Merge pull request #4259 from tybug/typing

Add type hints to `strategies.py`

Author: Liam-DeVoe

hypothesis-python/RELEASE.rst

@@ -0,0 +1,3 @@
+RELEASE_TYPE: patch
+
+Fixes a bug since around :ref:`version 6.124.4 <v6.124.4>` where we might have generated ``-0.0`` for ``st.floats(min_value=0.0)``, which is unsound.

hypothesis-python/src/hypothesis/control.py

@@ -12,8 +12,9 @@
 import math
 import random
 from collections import defaultdict
+from collections.abc import Sequence
 from contextlib import contextmanager
-from typing import Any, NoReturn, Optional, Union
+from typing import Any, Callable, NoReturn, Optional, Union
 from weakref import WeakKeyDictionary
 
 from hypothesis import Verbosity, settings
@@ -126,10 +127,15 @@ def deprecate_random_in_strategy(fmt, *args):
 
 
 class BuildContext:
-    def __init__(self, data, *, is_final=False, close_on_capture=True):
-        assert isinstance(data, ConjectureData)
+    def __init__(
+        self,
+        data: ConjectureData,
+        *,
+        is_final: bool = False,
+        close_on_capture: bool = True,
+    ) -> None:
         self.data = data
-        self.tasks = []
+        self.tasks: list[Callable[[], Any]] = []
         self.is_final = is_final
         self.close_on_capture = close_on_capture
         self.close_on_del = False
@@ -140,9 +146,17 @@ def __init__(self, data, *, is_final=False, close_on_capture=True):
             defaultdict(list)
         )
 
-    def record_call(self, obj, func, args, kwargs):
+    def record_call(
+        self,
+        obj: object,
+        func: object,
+        args: Sequence[object],
+        kwargs: dict[str, object],
+    ) -> None:
         self.known_object_printers[IDKey(obj)].append(
-            lambda obj, p, cycle, *, _func=func: p.maybe_repr_known_object_as_call(
+            # _func=func prevents mypy from inferring lambda type. Would need
+            # paramspec I think - not worth it.
+            lambda obj, p, cycle, *, _func=func: p.maybe_repr_known_object_as_call(  # type: ignore
                 obj, cycle, get_pretty_function_description(_func), args, kwargs
             )
         )

hypothesis-python/src/hypothesis/core.py

@@ -996,8 +996,9 @@ def run(data):
             except TypeError as e:
                 # If we sampled from a sequence of strategies, AND failed with a
                 # TypeError, *AND that exception mentions SearchStrategy*, add a note:
-                if "SearchStrategy" in str(e) and hasattr(
-                    data, "_sampled_from_all_strategies_elements_message"
+                if (
+                    "SearchStrategy" in str(e)
+                    and data._sampled_from_all_strategies_elements_message is not None
                 ):
                     msg, format_arg = data._sampled_from_all_strategies_elements_message
                     add_note(e, msg.format(format_arg))

hypothesis-python/src/hypothesis/internal/conjecture/data.py

@@ -793,6 +793,9 @@ def __init__(
         self._observability_predicates: defaultdict = defaultdict(
             lambda: {"satisfied": 0, "unsatisfied": 0}
         )
+        self._sampled_from_all_strategies_elements_message: Optional[
+            tuple[str, object]
+        ] = None
 
         self.expected_exception: Optional[BaseException] = None
         self.expected_traceback: Optional[str] = None
@@ -991,6 +994,8 @@ def draw_string(
     ) -> str:
         assert forced is None or min_size <= len(forced) <= max_size
         assert min_size >= 0
+        if len(intervals) == 0:
+            assert min_size == 0
 
         kwargs: StringKWargs = self._pooled_kwargs(
             "string",

hypothesis-python/src/hypothesis/internal/conjecture/providers.py

@@ -370,7 +370,9 @@ def draw_float(
                     clamped = result  # pragma: no cover
                 else:
                     clamped = clamper(result)
-                if clamped != result and not (math.isnan(result) and allow_nan):
+                if float_to_int(clamped) != float_to_int(result) and not (
+                    math.isnan(result) and allow_nan
+                ):
                     result = clamped
             else:
                 result = nasty_floats[i - 1]
@@ -386,6 +388,9 @@ def draw_string(
         assert self._cd is not None
         assert self._cd._random is not None
 
+        if len(intervals) == 0:
+            return ""
+
         average_size = min(
             max(min_size * 2, min_size + 5),
             0.5 * (min_size + max_size),

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

@@ -16,22 +16,24 @@
 from functools import partial
 from inspect import getframeinfo
 from pathlib import Path
-from typing import NamedTuple, Optional
+from types import ModuleType
+from typing import Callable, NamedTuple, Optional
 
 import hypothesis
 from hypothesis.errors import _Trimmable
 from hypothesis.internal.compat import BaseExceptionGroup
 from hypothesis.utils.dynamicvariables import DynamicVariable
 
 
-def belongs_to(package):
-    if not hasattr(package, "__file__"):  # pragma: no cover
+def belongs_to(package: ModuleType) -> Callable[[str], bool]:
+    if getattr(package, "__file__", None) is None:  # pragma: no cover
         return lambda filepath: False
 
+    assert package.__file__ is not None
     root = Path(package.__file__).resolve().parent
-    cache = {str: {}, bytes: {}}
+    cache: dict[type, dict[str, bool]] = {str: {}, bytes: {}}
 
-    def accept(filepath):
+    def accept(filepath: str) -> bool:
         ftype = type(filepath)
         try:
             return cache[ftype][filepath]

hypothesis-python/src/hypothesis/stateful.py

@@ -22,7 +22,7 @@
 from functools import lru_cache
 from io import StringIO
 from time import perf_counter
-from typing import Any, Callable, ClassVar, Optional, Union, overload
+from typing import Any, Callable, ClassVar, Optional, TypeVar, Union, overload
 from unittest import TestCase
 
 import attr
@@ -54,13 +54,13 @@
 from hypothesis.strategies._internal.featureflags import FeatureStrategy
 from hypothesis.strategies._internal.strategies import (
     Ex,
-    Ex_Inv,
     OneOfStrategy,
     SearchStrategy,
     check_strategy,
 )
 from hypothesis.vendor.pretty import RepresentationPrinter
 
+T = TypeVar("T")
 STATE_MACHINE_RUN_LABEL = cu.calc_label_from_name("another state machine step")
 SHOULD_CONTINUE_LABEL = cu.calc_label_from_name("should we continue drawing")
 
@@ -591,9 +591,7 @@ def __iter__(self):
         return iter(self.values)
 
 
-# We need to use an invariant typevar here to avoid a mypy error, as covariant
-# typevars cannot be used as parameters.
-def multiple(*args: Ex_Inv) -> MultipleResults[Ex_Inv]:
+def multiple(*args: T) -> MultipleResults[T]:
     """This function can be used to pass multiple results to the target(s) of
     a rule. Just use ``return multiple(result1, result2, ...)`` in your rule.
 

hypothesis-python/src/hypothesis/strategies/_internal/core.py

@@ -127,7 +127,6 @@
 from hypothesis.strategies._internal.shared import SharedStrategy
 from hypothesis.strategies._internal.strategies import (
     Ex,
-    Ex_Inv,
     SampledFromStrategy,
     T,
     one_of,
@@ -360,16 +359,20 @@ def lists(
 
         # UniqueSampledListStrategy offers a substantial performance improvement for
         # unique arrays with few possible elements, e.g. of eight-bit integer types.
+
+        # all of these type: ignores are for a mypy bug, which narrows `elements`
+        # to Never. https://github.com/python/mypy/issues/16494
         if (
             isinstance(elements, IntegersStrategy)
-            and None not in (elements.start, elements.end)
-            and (elements.end - elements.start) <= 255
+            and elements.start is not None  # type: ignore
+            and elements.end is not None  # type: ignore
+            and (elements.end - elements.start) <= 255  # type: ignore
         ):
             elements = SampledFromStrategy(
-                sorted(range(elements.start, elements.end + 1), key=abs)
-                if elements.end < 0 or elements.start > 0
-                else list(range(elements.end + 1))
-                + list(range(-1, elements.start - 1, -1))
+                sorted(range(elements.start, elements.end + 1), key=abs)  # type: ignore
+                if elements.end < 0 or elements.start > 0  # type: ignore
+                else list(range(elements.end + 1))  # type: ignore
+                + list(range(-1, elements.start - 1, -1))  # type: ignore
             )
 
         if isinstance(elements, SampledFromStrategy):
@@ -1106,7 +1109,7 @@ def builds(
 
 @cacheable
 @defines_strategy(never_lazy=True)
-def from_type(thing: type[Ex_Inv]) -> SearchStrategy[Ex_Inv]:
+def from_type(thing: type[T]) -> SearchStrategy[T]:
     """Looks up the appropriate search strategy for the given type.
 
     ``from_type`` is used internally to fill in missing arguments to

hypothesis-python/src/hypothesis/strategies/_internal/numbers.py

@@ -47,8 +47,8 @@
 Real = Union[int, float, Fraction, Decimal]
 
 
-class IntegersStrategy(SearchStrategy):
-    def __init__(self, start, end):
+class IntegersStrategy(SearchStrategy[int]):
+    def __init__(self, start: Optional[int], end: Optional[int]) -> None:
         assert isinstance(start, int) or start is None
         assert isinstance(end, int) or end is None
         assert start is None or end is None or start <= end