test: add test suite for player, api and widgets

tests/test_timezone.py

@@ -0,0 +1,48 @@
+from __future__ import annotations
+
+from datetime import datetime, timedelta, timezone
+from pathlib import Path
+
+import pytest
+
+from somafm_tui.widgets import common
+
+BERLIN = Path("/usr/share/zoneinfo/Europe/Berlin")
+UTC_FILE = Path("/usr/share/zoneinfo/UTC")
+
+
+@pytest.fixture(autouse=True)
+def clear_zone_cache():
+    common.local_zone.cache_clear()
+    yield
+    common.local_zone.cache_clear()
+
+
+def _copy_zone(tmp_path: Path, source: Path) -> Path:
+    target = tmp_path / "localtime"
+    target.write_bytes(source.read_bytes())
+    return target
+
+
+def test_build_time_tz_utc_does_not_hide_the_system_zone(tmp_path, monkeypatch) -> None:
+    if not BERLIN.exists():
+        pytest.skip("system tzdata is not installed")
+    monkeypatch.setattr(common, "LOCALTIME_PATH", str(_copy_zone(tmp_path, BERLIN)))
+    monkeypatch.setenv("TZ", "UTC")
+
+    zone = common.local_zone()
+    assert zone.utcoffset(datetime(2026, 1, 1)) == timedelta(hours=1)
+
+    aware = datetime(2026, 1, 1, 12, 0, tzinfo=timezone.utc)
+    assert common.local_time(aware) == "13:00"
+
+
+def test_explicit_non_utc_tz_is_respected(tmp_path, monkeypatch) -> None:
+    if not BERLIN.exists() or not UTC_FILE.exists():
+        pytest.skip("system tzdata is not installed")
+    monkeypatch.setattr(common, "LOCALTIME_PATH", str(_copy_zone(tmp_path, UTC_FILE)))
+    monkeypatch.setenv("TZ", "Europe/Berlin")
+
+    zone = common.local_zone()
+    assert zone.utcoffset(datetime(2026, 1, 1)) == timedelta(hours=1)
+    assert common.local_time(datetime(2026, 1, 1, 12, 0, tzinfo=timezone.utc)) == "13:00"