypothesis.errors import ResolutionFailed
 from hypothesis.internal.compat import string_types, get_type_hints
 from hypothesis.utils.conventions import infer
+from hypothesis.searchstrategy.types import type_sorting_key
 
 
 def from_attrs(target, args, kwargs, to_infer):
@@ -107,17 +108,20 @@ def types_to_strategy(attrib, types):
  return st.one_of(*map(st.from_type, typ))
  return st.from_type(typ)
  elif types:
- # Multiple type validators. Pick common type(s) that satisfy all.
- # TODO: use a more sophisticated aggregation that understands subtypes,
- # generic types, etc. Consider pulling some code out of st.from_type?
+ # We have a list of tuples of types, and want to find a type
+ # (or tuple of types) that is a subclass of all of of them.
  type_tuples = [k if isinstance(k, tuple) else (k,) for k in types]
- return st.one_of(*map(st.from_type, ordered_intersection(type_tuples)))
+ # Flatten the list, and filter out types that would fail validation
+ allowed = [t for t in set(sum(type_tuples, ()))
+ if all(issubclass(t, tup) for tup in type_tuples)]
+ allowed.sort(key=type_sorting_key) # Sort so order is stable between runs
+ return st.one_of([st.from_type(t) for t in allowed])
 
  # Otherwise, try the `type` attribute as a fallback, and finally try
  # the type hints on a converter (desperate!) before giving up.
  if isinstance(getattr(attrib, 'type', None), type):
  # The convoluted test is because variable annotations may be stored
- # in string form, and pass through attrs unevaluated.
+ # in string form; attrs doesn't evaluate them and we don't handle them.
  # See PEP 526, PEP 563, and Hypothesis issue #1004 for details.
  return st.from_type(attrib.type)
 

hypothesis-python/src/hypothesis/searchstrategy/types.py

@@ -35,8 +35,8 @@ def type_sorting_key(t):
  if not isinstance(t, type):
  raise InvalidArgument('thing=%s must be a type' % (t,))
  if t is None or t is type(None): # noqa: E721
- return -1
- return issubclass(t, collections.abc.Container)
+ return (-1, repr(t))
+ return (issubclass(t, collections.abc.Container), repr(t))
 
 
 def try_issubclass(thing, maybe_superclass):

hypothesis-python/tests/cover/test_attrs_inference.py

@@ -37,6 +37,11 @@ class Inferrables(object):
  attr.validators.instance_of(str),
  attr.validators.instance_of((str, int, bool)),
  ])
+ validator_type_has_overlap = attr.ib(validator=[
+ attr.validators.instance_of(str),
+ attr.validators.instance_of((str, list)),
+ attr.validators.instance_of(object),
+ ])
  validator_optional = attr.ib(
  validator=attr.validators.optional(lambda inst, atrib, val: float(val))
  )