feat(catalogue): tune a single-station catalogue on switch

tests/test_providers.py

@@ -257,3 +257,72 @@ async def test_every_catalogue_header_is_the_same_height() -> None:
             assert header.styles.height.value == 4, slug
             lines = [line.plain for line in header.render().renderables]
             assert any("STOPPED" in line or "PLAYING" in line for line in lines), slug
+
+
+class _StubPlayer:
+    """Just enough Player for a tune: records what mpv would have played."""
+
+    def __init__(self) -> None:
+        import queue
+
+        self.events: queue.Queue = queue.Queue()
+        self.played: list[list[str]] = []
+        self.volume: int | None = None
+        self.backend: str | None = None
+
+    def play(self, urls) -> None:
+        self.played.append(list(urls))
+
+    def set_volume(self, value: int) -> None:
+        self.volume = value
+
+    def stop(self) -> None:
+        pass
+
+    def toggle_pause(self) -> None:
+        pass
+
+
+async def _switch_to(app, pilot, slug: str) -> None:
+    slugs = available_providers()
+    steps = (slugs.index(slug) - slugs.index(app.provider.id)) % len(slugs)
+    await pilot.press("p")
+    await pilot.pause()
+    for _ in range(steps):
+        await pilot.press("down")
+    await pilot.press("enter")
+    await pilot.pause()
+    await pilot.pause()
+
+
+@pytest.mark.asyncio
+async def test_switching_to_a_single_station_catalogue_tunes_it() -> None:
+    app = _CatalogueApp("somafm").app
+    async with app.run_test(size=(110, 40)) as pilot:
+        await pilot.pause()
+        stub = _StubPlayer()
+        app.player = stub
+        app.audio_enabled = True
+
+        await _switch_to(app, pilot, "tilderadio")
+
+        assert app.provider.id == "tilderadio"
+        assert app.current is not None and app.current.id == "tilderadio"
+        assert stub.played, "a one-station catalogue should start playing"
+        assert app.playing_state != "stopped"
+
+
+@pytest.mark.asyncio
+async def test_switching_to_a_multi_station_catalogue_waits_for_enter() -> None:
+    app = _CatalogueApp("tilderadio").app
+    async with app.run_test(size=(110, 40)) as pilot:
+        await pilot.pause()
+        stub = _StubPlayer()
+        app.player = stub
+        app.audio_enabled = True
+
+        await _switch_to(app, pilot, "somafm")
+
+        assert app.provider.id == "somafm"
+        assert len(app.stations) > 1
+        assert stub.played == [], "multi-station catalogues wait for enter"