Add initial radio button tests

tests/toggles/test_radiobutton.py

@@ -0,0 +1,47 @@
+from __future__ import annotations
+
+from textual.app import App, ComposeResult
+from textual.widgets import RadioButton
+
+
+class RadioButtonApp(App[None]):
+    def __init__(self):
+        super().__init__()
+        self.events_received = []
+
+    def compose(self) -> ComposeResult:
+        yield RadioButton("Test", id="rb1")
+        yield RadioButton(id="rb2")
+        yield RadioButton(value=True, id="rb3")
+
+    def on_radio_button_changed(self, event: RadioButton.Changed) -> None:
+        self.events_received.append((event.input.id, event.input.value))
+
+
+async def test_radio_button_initial_state() -> None:
+    """The initial states of the radio buttons should be as we specified."""
+    async with RadioButtonApp().run_test() as pilot:
+        assert [button.value for button in pilot.app.query(RadioButton)] == [
+            False,
+            False,
+            True,
+        ]
+        assert pilot.app.events_received == []
+
+
+async def test_radio_button_toggle() -> None:
+    """The initial states of the radio buttons should be as we specified."""
+    async with RadioButtonApp().run_test() as pilot:
+        for box in pilot.app.query(RadioButton):
+            box.toggle()
+        assert [button.value for button in pilot.app.query(RadioButton)] == [
+            True,
+            True,
+            False,
+        ]
+        await pilot.pause()
+        assert pilot.app.events_received == [
+            ("rb1", True),
+            ("rb2", True),
+            ("rb3", False),
+        ]