Fixes #4040, #5378 - signal has no connect member

.gitignore

@@ -15,3 +15,4 @@ astroid.egg-info/
 .pytest_cache/
 .mypy_cache/
 venv
+doc/_build/

ChangeLog

@@ -6,6 +6,10 @@ What's New in astroid 2.12.0?
 =============================
 Release date: TBA
 
+* Fix signal has no ``connect`` member for PySide2 5.15.2+ and PySide6
+
+  Closes #4040, #5378
+
 * ``astroid`` now requires Python 3.7.2 to run.
 
 * Avoid setting a Call as a base for classes created using ``six.with_metaclass()``.

astroid/brain/brain_qt.py

@@ -11,10 +11,16 @@
 
 
 def _looks_like_signal(node, signal_name="pyqtSignal"):
-    if "__class__" in node.instance_attrs:
+    """Detect a Signal node."""
+    klasses = node.instance_attrs.get("__class__", [])
+    # On PySide2 or PySide6 (since  Qt 5.15.2) the Signal class changed locations
+    if node.qname().partition(".")[0] in {"PySide2", "PySide6"}:
+        return any(
+            cls.qname() == "Signal" for cls in klasses
+        )
+    if klasses:
         try:
-            cls = node.instance_attrs["__class__"][0]
-            return cls.name == signal_name
+            return klasses[0].name == signal_name
         except AttributeError:
             # return False if the cls does not have a name attribute
             pass

requirements_test_brain.txt

@@ -3,7 +3,10 @@ types-attrs
 nose
 numpy>=1.17.0; python_version<"3.11"
 python-dateutil
+PyQt5>=5.15.2
+PySide2>=5.15.2; python_version<"3.11"
 PyQt6
+PySide6; python_version<"3.11"
 types-python-dateutil
 six
 types-six

script/.contributors_aliases.json

@@ -169,5 +169,9 @@
   "[email protected]": {
     "mails": ["[email protected]", "[email protected]"],
     "name": "Ville Skyttä"
+  },
+  "[email protected]": {
+    "mails": ["[email protected]"],
+    "name": "Adam Hendry"
   }
 }

tests/unittest_brain_qt.py

@@ -11,12 +11,20 @@
 from astroid.manager import AstroidManager
 from astroid.nodes import FunctionDef
 
+HAS_PYQT5 = find_spec("PyQt5")
+HAS_PYSIDE2 = find_spec("PySide2")
 HAS_PYQT6 = find_spec("PyQt6")
+HAS_PYSIDE6 = find_spec("PySide6")
 
 
-@pytest.mark.skipif(HAS_PYQT6 is None, reason="This test requires the PyQt6 library.")
+@pytest.mark.skipif(
+    HAS_PYSIDE6 is None,
+    reason="These tests require the PyQt6 library.",
+)
 class TestBrainQt:
-    AstroidManager.brain["extension_package_whitelist"] = {"PyQt6"}
+    AstroidManager.brain["extension_package_whitelist"] = {
+        "PyQt6",
+    }
 
     @staticmethod
     def test_value_of_lambda_instance_attrs_is_list():
@@ -70,3 +78,72 @@ def test_slot_disconnect_no_args() -> None:
             pytest.skip("PyQt6 C bindings may not be installed?")
         assert isinstance(attribute_node, FunctionDef)
         assert attribute_node.args.defaults
+
+
+@pytest.mark.skipif(
+    any(
+        (
+            HAS_PYQT5 is None,
+            HAS_PYSIDE2 is None,
+            HAS_PYQT6 is None,
+            HAS_PYSIDE6 is None,
+        ),
+    ),
+    reason="These tests require the PyQt5, PySide2, PyQt6, and PySide6 libraries.",
+)
+class TestBrainQt_ConnectSignalMember:
+    AstroidManager.brain["extension_package_whitelist"] = {
+        "PyQt5",
+        "PySide2",
+        "PyQt6",
+        "PySide6",
+    }
+
+    @staticmethod
+    @pytest.mark.parametrize("qt_binding", ["PyQt5", "PySide2", "PyQt6", "PySide6"])
+    def test_connect_signal_detected(
+        qt_binding: str,
+    ) -> None:
+        """Test signals have .connect() signal.
+
+        This is a regression test for:
+            - https://github.com/PyCQA/pylint/issues/4040
+            - https://github.com/PyCQA/pylint/issues/5378
+
+        See PR: https://github.com/PyCQA/astroid/pull/1654
+
+        Args:
+            qt_binding(str): Python Qt binding (one of PyQt5, PySide2, PyQt6, or PySide6)
+        """
+        if qt_binding == "PyQt5":
+            src = """
+            from PyQt5 import QtWidgets
+            app = QtWidgets.QApplication([])
+            app.focusChanged  #@
+            """
+        elif qt_binding == "PySide2":
+            src = """
+            from PySide2 import QtWidgets
+            app = QtWidgets.QApplication([])
+            app.focusChanged  #@
+            """
+        elif qt_binding == "PyQt6":
+            src = """
+            from PyQt6 import QtWidgets
+            app = QtWidgets.QApplication([])
+            app.focusChanged  #@
+            """
+        elif qt_binding == "PySide6":
+            src = """
+            from PySide6 import QtWidgets
+            app = QtWidgets.QApplication([])
+            app.focusChanged  #@
+            """
+        else:
+            pytest.skip(f"{qt_binding} is not a Python Qt library.")
+
+        node = extract_node(src)
+        attribute_node = node.inferred()[0]
+        if attribute_node is Uninferable:
+            pytest.skip(f"{qt_binding} C bindings may not be installed?")
+        assert isinstance(attribute_node.instance_attrs["connect"][0], FunctionDef)