Import existing LinTunes project

Snapshot of the existing codebase before working through the TASKS.md
backlog. Real library data (data/) and the iTunes import fixture
(itunes-test-library/) are gitignored.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

tests/test_round3.py

@@ -0,0 +1,105 @@
+import hashlib
+import json
+
+import pytest
+
+from lintunes.lastfm import sign, LastFm
+from lintunes.player import make_shuffle_order
+from lintunes.preferences import Preferences
+
+
+class TestLastFmSignature:
+    def test_signature_matches_hand_computed(self):
+        params = {
+            "method": "auth.getMobileSession",
+            "api_key": "KEY",
+            "username": "trav",
+            "password": "hunter2",
+            "format": "json",       # must be excluded from the signature
+        }
+        expected = hashlib.md5(
+            ("api_keyKEY"
+             "methodauth.getMobileSession"
+             "passwordhunter2"
+             "usernametrav"
+             "SECRET").encode()).hexdigest()
+        assert sign(params, "SECRET") == expected
+
+    def test_format_and_callback_excluded(self):
+        base = {"method": "x", "api_key": "k"}
+        with_extras = dict(base, format="json", callback="cb")
+        assert sign(base, "s") == sign(with_extras, "s")
+
+
+class TestScrobbleQueue:
+    def test_queue_round_trip(self, qapp, tmp_path):
+        prefs = Preferences(tmp_path)
+        lastfm = LastFm(prefs, tmp_path)
+        entry = {"artist": "A", "track": "T", "album": "L",
+                 "timestamp": 123, "duration": 180}
+        lastfm._enqueue(entry)
+        assert lastfm._load_queue() == [entry]
+        lastfm._save_queue([])
+        assert lastfm._load_queue() == []
+        assert not (tmp_path / "scrobble_queue.json").exists()
+
+    def test_queue_capped(self, qapp, tmp_path):
+        prefs = Preferences(tmp_path)
+        lastfm = LastFm(prefs, tmp_path)
+        for i in range(600):
+            lastfm._enqueue({"artist": "A", "track": str(i), "timestamp": i})
+        queue = lastfm._load_queue()
+        assert len(queue) == 500
+        assert queue[-1]["track"] == "599"
+
+
+class TestShuffleOrder:
+    def test_permutation_starts_at_current(self):
+        order = make_shuffle_order(10, 4)
+        assert order[0] == 4
+        assert sorted(order) == list(range(10))
+
+    def test_single_track(self):
+        assert make_shuffle_order(1, 0) == [0]
+
+    def test_empty(self):
+        assert make_shuffle_order(0, 0) == []
+
+    def test_is_randomized(self):
+        # With 20 tracks, two consecutive shuffles colliding entirely is
+        # vanishingly unlikely (1/19!)
+        orders = {tuple(make_shuffle_order(20, 0)) for _ in range(5)}
+        assert len(orders) > 1
+
+
+class TestPreferences:
+    def test_defaults(self, qapp, tmp_path):
+        prefs = Preferences(tmp_path)
+        assert prefs.get("ui_scale") == "medium"
+        assert prefs.get("highlight") == "blue"
+        assert prefs.lastfm["scrobble_enabled"] is False
+
+    def test_round_trip(self, qapp, tmp_path):
+        prefs = Preferences(tmp_path)
+        prefs.set("ui_scale", "large")
+        prefs.update_lastfm(username="trav", session_key="abc")
+
+        reloaded = Preferences(tmp_path)
+        assert reloaded.get("ui_scale") == "large"
+        assert reloaded.lastfm["username"] == "trav"
+        assert reloaded.lastfm["session_key"] == "abc"
+        # Unknown/missing keys fall back to defaults
+        assert reloaded.get("highlight") == "blue"
+
+    def test_changed_signal(self, qapp, tmp_path):
+        prefs = Preferences(tmp_path)
+        fired = []
+        prefs.changed.connect(lambda: fired.append(1))
+        prefs.set("highlight", "seafoam")
+        prefs.set("highlight", "seafoam")  # no-op, shouldn't fire again
+        assert len(fired) == 1
+
+    def test_corrupt_file_falls_back(self, qapp, tmp_path):
+        (tmp_path / "preferences.json").write_text("{not json")
+        prefs = Preferences(tmp_path)
+        assert prefs.get("ui_scale") == "medium"