Skip to content

Commit

Permalink
pythongh-102433: Add tests for how classes with properties interact w…
Browse files Browse the repository at this point in the history
…ith `isinstance()` checks on `typing.runtime_checkable` protocols (python#102449)

Co-authored-by: Carl Meyer <carl@oddbird.net>
  • Loading branch information
2 people authored and iritkatriel committed Mar 12, 2023
1 parent 4c8bbe4 commit fde1a99
Showing 1 changed file with 88 additions and 0 deletions.
88 changes: 88 additions & 0 deletions Lib/test/test_typing.py
Original file line number Diff line number Diff line change
Expand Up @@ -2530,6 +2530,94 @@ def meth(x): ...
with self.assertRaises(TypeError):
isinstance(C(), BadPG)

def test_protocols_isinstance_properties_and_descriptors(self):
class C:
@property
def attr(self):
return 42

class CustomDescriptor:
def __get__(self, obj, objtype=None):
return 42

class D:
attr = CustomDescriptor()

# Check that properties set on superclasses
# are still found by the isinstance() logic
class E(C): ...
class F(D): ...

class Empty: ...

T = TypeVar('T')

@runtime_checkable
class P(Protocol):
@property
def attr(self): ...

@runtime_checkable
class P1(Protocol):
attr: int

@runtime_checkable
class PG(Protocol[T]):
@property
def attr(self): ...

@runtime_checkable
class PG1(Protocol[T]):
attr: T

for protocol_class in P, P1, PG, PG1:
for klass in C, D, E, F:
with self.subTest(
klass=klass.__name__,
protocol_class=protocol_class.__name__
):
self.assertIsInstance(klass(), protocol_class)

with self.subTest(klass="Empty", protocol_class=protocol_class.__name__):
self.assertNotIsInstance(Empty(), protocol_class)

class BadP(Protocol):
@property
def attr(self): ...

class BadP1(Protocol):
attr: int

class BadPG(Protocol[T]):
@property
def attr(self): ...

class BadPG1(Protocol[T]):
attr: T

for obj in PG[T], PG[C], PG1[T], PG1[C], BadP, BadP1, BadPG, BadPG1:
for klass in C, D, E, F, Empty:
with self.subTest(klass=klass.__name__, obj=obj):
with self.assertRaises(TypeError):
isinstance(klass(), obj)

def test_protocols_isinstance_not_fooled_by_custom_dir(self):
@runtime_checkable
class HasX(Protocol):
x: int

class CustomDirWithX:
x = 10
def __dir__(self):
return []

class CustomDirWithoutX:
def __dir__(self):
return ["x"]

self.assertIsInstance(CustomDirWithX(), HasX)
self.assertNotIsInstance(CustomDirWithoutX(), HasX)

def test_protocols_isinstance_py36(self):
class APoint:
def __init__(self, x, y, label):
Expand Down

0 comments on commit fde1a99

Please sign in to comment.