twisted#12046 Fix handling of function keys in conch.insults.window.W…

…idget object (twisted#12047)

twisted.conch.insults.window.Widget.functionKeyReceived now dispatches functional key events to corresponding `func_KEYNAME` methods, where `KEYNAME` can be `F1`, `F2`, `HOME`, `UP_ARROW` etc. This is a regression introduced with twisted#8214 in Twisted 16.5.0, where events changed from `const` objects to bytestrings in square brackets like `[F1]`.

src/twisted/conch/insults/insults.py

@@ -431,23 +431,7 @@ def log(s):
     "CONTROL",
 )
 
-
-class _const:
-    """
-    @ivar name: A string naming this constant
-    """
-
-    def __init__(self, name: str) -> None:
-        self.name = name
-
-    def __repr__(self) -> str:
-        return "[" + self.name + "]"
-
-    def __bytes__(self) -> bytes:
-        return ("[" + self.name + "]").encode("ascii")
-
-
-FUNCTION_KEYS = [_const(_name).__bytes__() for _name in _KEY_NAMES]
+FUNCTION_KEYS = [f"[{_name}]".encode("ascii") for _name in _KEY_NAMES]
 
 
 @implementer(ITerminalTransport)

src/twisted/conch/insults/window.py

@@ -6,6 +6,8 @@
 @author: Jp Calderone
 """
 
+from __future__ import annotations
+
 import array
 
 from twisted.conch.insults import helper, insults
@@ -47,7 +49,8 @@ class Widget:
     focused = False
     parent = None
     dirty = False
-    width = height = None
+    width: int | None = None
+    height: int | None = None
 
     def repaint(self):
         if not self.dirty:
@@ -109,7 +112,12 @@ def functionKeyReceived(self, keyID, modifier):
         name = keyID
         if not isinstance(keyID, str):
             name = name.decode("utf-8")
-        func = getattr(self, "func_" + name, None)
+
+        # Peel off the square brackets added by the computed definition of
+        # twisted.conch.insults.insults.FUNCTION_KEYS.
+        methodName = "func_" + name[1:-1]
+
+        func = getattr(self, methodName, None)
         if func is not None:
             func(modifier)
 

src/twisted/conch/newsfragments/12046.bugfix

@@ -0,0 +1 @@
+twisted.conch.insults.window.Widget.functionKeyReceived now dispatches functional key events to corresponding `func_KEYNAME` methods, where `KEYNAME` can be `F1`, `F2`, `HOME`, `UP_ARROW` etc. This is a regression introduced with #8214 in Twisted 16.5.0, where events changed from `const` objects to bytestrings in square brackets like `[F1]`.

src/twisted/conch/test/test_window.py

@@ -5,7 +5,14 @@
 
 from typing import Callable
 
-from twisted.conch.insults.window import ScrolledArea, TextOutput, TopWindow
+from twisted.conch.insults.insults import ServerProtocol
+from twisted.conch.insults.window import (
+    ScrolledArea,
+    Selection,
+    TextOutput,
+    TopWindow,
+    Widget,
+)
 from twisted.trial.unittest import TestCase
 
 
@@ -66,3 +73,100 @@ def test_parent(self) -> None:
         scrolled = ScrolledArea(widget)
         self.assertIs(widget.parent, scrolled._viewport)
         self.assertIs(scrolled._viewport.parent, scrolled)
+
+
+class SelectionTests(TestCase):
+    """
+    Change focused entry in L{Selection} using function keys.
+    """
+
+    def setUp(self) -> None:
+        """
+        Create L{ScrolledArea} widget with 10 elements and position selection to 5th element.
+        """
+        seq: list[bytes] = [f"{_num}".encode("ascii") for _num in range(10)]
+        self.widget = Selection(seq, None)
+        self.widget.height = 10
+        self.widget.focusedIndex = 5
+
+    def test_selectionDownArrow(self) -> None:
+        """
+        Send DOWN_ARROW to select element just below the current one.
+        """
+        self.widget.keystrokeReceived(ServerProtocol.DOWN_ARROW, None)  # type: ignore[attr-defined]
+        self.assertIs(self.widget.focusedIndex, 6)
+
+    def test_selectionUpArrow(self) -> None:
+        """
+        Send UP_ARROW to select element just above the current one.
+        """
+        self.widget.keystrokeReceived(ServerProtocol.UP_ARROW, None)  # type: ignore[attr-defined]
+        self.assertIs(self.widget.focusedIndex, 4)
+
+    def test_selectionPGDN(self) -> None:
+        """
+        Send PGDN to select element one page down (here: last element).
+        """
+        self.widget.keystrokeReceived(ServerProtocol.PGDN, None)  # type: ignore[attr-defined]
+        self.assertIs(self.widget.focusedIndex, 9)
+
+    def test_selectionPGUP(self) -> None:
+        """
+        Send PGUP to select element one page up (here: first element).
+        """
+        self.widget.keystrokeReceived(ServerProtocol.PGUP, None)  # type: ignore[attr-defined]
+        self.assertIs(self.widget.focusedIndex, 0)
+
+
+class RecordingWidget(Widget):
+    """
+    A dummy Widget implementation to test handling of function keys by
+    recording keyReceived events.
+    """
+
+    def __init__(self) -> None:
+        Widget.__init__(self)
+        self.triggered: list[str] = []
+
+    def func_F1(self, modifier: str) -> None:
+        self.triggered.append("F1")
+
+    def func_HOME(self, modifier: str) -> None:
+        self.triggered.append("HOME")
+
+    def func_DOWN_ARROW(self, modifier: str) -> None:
+        self.triggered.append("DOWN_ARROW")
+
+    def func_UP_ARROW(self, modifier: str) -> None:
+        self.triggered.append("UP_ARROW")
+
+    def func_PGDN(self, modifier: str) -> None:
+        self.triggered.append("PGDN")
+
+    def func_PGUP(self, modifier: str) -> None:
+        self.triggered.append("PGUP")
+
+
+class WidgetFunctionKeyTests(TestCase):
+    """
+    Call functionKeyReceived with key values from insults.ServerProtocol
+    """
+
+    def test_functionKeyReceivedDispatch(self) -> None:
+        """
+        L{Widget.functionKeyReceived} dispatches its input, a constant on
+        ServerProtocol, to a matched C{func_KEY} method.
+        """
+        widget = RecordingWidget()
+
+        def checkOneKey(key: str) -> None:
+            widget.functionKeyReceived(getattr(ServerProtocol, key), None)
+            self.assertEqual([key], widget.triggered)
+            widget.triggered.clear()
+
+        checkOneKey("F1")
+        checkOneKey("HOME")
+        checkOneKey("DOWN_ARROW")
+        checkOneKey("UP_ARROW")
+        checkOneKey("PGDN")
+        checkOneKey("PGUP")