Merge pull request #3971 from Zac-HD/composite-overload-warning

Don't warn on typing overloads for a composite function

Author: Zac-HD

hypothesis-python/RELEASE.rst

@@ -0,0 +1,5 @@
+RELEASE_TYPE: patch
+
+This patch turns off a warning for functions decorated with
+:func:`typing.overload` and then :func:`~hypothesis.strategies.composite`,
+although only in that order (:issue:`3970`).

hypothesis-python/docs/strategies.rst

@@ -57,6 +57,12 @@ Or some other custom integration, such as a :ref:`"hypothesis" entry point <entr
 Other cool things
 -----------------
 
+`Tyche <https://marketplace.visualstudio.com/items?itemName=HarrisonGoldstein.tyche>`__
+(`source <https://github.com/tyche-pbt>`__) is a VSCode extension which provides live
+insights into your property-based tests, including the distribution of generated inputs
+and the resulting code coverage.  You can `read the research paper here
+<https://harrisongoldste.in/papers/uist23.pdf>`__.
+
 :pypi:`schemathesis` is a tool for testing web applications built with `Open API / Swagger specifications <https://swagger.io/>`_.
 It reads the schema and generates test cases which will ensure that the application is compliant with its schema.
 The application under test could be written in any language, the only thing you need is a valid API schema in a supported format.

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

@@ -48,6 +48,7 @@ def pretty_file_name(f):
 
 
 IN_COVERAGE_TESTS = os.getenv("HYPOTHESIS_INTERNAL_COVERAGE") == "true"
+description_stack = []
 
 
 if IN_COVERAGE_TESTS:
@@ -64,8 +65,6 @@ def record_branch(name, value):
         with open(f"branch-check-{os.getpid()}", mode="a", encoding="utf-8") as log:
             log.write(json.dumps({"name": name, "value": value}) + "\n")
 
-    description_stack = []
-
     @contextmanager
     def check_block(name, depth):
         # We add an extra two callers to the stack: One for the contextmanager

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

@@ -83,6 +83,7 @@
     is_typed_named_tuple,
 )
 from hypothesis.internal.conjecture.utils import calc_label_from_cls, check_sample
+from hypothesis.internal.coverage import IN_COVERAGE_TESTS, description_stack
 from hypothesis.internal.entropy import get_seeder_and_restorer
 from hypothesis.internal.floats import float_of
 from hypothesis.internal.observability import TESTCASE_CALLBACKS
@@ -1757,8 +1758,22 @@ def __init__(self, definition, args, kwargs):
         self.args = args
         self.kwargs = kwargs
 
-    def do_draw(self, data):
-        return self.definition(data.draw, *self.args, **self.kwargs)
+    if IN_COVERAGE_TESTS:
+        # We do a bit of a dance here to ensure that whatever 'outer' description
+        # stack we might have, doesn't affect the validation code internal to the
+        # strategy we're drawing from.  Otherwise, we'd get flaky fails like #3968.
+        def do_draw(self, data):
+            prev = description_stack[:]
+            try:
+                description_stack.clear()
+                return self.definition(data.draw, *self.args, **self.kwargs)
+            finally:
+                description_stack[:] = prev
+
+    else:  # pragma: no cover
+
+        def do_draw(self, data):
+            return self.definition(data.draw, *self.args, **self.kwargs)
 
     def calc_label(self):
         return calc_label_from_cls(self.definition)
@@ -1810,7 +1825,7 @@ def _composite(f):
         )
     if params[0].default is not sig.empty:
         raise InvalidArgument("A default value for initial argument will never be used")
-    if not is_first_param_referenced_in_function(f):
+    if not (f is typing._overload_dummy or is_first_param_referenced_in_function(f)):
         note_deprecation(
             "There is no reason to use @st.composite on a function which "
             "does not call the provided draw() function internally.",

hypothesis-python/tests/cover/test_composite.py

@@ -9,6 +9,7 @@
 # obtain one at https://mozilla.org/MPL/2.0/.
 
 import sys
+import typing
 
 import pytest
 
@@ -204,3 +205,18 @@ def my_integers(draw: st.DrawFn) -> st.SearchStrategy[int]:
 
     assert len(w.list) == 1
     assert w.list[0].filename == __file__  # check stacklevel points to user code
+
+
+def test_composite_allows_overload_without_draw():
+    # See https://github.com/HypothesisWorks/hypothesis/issues/3970
+    @st.composite
+    @typing.overload
+    def overloaded(draw: st.DrawFn, *, x: int) -> typing.Literal[True]: ...
+
+    @st.composite
+    @typing.overload
+    def overloaded(draw: st.DrawFn, *, x: str) -> typing.Literal[False]: ...
+
+    @st.composite
+    def overloaded(draw: st.DrawFn, *, x: typing.Union[int, str]) -> bool:
+        return draw(st.just(isinstance(x, int)))