respect forced for ir tree nodes

Author: tybug

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

@@ -1909,10 +1909,11 @@ def draw_integer(
         )
 
         if self.ir_tree_nodes is not None and observe:
-            node = self._pop_ir_tree_node("integer", kwargs, forced=forced)
-            assert isinstance(node.value, int)
-            forced = node.value
-            fake_forced = not node.was_forced
+            node = self._pop_ir_tree_node("integer", kwargs)
+            if forced is None:
+                assert isinstance(node.value, int)
+                forced = node.value
+                fake_forced = True
 
         value = self.provider.draw_integer(
             **kwargs, forced=forced, fake_forced=fake_forced
@@ -1965,10 +1966,11 @@ def draw_float(
         )
 
         if self.ir_tree_nodes is not None and observe:
-            node = self._pop_ir_tree_node("float", kwargs, forced=forced)
-            assert isinstance(node.value, float)
-            forced = node.value
-            fake_forced = not node.was_forced
+            node = self._pop_ir_tree_node("float", kwargs)
+            if forced is None:
+                assert isinstance(node.value, float)
+                forced = node.value
+                fake_forced = True
 
         value = self.provider.draw_float(
             **kwargs, forced=forced, fake_forced=fake_forced
@@ -2006,10 +2008,11 @@ def draw_string(
             },
         )
         if self.ir_tree_nodes is not None and observe:
-            node = self._pop_ir_tree_node("string", kwargs, forced=forced)
-            assert isinstance(node.value, str)
-            forced = node.value
-            fake_forced = not node.was_forced
+            node = self._pop_ir_tree_node("string", kwargs)
+            if forced is None:
+                assert isinstance(node.value, str)
+                forced = node.value
+                fake_forced = True
 
         value = self.provider.draw_string(
             **kwargs, forced=forced, fake_forced=fake_forced
@@ -2041,10 +2044,11 @@ def draw_bytes(
         kwargs: BytesKWargs = self._pooled_kwargs("bytes", {"size": size})
 
         if self.ir_tree_nodes is not None and observe:
-            node = self._pop_ir_tree_node("bytes", kwargs, forced=forced)
-            assert isinstance(node.value, bytes)
-            forced = node.value
-            fake_forced = not node.was_forced
+            node = self._pop_ir_tree_node("bytes", kwargs)
+            if forced is None:
+                assert isinstance(node.value, bytes)
+                forced = node.value
+                fake_forced = True
 
         value = self.provider.draw_bytes(
             **kwargs, forced=forced, fake_forced=fake_forced
@@ -2082,10 +2086,11 @@ def draw_boolean(
         kwargs: BooleanKWargs = self._pooled_kwargs("boolean", {"p": p})
 
         if self.ir_tree_nodes is not None and observe:
-            node = self._pop_ir_tree_node("boolean", kwargs, forced=forced)
-            assert isinstance(node.value, bool)
-            forced = node.value
-            fake_forced = not node.was_forced
+            node = self._pop_ir_tree_node("boolean", kwargs)
+            if forced is None:
+                assert isinstance(node.value, bool)
+                forced = node.value
+                fake_forced = True
 
         value = self.provider.draw_boolean(
             **kwargs, forced=forced, fake_forced=fake_forced
@@ -2122,9 +2127,7 @@ def _pooled_kwargs(self, ir_type, kwargs):
             POOLED_KWARGS_CACHE[key] = kwargs
             return kwargs
 
-    def _pop_ir_tree_node(
-        self, ir_type: IRTypeName, kwargs: IRKWargsType, *, forced: Optional[IRType]
-    ) -> IRNode:
+    def _pop_ir_tree_node(self, ir_type: IRTypeName, kwargs: IRKWargsType) -> IRNode:
         assert self.ir_tree_nodes is not None
 
         if self.ir_tree_nodes == []:
@@ -2151,32 +2154,6 @@ def _pop_ir_tree_node(
         if not ir_value_permitted(node.value, node.ir_type, kwargs):
             self.mark_invalid()  # pragma: no cover  # FIXME @tybug
 
-        if forced is not None:
-            # if we expected a forced node but are instead returning a non-forced
-            # node, something has gone terribly wrong. If we allowed this combination,
-            # we risk violating core invariants that rely on forced draws being,
-            # well, forced to a particular value.
-            #
-            # In particular, this can manifest while shrinking. Consider the tree
-            #   [boolean True [forced] {"p": 0.5}]
-            #   [boolean False {"p": 0.5}]
-            #
-            # and the shrinker tries to reorder these to
-            #   [boolean False {"p": 0.5}]
-            #   [boolean True [forced] {"p": 0.5}].
-            #
-            # However, maybe we got lucky and the non-forced node is returning
-            # the same value that was expected from the forced draw. We lucked
-            # into an aligned tree in this case and can let it slide.
-            if not node.was_forced and not ir_value_equal(ir_type, forced, node.value):
-                self.mark_invalid()
-
-            # similarly, if we expected a forced node with a certain value, and
-            # are returning a forced node with a different value, this is an
-            # equally bad misalignment.
-            if node.was_forced and not ir_value_equal(ir_type, forced, node.value):
-                self.mark_invalid()
-
         return node
 
     def as_result(self) -> Union[ConjectureResult, _Overrun]:

hypothesis-python/tests/conjecture/test_ir.py

@@ -386,7 +386,7 @@ def test_data_with_misaligned_ir_tree_is_invalid(data):
 
 
 @given(st.data())
-def test_data_with_changed_was_forced_is_invalid(data):
+def test_data_with_changed_was_forced(data):
     # we had a normal node and then tried to draw a different forced value from it.
     # ir tree: v1 [was_forced=False]
     # drawing:    [forced=v2]
@@ -398,18 +398,19 @@ def test_data_with_changed_was_forced_is_invalid(data):
     kwargs["forced"] = draw_value(node.ir_type, node.kwargs)
     assume(not ir_value_equal(node.ir_type, kwargs["forced"], node.value))
 
-    with pytest.raises(StopTest):
-        draw_func(**kwargs)
-
-    assert data.status is Status.INVALID
+    assert ir_value_equal(node.ir_type, draw_func(**kwargs), kwargs["forced"])
 
 
 @given(st.data())
 @settings(suppress_health_check=[HealthCheck.too_slow])
-def test_data_with_changed_forced_value_is_invalid(data):
+def test_data_with_changed_forced_value(data):
     # we had a forced node and then tried to draw a different forced value from it.
     # ir tree: v1 [was_forced=True]
     # drawing:    [forced=v2]
+    #
+    # This is actually fine; we'll just ignore the forced node (v1) and return
+    # what the draw expects (v2).
+
     node = data.draw(ir_nodes(was_forced=True))
     data = ConjectureData.for_ir_tree([node])
 
@@ -418,10 +419,7 @@ def test_data_with_changed_forced_value_is_invalid(data):
     kwargs["forced"] = draw_value(node.ir_type, node.kwargs)
     assume(not ir_value_equal(node.ir_type, kwargs["forced"], node.value))
 
-    with pytest.raises(StopTest):
-        draw_func(**kwargs)
-
-    assert data.status is Status.INVALID
+    assert ir_value_equal(node.ir_type, draw_func(**kwargs), kwargs["forced"])
 
 
 @given(st.data())
@@ -436,7 +434,7 @@ def test_data_with_same_forced_value_is_valid(data):
 
     kwargs = deepcopy(node.kwargs)
     kwargs["forced"] = node.value
-    draw_func(**kwargs)
+    assert ir_value_equal(node.ir_type, draw_func(**kwargs), kwargs["forced"])
 
 
 @given(ir_types_and_kwargs())