Move abstract methods to AbstractConnectionPool (#6340)

Author: ewjoachim

stubs/psycopg2/@tests/stubtest_allowlist.txt

@@ -1,2 +1,5 @@
 psycopg2.connection
 psycopg2.cursor
+psycopg2.pool.AbstractConnectionPool.closeall
+psycopg2.pool.AbstractConnectionPool.getconn
+psycopg2.pool.AbstractConnectionPool.putconn

stubs/psycopg2/psycopg2/pool.pyi

@@ -9,14 +9,15 @@ class AbstractConnectionPool:
     maxconn: Any
     closed: bool
     def __init__(self, minconn, maxconn, *args, **kwargs) -> None: ...
+    # getconn, putconn and closeall are officially documented as methods of the
+    # abstract base class, but in reality, they only exist on the children classes
+    def getconn(self, key: Any | None = ...): ...
+    def putconn(self, conn: Any, key: Any | None = ..., close: bool = ...) -> None: ...
+    def closeall(self) -> None: ...
 
-class SimpleConnectionPool(AbstractConnectionPool):
-    getconn: Any
-    putconn: Any
-    closeall: Any
+class SimpleConnectionPool(AbstractConnectionPool): ...
 
 class ThreadedConnectionPool(AbstractConnectionPool):
-    def __init__(self, minconn, maxconn, *args, **kwargs) -> None: ...
-    def getconn(self, key: Any | None = ...): ...
+    # This subclass has a default value for conn which doesn't exist
+    # in the SimpleConnectionPool class, nor in the documentation
     def putconn(self, conn: Any | None = ..., key: Any | None = ..., close: bool = ...) -> None: ...
-    def closeall(self) -> None: ...