address review

Author: tybug

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

@@ -840,20 +840,16 @@ def on_observation(observation: Observation) -> None:
             if not self._switch_to_hypothesis_provider:
                 self.provider.on_observation(observation)
 
-        # adding this callback enables observability. Use a nullcontext
-        # if the backend won't use observability.
-        return (
-            with_observation_callback(on_observation)
-            if (
-                self.settings.backend != "hypothesis"
-                # only for lifetime = "test_function" providers (guaranteed
-                # by this isinstance check)
-                and isinstance(self.provider, PrimitiveProvider)
-                # and the provider opted-in to observations
-                and self.provider.add_observability_callback
-            )
-            else nullcontext()
-        )
+        if (
+            self.settings.backend != "hypothesis"
+            # only for lifetime = "test_function" providers (guaranteed
+            # by this isinstance check)
+            and isinstance(self.provider, PrimitiveProvider)
+            # and the provider opted-in to observations
+            and self.provider.add_observability_callback
+        ):
+            return with_observation_callback(on_observation)
+        return nullcontext()
 
     def run(self) -> None:
         with (

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

@@ -587,10 +587,6 @@ def on_observation(self, observation: TestCaseObservation) -> None:  # noqa: B02
         during |Phase.reuse| or |Phase.shrink|, or because Hypothesis switched
         to the standard Hypothesis backend after this backend raised too many
         |BackendCannotProceed| exceptions.
-
-        By default, observability will not be enabled for backends which do not
-        override this method. By overriding this method, any test which sets
-        |settings.backend| to this provider will automatically enable observability.
         """
 
     def span_start(self, label: int, /) -> None:  # noqa: B027  # non-abstract noop

hypothesis-python/tests/conjecture/test_alt_backend.py

@@ -741,23 +741,21 @@ def on_observation(self, observation: Observation) -> None:
         self.expected = "per_test_case_context_manager"
 
 
+@temp_register_backend("observation", ObservationProvider)
 def test_on_observation_alternates():
-    with temp_register_backend("observation", ObservationProvider):
+    @given(st.integers())
+    @settings(backend="observation")
+    def f(n):
+        pass
 
-        @given(st.integers())
-        @settings(backend="observation")
-        def f(n):
-            pass
-
-        f()
+    f()
 
 
+@temp_register_backend("observation", TrivialProvider)
 def test_on_observation_no_override():
-    with temp_register_backend("observation", TrivialProvider):
+    @given(st.integers())
+    @settings(backend="observation")
+    def f(n):
+        assert TESTCASE_CALLBACKS == []
 
-        @given(st.integers())
-        @settings(backend="observation")
-        def f(n):
-            assert TESTCASE_CALLBACKS == []
-
-        f()
+    f()