feat(ui): draw pane frames, page keys and a scroll thumb

tests/test_station_list.py

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+"""The station pane: paging, the position readout and the scrollbar."""
+
+from __future__ import annotations
+
+import re
+
+import pytest
+
+from beefy_player.app import BeefyPlayerApp
+from beefy_player.widgets.station_list import StationList
+
+
+def app_for(provider: str, *, offline: bool = True) -> BeefyPlayerApp:
+    return BeefyPlayerApp(provider=provider, autoplay=False, offline=offline, audio=False)
+
+
+def test_thumb_geometry() -> None:
+    # nothing to scroll: the whole track is the thumb
+    assert StationList.thumb(10, 10, 0) == set(range(10))
+    # top of a long list
+    top = StationList.thumb(10, 100, 0)
+    assert 0 in top and len(top) >= 1
+    # bottom of the same list ends at the last row
+    bottom = StationList.thumb(10, 100, 90)
+    assert 9 in bottom
+    # mid-list sits between the two
+    middle = StationList.thumb(10, 100, 45)
+    assert min(middle) > min(top) and max(middle) < max(bottom)
+
+
+@pytest.mark.asyncio
+async def test_paging_moves_a_screen_and_back() -> None:
+    app = app_for("somafm")
+    async with app.run_test(size=(100, 26)) as pilot:
+        await pilot.pause()
+        pane = app.query_one(StationList)
+        page = pane.size.height - 1
+        start = app.index
+
+        await pilot.press("pagedown")
+        await pilot.pause()
+        assert app.index == min(start + page, len(app.view) - 1)
+
+        await pilot.press("pageup")
+        await pilot.pause()
+        assert app.index == start
+
+        # the bottom of the list clamps instead of wrapping
+        await pilot.press("shift+g", "pagedown")
+        await pilot.pause()
+        assert app.index == len(app.view) - 1
+
+
+@pytest.mark.asyncio
+async def test_the_title_reads_out_the_position() -> None:
+    app = app_for("somafm")
+    async with app.run_test(size=(100, 26)) as pilot:
+        await pilot.pause()
+        pane = app.query_one(StationList)
+        assert re.fullmatch(r"STATIONS · \d+/\d+", pane.border_title)
+        await pilot.press("down")
+        await pilot.pause()
+        first, total = pane.border_title.split(" · ")[1].split("/")
+        assert int(total) == len(app.view)
+        assert int(first) == app.index + 1
+
+
+@pytest.mark.asyncio
+async def test_the_scrollbar_appears_only_when_the_list_overflows() -> None:
+    app = app_for("somafm")
+    async with app.run_test(size=(100, 26)) as pilot:
+        await pilot.pause()
+        pane = app.query_one(StationList)
+        rows = [line.plain for line in pane.render().renderables]
+        assert rows[0].startswith("╭") and rows[-1].startswith("╰")
+        content = rows[1:-1]
+        # thumb only, in the frame grey: blank cells elsewhere, no rail
+        assert all(row[-2] in "▐ " for row in content)
+        assert any(row[-2] == "▐" for row in content)
+
+    app = app_for("rinse")  # three stations, no scrolling
+    async with app.run_test(size=(100, 26)) as pilot:
+        await pilot.pause()
+        pane = app.query_one(StationList)
+        rows = [line.plain for line in pane.render().renderables]
+        assert rows[0].startswith("╭") and rows[-1].startswith("╰")
+        assert sum("Rinse" in row or "Kool" in row or "SWU" in row for row in rows) == 3
+        # three stations fit: no thumb in the content rows
+        assert not any(row[-2] == "▐" for row in rows[1:-1])
+
+
+@pytest.mark.asyncio
+async def test_the_filter_keeps_the_readout_in_step() -> None:
+    app = app_for("somafm")
+    async with app.run_test(size=(100, 26)) as pilot:
+        await pilot.pause()
+        await pilot.press("slash")
+        await pilot.pause()
+        app.query_one("SearchInput").value = "drone"
+        await pilot.pause()
+        pane = app.query_one(StationList)
+        assert pane.border_title.startswith("STATIONS · /drone · ")
+        filtered = len(app.view)
+        assert pane.border_title.endswith(f"/{filtered}")