Initial support for stateful testing

docs-src/changelog.md

@@ -2,6 +2,10 @@
 HypoFuzz uses [calendar-based versioning](https://calver.org/), with a
 `YY-MM-patch` format.
 
+## 25.02.2
+
+Initial support for [stateful tests](https://hypothesis.readthedocs.io/en/latest/stateful.html).
+
 ## 25.02.1
 
 Use a new mutator based on the typed choice sequence (https://github.com/HypothesisWorks/hypothesis/issues/3921), bringing back compatibility with new Hypothesis versions.

src/hypofuzz/__init__.py

@@ -1,4 +1,4 @@
 """Adaptive fuzzing for property-based tests using Hypothesis."""
 
-__version__ = "25.02.1"
+__version__ = "25.02.2"
 __all__: list = []

src/hypofuzz/interface.py

@@ -4,20 +4,22 @@
 import sys
 from collections.abc import Iterable
 from contextlib import redirect_stdout
-from functools import partial
 from inspect import signature
 from typing import TYPE_CHECKING, get_type_hints
 
 import pytest
 from _pytest.nodes import Item, Node
 from _pytest.skipping import evaluate_condition
-from hypothesis.stateful import RuleBasedStateMachine, run_state_machine_as_test
+from hypothesis.stateful import get_state_machine_test
+from packaging import version
 
 if TYPE_CHECKING:
     # We have to defer imports to within functions here, because this module
     # is a Hypothesis entry point and is thus imported earlier than the others.
     from .hy import FuzzProcess
 
+pytest8 = version.parse(pytest.__version__) >= version.parse("8.0.0")
+
 
 def has_true_skipif(item: Item) -> bool:
     # multiple @skipif decorators are treated as an OR.
@@ -77,6 +79,7 @@ def pytest_collection_finish(self, session: pytest.Session) -> None:
             # values directly, so we can pass them as extra kwargs to FuzzProcess.
             params = item.callspec.params if hasattr(item, "callspec") else {}
             param_names = set(params)
+            extra_kw = params
 
             # Skip any test which:
             # - directly requests a non autouse fixture, or
@@ -101,16 +104,32 @@ def pytest_collection_finish(self, session: pytest.Session) -> None:
                     flush=True,
                 )
                 continue
-
             # Wrap it up in a FuzzTarget and we're done!
             try:
-                # Skip state-machine classes, since they're not
-                if isinstance(item.obj, RuleBasedStateMachine.TestCase):
-                    target = partial(run_state_machine_as_test, item.obj)
+                if hasattr(item.obj, "_hypothesis_state_machine_class"):
+                    assert (
+                        extra_kw == {}
+                    ), "Not possible for RuleBasedStateMachine.TestCase to be parametrized"
+                    runTest = item.obj
+                    StateMachineClass = runTest._hypothesis_state_machine_class
+                    target = get_state_machine_test(  # type: ignore
+                        StateMachineClass,
+                        # runTest is a function, not a bound method, under pyest7.
+                        # I wonder if something about TestCase instantiation order
+                        # changed in pytest 8? Either way, we can't access
+                        # __self__.settings under pytest 7.
+                        #
+                        # I am going to call this an acceptably rare bug for now,
+                        # because it should only manifest if the user sets a custom
+                        # database on a stateful test under pytest 7 (all non-db
+                        # settings are ignored by hypofuzz).
+                        settings=runTest.__self__.settings if pytest8 else None,
+                    )
+                    extra_kw = {"factory": StateMachineClass}
                 else:
                     target = item.obj
                 fuzz = FuzzProcess.from_hypothesis_test(
-                    target, nodeid=item.nodeid, extra_kw=params
+                    target, nodeid=item.nodeid, extra_kw=extra_kw
                 )
                 self.fuzz_targets.append(fuzz)
             except Exception as err:

tests/test_collection.py

@@ -16,6 +16,7 @@ def collect(code: str) -> list[FuzzProcess]:
             """
             import pytest
             from hypothesis import given, strategies as st
+            from hypothesis.stateful import RuleBasedStateMachine, Bundle, initialize, rule
             """
         )
         + "\n"
@@ -152,3 +153,28 @@ def test_a(n):
         pass
     """
     assert not collect_names(code)
+
+
+def test_collects_stateful_test():
+    code = """
+    names = st.text(min_size=1).filter(lambda x: "/" not in x)
+
+    class NumberModifier(RuleBasedStateMachine):
+        folders = Bundle("folders")
+        files = Bundle("files")
+
+        @initialize(target=folders)
+        def init_folders(self):
+            return "/"
+
+        @rule(target=folders, parent=folders, name=names)
+        def create_folder(self, parent, name):
+            return f"{parent}/{name}"
+
+        @rule(target=files, parent=folders, name=names)
+        def create_file(self, parent, name):
+            return f"{parent}/{name}"
+
+    NumberModifierTest = NumberModifier.TestCase
+    """
+    assert collect_names(code) == {"run_state_machine"}