narrow the severity and cases for alternate API use suggestion; close #3819

Revised per suggestion here: #3820 (comment)

Author: vreuter

hypothesis-python/RELEASE.rst

@@ -1,5 +1,4 @@
 RELEASE_TYPE: patch
 
-This patch causes a warning to be issued when :func:`~hypothesis.strategies.sampled_from` is given a nonempty collection of all strategy values as the argument to its `strategies` parameter (:issue:`3819``).
+This patch causes a [note to be included](https://peps.python.org/pep-0678/) when :func:`~hypothesis.strategies.sampled_from` is given a nonempty collection of all strategy values _and_ the `given`-decorated test fails with a `TypeError` (:issue:`3819``).
 This is because such a call is suggestive of intent to instead use :func:`~hypothesis.strategies.one_of`.
-This closes 

hypothesis-python/src/hypothesis/core.py

@@ -1585,6 +1585,20 @@ def wrapped_test(*arguments, **kwargs):
                         if isinstance(e, BaseExceptionGroup)
                         else get_trimmed_traceback()
                     )
+                    if (
+                        isinstance(e, TypeError)
+                        and "SearchStrategy" in str(e)
+                        and any(
+                            getattr(
+                                s, "sampling_is_from_a_collection_of_strategies", False
+                            )
+                            for s in given_kwargs.values()
+                        )
+                    ):
+                        add_note(
+                            e,
+                            "sample_from was given a collection of strategies; was one_of intended?",
+                        )
                     raise the_error_hypothesis_found
 
             if not (ran_explicit_examples or state.ever_executed):

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

@@ -214,11 +214,6 @@ def sampled_from(
                 "so maybe you tried to write an enum as if it was a dataclass?"
             )
         raise InvalidArgument("Cannot sample from a length-zero sequence.")
-    elif all(isinstance(x, SearchStrategy) for x in values):
-        warnings.warn(
-            "sample_from was given a collection of strategies; was one_of intended?",
-            stacklevel=1,
-        )
     if len(values) == 1:
         return just(values[0])
     try:

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

@@ -477,6 +477,9 @@ def __init__(self, elements, repr_=None, transformations=()):
         super().__init__()
         self.elements = cu.check_sample(elements, "sampled_from")
         assert self.elements
+        self.sampling_is_from_a_collection_of_strategies = all(
+            isinstance(x, SearchStrategy) for x in self.elements
+        )
         self.repr_ = repr_
         self._transformations = transformations
 

hypothesis-python/tests/cover/test_lookup.py

@@ -311,10 +311,8 @@ class Baz(Foo):
 
 
 @pytest.mark.parametrize(
-    "var,expected,exp_warn",
+    "var,expected",
     [
-        # Expect a warning exactly when the type constraint/bound should trigger
-        # passing a strategy to sampled_from.
         (typing.TypeVar("V"), object),
         (typing.TypeVar("V", bound=int), int),
         (typing.TypeVar("V", bound=Foo), (Bar, Baz)),

hypothesis-python/tests/cover/test_sampled_from.py

@@ -192,11 +192,113 @@ def test_suggests_elements_instead_of_annotations():
         st.sampled_from(AnnotationsInsteadOfElements).example()
 
 
-@pytest.mark.parametrize("wrap", [list, tuple])
-def test_warns_when_given_entirely_strategies_as_elements(wrap):
-    elements = wrap([st.booleans(), st.decimals(), st.integers(), st.text()])
-    with pytest.warns(
-        UserWarning,
-        match="sample_from was given a collection of strategies; was one_of intended?",
+class TestErrorNoteBehavior3819:
+    elements = (st.booleans(), st.decimals(), st.integers(), st.text())
+
+    def execute_expecting_error(test_func):
+        with pytest.raises(TypeError) as err_ctx:
+            test_func()
+        obs_notes = getattr(err_ctx.value, "__notes__", [])
+        assert obs_notes[-1] == exp_msg
+
+    @staticmethod
+    @given(st.sampled_from(elements))
+    def args_with_type_error_with_message_substring(_):
+        raise TypeError("SearchStrategy")
+
+    @staticmethod
+    @given(all_strat_sample=st.sampled_from(elements))
+    def kwargs_with_type_error_with_message_substring(all_strat_sample):
+        raise TypeError("SearchStrategy")
+
+    @staticmethod
+    @given(st.sampled_from(elements))
+    def args_with_type_error_without_message_substring(_):
+        raise TypeError("Substring not in message!")
+
+    @staticmethod
+    @given(st.sampled_from(elements))
+    def kwargs_with_type_error_without_message_substring(_):
+        raise TypeError("Substring not in message!")
+
+    @staticmethod
+    @given(st.sampled_from(elements))
+    def type_error_but_not_all_strategies_args(_):
+        raise TypeError("SearchStrategy, but should not trigger note addition!")
+
+    @staticmethod
+    @given(all_strat_sample=st.sampled_from(elements))
+    def type_error_but_not_all_strategies_kwargs(all_strat_sample):
+        raise TypeError("SearchStrategy, but should not trigger note addition!")
+
+    @staticmethod
+    @given(st.sampled_from(elements))
+    def non_type_error_args(_):
+        raise Exception("SearchStrategy, but should not trigger note addition!")
+
+    @staticmethod
+    @given(all_strat_sample=st.sampled_from(elements))
+    def non_type_error_kwargs(all_strat_sample):
+        raise Exception("SearchStrategy, but should not trigger note addition!")
+
+    @staticmethod
+    @given(st.sampled_from(elements))
+    def args_without_error(_):
+        return
+
+    @staticmethod
+    @given(all_strat_sample=st.sampled_from(elements))
+    def kwargs_without_error(all_strat_sample):
+        return
+
+    @pytest.mark.parametrize(
+        ["func_to_call", "exp_err_cls", "should_exp_msg"],
+        [
+            (f, TypeError, True)
+            for f in (
+                args_with_type_error_with_message_substring,
+                kwargs_with_type_error_with_message_substring,
+            )
+        ]
+        + [
+            (f, TypeError, False)
+            for f in (
+                args_with_type_error_without_message_substring,
+                kwargs_with_type_error_without_message_substring,
+            )
+        ]
+        + [
+            (f, TypeError, False)
+            for f in (
+                type_error_but_not_all_strategies_args,
+                type_error_but_not_all_strategies_kwargs,
+            )
+        ]
+        + [(f, Exception, False) for f in (non_type_error_args, non_type_error_kwargs)]
+        + [(f, None, False) for f in (args_without_error, kwargs_without_error)],
+    )
+    def test_error_appropriate_error_note_3819(
+        self, func_to_call, exp_err_cls, should_exp_msg
     ):
-        st.sampled_from(elements)
+        if exp_err_cls is None:
+            try:
+                func_to_call()
+            except BaseException as e:
+                pytest.fail(f"Expected call to succeed but got error: {e}")
+            else:
+                assert True
+        else:
+            with pytest.raises(Exception) as err_ctx:
+                func_to_call()
+            err = err_ctx.value
+            assert type(err) is exp_err_cls
+            notes = getattr(err, "__notes__", [])
+            msg_in_notes = (
+                "sample_from was given a collection of strategies; was one_of intended?"
+                in notes
+            )
+            assert (
+                should_exp_msg
+                and msg_in_notes
+                or (not should_exp_msg and not should_exp_msg)
+            )