Merge pull request #23 from syastrov/better-types-for-transaction-atomic

Add better typings plus test for transaction.atomic.

test-data/typecheck/transaction.test

@@ -0,0 +1,50 @@
+[CASE test_transaction_atomic]
+
+from django.db import transaction
+
+with transaction.atomic():
+    pass
+
+with transaction.atomic(using="mydb"):
+    pass
+
+with transaction.atomic(using="mydb", savepoint=False):
+    pass
+
+@transaction.atomic()
+def decorated_func(param1: str, param2: int) -> bool:
+    pass
+
+# Ensure that the function's type is preserved
+reveal_type(decorated_func)  # E: Revealed type is 'def (param1: builtins.str, param2: builtins.int) -> builtins.bool'
+
+@transaction.atomic(using="mydb")
+def decorated_func_using(param1: str, param2: int) -> bool:
+    pass
+
+# Ensure that the function's type is preserved
+reveal_type(decorated_func_using)  # E: Revealed type is 'def (param1: builtins.str, param2: builtins.int) -> builtins.bool'
+
+class ClassWithAtomicMethod:
+    # Bare decorator
+    @transaction.atomic
+    def atomic_method1(self, abc: int) -> str:
+        pass
+
+    @transaction.atomic(savepoint=True)
+    def atomic_method2(self):
+        pass
+
+    @transaction.atomic(using="db", savepoint=True)
+    def atomic_method3(self, myparam: str) -> int:
+        pass
+
+ClassWithAtomicMethod().atomic_method1("abc") # E: Argument 1 to "atomic_method1" of "ClassWithAtomicMethod" has incompatible type "str"; expected "int"
+
+# Ensure that the method's type is preserved
+reveal_type(ClassWithAtomicMethod().atomic_method1) # E: Revealed type is 'def (abc: builtins.int) -> builtins.str'
+
+# Ensure that the method's type is preserved
+reveal_type(ClassWithAtomicMethod().atomic_method3) # E: Revealed type is 'def (myparam: builtins.str) -> builtins.int'
+
+[out]