Fix inspect.signature introspection for attrgetter/itemgetter/methodcaller (#7111)

* Fix attrgetter signature introspection in operator

* Fix itemgetter signature introspection in operator

* Fix methodcaller signature introspection in operator

Lib/test/test_operator.py

@@ -668,18 +668,6 @@ class PyOperatorTestCase(OperatorTestCase, unittest.TestCase):
 class COperatorTestCase(OperatorTestCase, unittest.TestCase):
     module = c_operator
 
-    @unittest.expectedFailure  # TODO: RUSTPYTHON
-    def test_attrgetter_signature(self):
-        return super().test_attrgetter_signature()
-
-    @unittest.expectedFailure  # TODO: RUSTPYTHON
-    def test_itemgetter_signature(self):
-        return super().test_itemgetter_signature()
-
-    @unittest.expectedFailure  # TODO: RUSTPYTHON
-    def test_methodcaller_signature(self):
-        return super().test_methodcaller_signature()
-
 
 @support.thread_unsafe("swaps global operator module")
 class OperatorPickleTestCase:

crates/vm/src/stdlib/operator.rs

@@ -340,7 +340,8 @@ mod _operator {
         Ok(res)
     }
 
-    /// attrgetter(attr, ...) --> attrgetter object
+    /// attrgetter(attr, /, *attrs)
+    /// --
     ///
     /// Return a callable object that fetches the given attribute(s) from its operand.
     /// After f = attrgetter('name'), the call f(r) returns r.name.
@@ -356,6 +357,11 @@ mod _operator {
 
     #[pyclass(with(Callable, Constructor, Representable))]
     impl PyAttrGetter {
+        #[pygetset]
+        fn __text_signature__(&self) -> &'static str {
+            "(obj, /)"
+        }
+
         #[pymethod]
         fn __reduce__(zelf: PyRef<Self>, vm: &VirtualMachine) -> PyResult<(PyTypeRef, PyTupleRef)> {
             let attrs = vm
@@ -440,7 +446,8 @@ mod _operator {
         }
     }
 
-    /// itemgetter(item, ...) --> itemgetter object
+    /// itemgetter(item, /, *items)
+    /// --
     ///
     /// Return a callable object that fetches the given item(s) from its operand.
     /// After f = itemgetter(2), the call f(r) returns r[2].
@@ -454,6 +461,11 @@ mod _operator {
 
     #[pyclass(with(Callable, Constructor, Representable))]
     impl PyItemGetter {
+        #[pygetset]
+        fn __text_signature__(&self) -> &'static str {
+            "(obj, /)"
+        }
+
         #[pymethod]
         fn __reduce__(zelf: PyRef<Self>, vm: &VirtualMachine) -> PyObjectRef {
             let items = vm.ctx.new_tuple(zelf.items.to_vec());
@@ -507,7 +519,8 @@ mod _operator {
         }
     }
 
-    /// methodcaller(name, ...) --> methodcaller object
+    /// methodcaller(name, /, *args, **kwargs)
+    /// --
     ///
     /// Return a callable object that calls the given method on its operand.
     /// After f = methodcaller('name'), the call f(r) returns r.name().
@@ -523,6 +536,11 @@ mod _operator {
 
     #[pyclass(with(Callable, Constructor, Representable))]
     impl PyMethodCaller {
+        #[pygetset]
+        fn __text_signature__(&self) -> &'static str {
+            "(obj, /)"
+        }
+
         #[pymethod]
         fn __reduce__(zelf: PyRef<Self>, vm: &VirtualMachine) -> PyResult<PyTupleRef> {
             // With no kwargs, return (type(obj), (name, *args)) tuple.