Support for key aliases, key handling tests

tests/test_message_pump.py

@@ -0,0 +1,64 @@
+import pytest
+
+from textual.errors import DuplicateKeyHandlers
+from textual.events import Key
+from textual.widget import Widget
+
+
+class ValidWidget(Widget):
+    called_by = None
+
+    def key_x(self):
+        self.called_by = self.key_x
+
+    def key_ctrl_i(self):
+        self.called_by = self.key_ctrl_i
+
+
+async def test_dispatch_key_valid_key():
+    widget = ValidWidget()
+    result = await widget.dispatch_key(Key(widget, key="x", char="x"))
+    assert result is True
+    assert widget.called_by == widget.key_x
+
+
+async def test_dispatch_key_valid_key_alias():
+    """When you press tab or ctrl+i, it comes through as a tab key event, but handlers for
+    tab and ctrl+i are both considered valid."""
+    widget = ValidWidget()
+    result = await widget.dispatch_key(Key(widget, key="tab", char="\t"))
+    assert result is True
+    assert widget.called_by == widget.key_ctrl_i
+
+
+class DuplicateHandlersWidget(Widget):
+    called_by = None
+
+    def key_x(self):
+        self.called_by = self.key_x
+
+    def _key_x(self):
+        self.called_by = self._key_x
+
+    def key_tab(self):
+        self.called_by = self.key_tab
+
+    def key_ctrl_i(self):
+        self.called_by = self.key_ctrl_i
+
+
+async def test_dispatch_key_raises_when_public_and_private_handlers():
+    """When both a public and private handler exists for one key, we fail fast via exception."""
+    widget = DuplicateHandlersWidget()
+    with pytest.raises(DuplicateKeyHandlers):
+        await widget.dispatch_key(Key(widget, key="x", char="x"))
+    assert widget.called_by is None
+
+
+async def test_dispatch_key_raises_when_conflicting_handler_aliases():
+    """If you've got a handler for e.g. ctrl+i and a handler for tab, that's probably a mistake.
+    In the terminal, they're the same thing, so we fail fast via exception here."""
+    widget = DuplicateHandlersWidget()
+    with pytest.raises(DuplicateKeyHandlers):
+        await widget.dispatch_key(Key(widget, key="tab", char="\t"))
+    assert widget.called_by == widget.key_tab