Improve ENABLE_CONTRACT_CHECKING handling in contract-checking custom…

… setattr (#932)

CHANGELOG.md

@@ -30,6 +30,8 @@ and adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
   outer function, efficiency of code was improved, and the attribute value is now restored to the original value if the
   `_check_invariants` call raises an error.
 - Added new function `validate_invariants` which takes in an object and checks that the representation invariants of the object are satisfied.
+- The check for `ENABLE_CONTRACT_CHECKING` is now moved to the top of the body of the `new_setattr` function.
+- Added the file `conftest.py` to store `pytest` fixtures.
 
 ### Bug Fixes
 

python_ta/contracts/__init__.py

@@ -147,6 +147,9 @@ def new_setattr(self: klass, name: str, value: Any) -> None:
 
         Check representation invariants for this class when not within an instance method of the class.
         """
+        if not ENABLE_CONTRACT_CHECKING:
+            super(klass, self).__setattr__(name, value)
+            return
         if name in cls_annotations:
             try:
                 _debug(f"Checking type of attribute {attr} for {klass.__qualname__} instance")
@@ -165,7 +168,7 @@ def new_setattr(self: klass, name: str, value: Any) -> None:
         frame_locals = inspect.currentframe().f_back.f_locals
         if self is not frame_locals.get("self"):
             # Only validating if the attribute is not being set in a instance/class method
-            if klass_mod is not None and ENABLE_CONTRACT_CHECKING:
+            if klass_mod is not None:
                 try:
                     _check_invariants(self, klass, klass_mod.__dict__)
                 except PyTAContractError as e:

tests/conftest.py

@@ -0,0 +1,11 @@
+import pytest
+
+import python_ta.contracts
+
+
+@pytest.fixture()
+def disable_contract_checking():
+    """Fixture for setting python_ta.contracts.ENABLE_CONTRACT_CHECKING = False."""
+    python_ta.contracts.ENABLE_CONTRACT_CHECKING = False
+    yield
+    python_ta.contracts.ENABLE_CONTRACT_CHECKING = True

tests/test_class_contracts.py

@@ -240,15 +240,13 @@ def test_pizza_invalid() -> None:
     )
 
 
-def test_pizza_invalid_disable_contract_checking() -> None:
+def test_pizza_invalid_disable_contract_checking(disable_contract_checking) -> None:
     """
     Test the Pizza representation invariant on an invalid instance but with ENABLE_CONTRACT_CHECKING = False so
     no error is raised.
     """
-    python_ta.contracts.ENABLE_CONTRACT_CHECKING = False
     pizza = Pizza(radius=10, ingredients=[])
     assert pizza.radius == 10 and pizza.ingredients == []
-    python_ta.contracts.ENABLE_CONTRACT_CHECKING = True  # Reset default value to True
 
 
 def test_set_wrapper_valid() -> None:

tests/test_contracts.py

@@ -123,17 +123,15 @@ def nullary() -> bool:
         nullary()
 
 
-def test_nullary_int_bool_disable_contract_checking() -> None:
+def test_nullary_int_bool_disable_contract_checking(disable_contract_checking) -> None:
     """Calling a nullary function with incorrect return type and with ENABLE_CONTRACT_CHECKING disabled so no error
     is raised."""
 
     @check_contracts
     def nullary() -> int:
         return True
 
-    python_ta.contracts.ENABLE_CONTRACT_CHECKING = False
     nullary()
-    python_ta.contracts.ENABLE_CONTRACT_CHECKING = True  # Reset default value to True
 
 
 def test_nullary_no_return_type() -> None:
@@ -233,14 +231,12 @@ def parameter_bool(result: bool) -> None:
         parameter_bool(1)
 
 
-def test_parameter_int_bool_disable_contract_checking() -> None:
+def test_parameter_int_bool_disable_contract_checking(disable_contract_checking) -> None:
     @check_contracts
     def parameter_int(num: int) -> None:
         return None
 
-    python_ta.contracts.ENABLE_CONTRACT_CHECKING = False
     parameter_int(True)
-    python_ta.contracts.ENABLE_CONTRACT_CHECKING = True  # Reset default value to True
 
 
 @check_contracts
@@ -274,12 +270,10 @@ def test_my_sum_one_pre_violation() -> None:
     assert "len(numbers) > 2" in msg
 
 
-def test_my_sum_one_disable_contract_checking() -> None:
+def test_my_sum_one_disable_contract_checking(disable_contract_checking) -> None:
     """Calling _my_sum_one_precondition with a value that violates the precondition but with ENABLE_CONTRACT_CHECKING
     = False so no error is raised"""
-    python_ta.contracts.ENABLE_CONTRACT_CHECKING = False
     _my_sum_one_precondition([1])
-    python_ta.contracts.ENABLE_CONTRACT_CHECKING = True  # Reset default value to True
 
 
 # Checking to see if functions we defined are in-scope for preconditions
@@ -449,13 +443,11 @@ def test_get_double_invalid() -> None:
     assert "$return_value == num * 2" in msg
 
 
-def test_get_double_disabled_contract_checking() -> None:
+def test_get_double_disabled_contract_checking(disable_contract_checking) -> None:
     """Test that calling the invalid implementation of _get_double does NOT raise an AssertionError when
     ENABLE_CONTRACT_CHECKING is False.
     """
-    python_ta.contracts.ENABLE_CONTRACT_CHECKING = False
     assert _get_double_invalid(5) == 11
-    python_ta.contracts.ENABLE_CONTRACT_CHECKING = True  # Reset default value to True
 
 
 # Test that postcondition checks involving function parameters pass and fail as expected
@@ -686,16 +678,6 @@ def test_check_all_contracts_module_names_argument() -> None:
         run()
 
 
-@pytest.fixture()
-def disable_contract_checking():
-    """Fixture for setting python_ta.contracts.ENABLE_CONTRACT_CHECKING = False."""
-    import python_ta.contracts
-
-    python_ta.contracts.ENABLE_CONTRACT_CHECKING = False
-    yield
-    python_ta.contracts.ENABLE_CONTRACT_CHECKING = True
-
-
 def test_enable_contract_checking_false(disable_contract_checking) -> None:
     """Test that check_contracts does nothing when ENABLE_CONTRACT_CHECKING is False."""
 
@@ -705,3 +687,18 @@ def unary2(arg: int) -> int:
 
     # No error should be raised even though the argument is the wrong type
     assert unary2("wrong type!") == "wrong type!"
+
+
+def test_invalid_attr_type_disable_contract_checking(disable_contract_checking) -> None:
+    """
+    Test that a Person object is created with an attribute value that doesn't match the specified type annotation but
+    with ENABLE_CONTRACT_CHECKING = False so no error is raised.
+    """
+
+    @check_contracts
+    class Person:
+        age: int
+
+    my_person = Person()
+    my_person.age = "John"
+    assert my_person.age == "John"