Print original bundle variable names in stateful mode

hypothesis-python/RELEASE.rst

@@ -0,0 +1,4 @@
+RELEASE_TYPE: patch
+
+This patch adjusts the printing of bundle values to correspond
+with their names when using stateful testing.

hypothesis-python/src/hypothesis/stateful.py

@@ -15,7 +15,7 @@
 Notably, the set of steps available at any point may depend on the
 execution to date.
 """
-
+import collections
 import inspect
 from copy import copy
 from functools import lru_cache
@@ -268,7 +268,8 @@ def __init__(self) -> None:
         if not self.rules():
             raise InvalidDefinition(f"Type {type(self).__name__} defines no rules")
         self.bundles: Dict[str, list] = {}
-        self.name_counter = 1
+        self.names_counters: collections.Counter = collections.Counter()
+        self.names_list: list[str] = []
         self.names_to_values: Dict[str, Any] = {}
         self.__stream = StringIO()
         self.__printer = RepresentationPrinter(
@@ -301,15 +302,16 @@ def _pretty_print(self, value):
     def __repr__(self):
         return f"{type(self).__name__}({nicerepr(self.bundles)})"
 
-    def _new_name(self):
-        result = f"v{self.name_counter}"
-        self.name_counter += 1
+    def _new_name(self, target):
+        result = f"{target}_{self.names_counters[target]}"
+        self.names_counters[target] += 1
+        self.names_list.append(result)
         return result
 
     def _last_names(self, n):
-        assert self.name_counter > n
-        count = self.name_counter
-        return [f"v{i}" for i in range(count - n, count)]
+        len_ = len(self.names_list)
+        assert len_ >= n
+        return self.names_list[len_ - n :]
 
     def bundle(self, name):
         return self.bundles.setdefault(name, [])
@@ -364,20 +366,23 @@ def _repr_step(self, rule, data, result):
                 if len(result.values) == 1:
                     output_assignment = f"({self._last_names(1)[0]},) = "
                 elif result.values:
-                    output_names = self._last_names(len(result.values))
+                    number_of_last_names = len(rule.targets) * len(result.values)
+                    output_names = self._last_names(number_of_last_names)
                     output_assignment = ", ".join(output_names) + " = "
             else:
                 output_assignment = self._last_names(1)[0] + " = "
         args = ", ".join("%s=%s" % kv for kv in data.items())
         return f"{output_assignment}state.{rule.function.__name__}({args})"
 
     def _add_result_to_targets(self, targets, result):
-        name = self._new_name()
-        self.__printer.singleton_pprinters.setdefault(
-            id(result), lambda obj, p, cycle: p.text(name)
-        )
-        self.names_to_values[name] = result
         for target in targets:
+            name = self._new_name(target)
+
+            def printer(obj, p, cycle):
+                return p.text(name)
+
+            self.__printer.singleton_pprinters.setdefault(id(result), printer)
+            self.names_to_values[name] = result
             self.bundles.setdefault(target, []).append(VarReference(name))
 
     def check_invariants(self, settings, output, runtimes):

hypothesis-python/tests/cover/test_stateful.py

@@ -225,12 +225,12 @@ def fail_fast(self):
     assignment_line = err.value.__notes__[2]
     # 'populate_bundle()' returns 2 values, so should be
     # expanded to 2 variables.
-    assert assignment_line == "v1, v2 = state.populate_bundle()"
+    assert assignment_line == "b_0, b_1 = state.populate_bundle()"
 
     # Make sure MultipleResult is iterable so the printed code is valid.
     # See https://github.com/HypothesisWorks/hypothesis/issues/2311
     state = ProducesMultiple()
-    v1, v2 = state.populate_bundle()
+    b_0, b_1 = state.populate_bundle()
     with raises(AssertionError):
         state.fail_fast()
 
@@ -252,7 +252,7 @@ def fail_fast(self, b):
         run_state_machine_as_test(ProducesMultiple)
 
     assignment_line = err.value.__notes__[2]
-    assert assignment_line == "(v1,) = state.populate_bundle()"
+    assert assignment_line == "(b_0,) = state.populate_bundle()"
 
     state = ProducesMultiple()
     (v1,) = state.populate_bundle()
@@ -797,9 +797,9 @@ def fail(self, source):
     result = "\n".join(err.value.__notes__)
     for m in ["create", "transfer", "fail"]:
         assert result.count("state." + m) == 1
-    assert "v1 = state.create()" in result
-    assert "v2 = state.transfer(source=v1)" in result
-    assert "state.fail(source=v2)" in result
+    assert "b1_0 = state.create()" in result
+    assert "b2_0 = state.transfer(source=b1_0)" in result
+    assert "state.fail(source=b2_0)" in result
 
 
 def test_initialize_rule():
@@ -845,7 +845,7 @@ class WithInitializeBundleRules(RuleBasedStateMachine):
 
         @initialize(target=a, dep=just("dep"))
         def initialize_a(self, dep):
-            return f"a v1 with ({dep})"
+            return f"a a_0 with ({dep})"
 
         @rule(param=a)
         def fail_fast(self, param):
@@ -861,8 +861,8 @@ def fail_fast(self, param):
         == """
 Falsifying example:
 state = WithInitializeBundleRules()
-v1 = state.initialize_a(dep='dep')
-state.fail_fast(param=v1)
+a_0 = state.initialize_a(dep='dep')
+state.fail_fast(param=a_0)
 state.teardown()
 """.strip()
     )
@@ -1087,8 +1087,8 @@ def mostly_fails(self, d):
 
     with pytest.raises(AssertionError) as err:
         run_state_machine_as_test(TrickyPrintingMachine)
-    assert "v1 = state.init_data(value=0)" in err.value.__notes__
-    assert "v1 = state.init_data(value=v1)" not in err.value.__notes__
+    assert "data_0 = state.init_data(value=0)" in err.value.__notes__
+    assert "data_0 = state.init_data(value=data_0)" not in err.value.__notes__
 
 
 class TrickyInitMachine(RuleBasedStateMachine):
@@ -1182,3 +1182,109 @@ def test_fails_on_settings_class_attribute():
         match="Assigning .+ as a class attribute does nothing",
     ):
         run_state_machine_as_test(ErrorsOnClassAttributeSettings)
+
+
+def test_single_target_multiple():
+    class Machine(RuleBasedStateMachine):
+        a = Bundle("a")
+
+        @initialize(target=a)
+        def initialize(self):
+            return multiple("ret1", "ret2", "ret3")
+
+        @rule(param=a)
+        def fail_fast(self, param):
+            raise AssertionError
+
+    Machine.TestCase.settings = NO_BLOB_SETTINGS
+    with pytest.raises(AssertionError) as err:
+        run_state_machine_as_test(Machine)
+
+    result = "\n".join(err.value.__notes__)
+    assert (
+        result
+        == """
+Falsifying example:
+state = Machine()
+a_0, a_1, a_2 = state.initialize()
+state.fail_fast(param=a_2)
+state.teardown()
+""".strip()
+    )
+
+
+def test_multiple_targets():
+    class Machine(RuleBasedStateMachine):
+        a = Bundle("a")
+        b = Bundle("b")
+
+        @initialize(targets=(a, b))
+        def initialize(self):
+            return multiple("ret1", "ret2", "ret3")
+
+        @rule(
+            a1=consumes(a),
+            a2=consumes(a),
+            a3=consumes(a),
+            b1=consumes(b),
+            b2=consumes(b),
+            b3=consumes(b),
+        )
+        def fail_fast(self, a1, a2, a3, b1, b2, b3):
+            raise AssertionError
+
+    Machine.TestCase.settings = NO_BLOB_SETTINGS
+    with pytest.raises(AssertionError) as err:
+        run_state_machine_as_test(Machine)
+
+    result = "\n".join(err.value.__notes__)
+    assert (
+        result
+        == """
+Falsifying example:
+state = Machine()
+a_0, b_0, a_1, b_1, a_2, b_2 = state.initialize()
+state.fail_fast(a1=a_2, a2=a_1, a3=a_0, b1=b_2, b2=b_1, b3=b_0)
+state.teardown()
+""".strip()
+    )
+
+
+def test_multiple_common_targets():
+    class Machine(RuleBasedStateMachine):
+        a = Bundle("a")
+        b = Bundle("b")
+
+        @initialize(targets=(a, b, a))
+        def initialize(self):
+            return multiple("ret1", "ret2", "ret3")
+
+        @rule(
+            a1=consumes(a),
+            a2=consumes(a),
+            a3=consumes(a),
+            a4=consumes(a),
+            a5=consumes(a),
+            a6=consumes(a),
+            b1=consumes(b),
+            b2=consumes(b),
+            b3=consumes(b),
+        )
+        def fail_fast(self, a1, a2, a3, a4, a5, a6, b1, b2, b3):
+            raise AssertionError
+
+    Machine.TestCase.settings = NO_BLOB_SETTINGS
+    with pytest.raises(AssertionError) as err:
+        run_state_machine_as_test(Machine)
+
+    result = "\n".join(err.value.__notes__)
+    assert (
+        result
+        == """
+Falsifying example:
+state = Machine()
+a_0, b_0, a_1, a_2, b_1, a_3, a_4, b_2, a_5 = state.initialize()
+state.fail_fast(a1=a_5, a2=a_4, a3=a_3, a4=a_2, a5=a_1, a6=a_0, b1=b_2, b2=b_1, b3=b_0)
+state.teardown()
+""".strip()
+    )