diff --git a/pyproject.toml b/pyproject.toml
index 69151e7..3f9ca1c 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -2,7 +2,7 @@
 name = "mopidy-smartplaylists"
 description = "Mopidy extension for generating smart playlists based on track properties"
 readme = "README.md"
-requires-python = ">= 3.13"
+requires-python = ">= 3.10"
 license = { text = "Apache-2.0" }
 authors = [{ name = "Chris Powell", email = "chris@code.unbl.ink" }]
 classifiers = [
@@ -14,9 +14,9 @@ classifiers = [
 ]
 dynamic = ["version"]
 dependencies = [
-    "mopidy >= 4.0.0",
-    "pykka >= 4.1",
-    "tornado >= 6.4",
+    "mopidy >= 3.0.0",
+    "pykka >= 2.0.1",
+    "tornado >= 4.4",
 ]
 
 [project.urls]
@@ -54,7 +54,7 @@ show_missing = true
 
 
 [tool.pyright]
-pythonVersion = "3.13"
+pythonVersion = "3.10"
 typeCheckingMode = "standard"
 reportMissingTypeStubs = false
 reportPrivateImportUsage = false
@@ -67,7 +67,7 @@ filterwarnings = [
 
 
 [tool.ruff]
-target-version = "py313"
+target-version = "py310"
 
 [tool.ruff.lint]
 select = ["ALL"]
@@ -105,6 +105,9 @@ ignore = [
 
 [tool.tox]
 env_list = [
+    "3.10",
+    "3.11",
+    "3.12",
     "3.13",
     "3.14",
     "pyright",
diff --git a/src/mopidy_smartplaylists/__init__.py b/src/mopidy_smartplaylists/__init__.py
index c72e826..6224155 100644
--- a/src/mopidy_smartplaylists/__init__.py
+++ b/src/mopidy_smartplaylists/__init__.py
@@ -2,7 +2,6 @@ import pathlib
 from importlib.metadata import version
 
 from mopidy import config, ext
-from mopidy.config import ConfigSchema
 
 __version__ = version("mopidy-smartplaylists")
 
@@ -12,10 +11,10 @@ class Extension(ext.Extension):
     ext_name = "smartplaylists"
     version = __version__
 
-    def get_default_config(self):
+    def get_default_config(self) -> str:
         return config.read(pathlib.Path(__file__).parent / "ext.conf")
 
-    def get_config_schema(self):
+    def get_config_schema(self) -> config.ConfigSchema:
         schema = super().get_config_schema()
         schema["decades"] = config.String(optional=True)
         schema["genres"] = config.String(optional=True)
@@ -24,16 +23,19 @@ class Extension(ext.Extension):
         schema["refresh_interval"] = config.Integer(optional=True, minimum=0)
         return schema
 
-    def validate_environment(self):
+    def validate_environment(self) -> None:
         pass
 
-    def setup(self, registry):
+    def setup(self, registry: ext.Registry) -> None:
         from mopidy_smartplaylists.web import app_factory
 
-        registry.add("http:app", {
-            "name": self.ext_name,
-            "factory": app_factory,
-        })
+        registry.add(
+            "http:app",
+            {
+                "name": self.ext_name,
+                "factory": app_factory,
+            },
+        )
 
         from mopidy_smartplaylists.frontend import SmartPlaylistsFrontend
 
diff --git a/src/mopidy_smartplaylists/compat.py b/src/mopidy_smartplaylists/compat.py
new file mode 100644
index 0000000..8231a2e
--- /dev/null
+++ b/src/mopidy_smartplaylists/compat.py
@@ -0,0 +1,23 @@
+"""
+Compatibility layer for Mopidy 3 vs 4 differences.
+
+Provides import aliases for APIs that differ between Mopidy 3 and 4:
+
+- ``CoreProxy`` / ``Config`` are available in both but under different modules.
+- ``mopidy.types`` (``Uri``, ``SearchField``, ``Query``) only exists in Mopidy 4.
+"""
+
+from __future__ import annotations
+
+from typing import TYPE_CHECKING, Any
+
+if TYPE_CHECKING:
+    from mopidy.config import Config
+    from mopidy.core import CoreProxy
+    from mopidy.types import Query, SearchField, Uri
+else:
+    CoreProxy = Any
+    Config = dict[str, dict[str, Any]]
+    Uri = str
+    SearchField = str
+    Query = dict
diff --git a/src/mopidy_smartplaylists/frontend.py b/src/mopidy_smartplaylists/frontend.py
index bbaf0c7..5da1c31 100644
--- a/src/mopidy_smartplaylists/frontend.py
+++ b/src/mopidy_smartplaylists/frontend.py
@@ -1,11 +1,16 @@
+from __future__ import annotations
+
 import logging
+from typing import TYPE_CHECKING
 
 import pykka
-from mopidy.config import Config
-from mopidy.core import CoreListener, CoreProxy
+from mopidy.core import CoreListener
 
 from mopidy_smartplaylists.generators import refresh_smart_playlists
 
+if TYPE_CHECKING:
+    from mopidy_smartplaylists.compat import Config, CoreProxy
+
 logger = logging.getLogger(__name__)
 
 
diff --git a/src/mopidy_smartplaylists/generators.py b/src/mopidy_smartplaylists/generators.py
index 896b3b2..df5f6be 100644
--- a/src/mopidy_smartplaylists/generators.py
+++ b/src/mopidy_smartplaylists/generators.py
@@ -1,23 +1,32 @@
+from __future__ import annotations
+
 import logging
 import re
+from typing import TYPE_CHECKING, cast
 
-from mopidy.core import CoreProxy
-from mopidy.models import Playlist, Track, TrackField
+from mopidy.models import Playlist, Track
+
+if TYPE_CHECKING:
+    from mopidy_smartplaylists.compat import CoreProxy, Query, SearchField, Uri
 
 logger = logging.getLogger(__name__)
 
 
 def parse_decade(decade_str: str) -> str:
-    decade_str = decade_str.strip()
-    if len(decade_str) == 4:
-        return decade_str[:3] + "*"
-    if decade_str.endswith("s"):
+    decade_str = decade_str.strip().rstrip("s")
+    if len(decade_str) >= 3:
         return decade_str[:3] + "*"
     return decade_str
 
 
+def _search(core: CoreProxy, field: str, value: str) -> list[Track]:
+    query = cast("Query[SearchField]", {field: [value]})
+    result = core.library.search(query).get()
+    return _extract_tracks(result)
+
+
 def build_decade_mix(core: CoreProxy, decade: str) -> list[Track]:
-    query = {TrackField.DATE: [parse_decade(decade)]}
+    query = cast("Query[SearchField]", {"date": [parse_decade(decade)]})
     result = core.library.search(query).get()
     tracks = _extract_tracks(result)
     logger.info("Found %d tracks for decade %s", len(tracks), decade)
@@ -25,30 +34,22 @@ def build_decade_mix(core: CoreProxy, decade: str) -> list[Track]:
 
 
 def build_genre_mix(core: CoreProxy, genre: str) -> list[Track]:
-    query = {TrackField.GENRE: [genre]}
-    result = core.library.search(query).get()
-    tracks = _extract_tracks(result)
-    logger.info("Found %d tracks for genre %s", len(tracks), genre)
-    return tracks
+    return _search(core, "genre", genre)
 
 
 def build_artist_mix(core: CoreProxy, artist: str) -> list[Track]:
-    query = {TrackField.ARTIST: [artist]}
-    result = core.library.search(query).get()
-    tracks = _extract_tracks(result)
-    logger.info("Found %d tracks for artist %s", len(tracks), artist)
-    return tracks
+    return _search(core, "artist", artist)
 
 
 def build_album_mix(core: CoreProxy, album_uri: str) -> list[Track]:
-    tracks = core.library.lookup([album_uri]).get()
+    tracks = core.library.lookup(cast("list[Uri]", [album_uri])).get()
     flat = _flatten_lookup(tracks)
     logger.info("Found %d tracks for album %s", len(flat), album_uri)
     return flat
 
 
 def build_instant_mix(core: CoreProxy, track_uri: str, limit: int = 50) -> list[Track]:
-    lookup_result = core.library.lookup([track_uri]).get()
+    lookup_result = core.library.lookup(cast("list[Uri]", [track_uri])).get()
     seed_tracks = _flatten_lookup(lookup_result)
     if not seed_tracks:
         logger.warning("No track found for URI: %s", track_uri)
@@ -61,16 +62,14 @@ def build_instant_mix(core: CoreProxy, track_uri: str, limit: int = 50) -> list[
     if seed.genre:
         genres = [g.strip() for g in seed.genre.split("/") if g.strip()]
     if seed.artists:
-        for artist_ref in seed.artists:
-            if artist_ref.name:
-                artists.append(artist_ref.name)
+        artists.extend(a_ref.name for a_ref in seed.artists if a_ref.name)
 
     similar: dict[str, Track] = {}
 
     for genre in genres:
-        query = {TrackField.GENRE: [genre]}
-        result = core.library.search(query).get()
-        for batch in result:
+        g_query = cast("Query[SearchField]", {"genre": [genre]})
+        genre_result = core.library.search(g_query).get()
+        for batch in genre_result:
             for t in batch.tracks:
                 if t.uri and t.uri != track_uri:
                     similar[t.uri] = t
@@ -78,9 +77,9 @@ def build_instant_mix(core: CoreProxy, track_uri: str, limit: int = 50) -> list[
     for artist in artists:
         if len(similar) >= limit:
             break
-        query = {TrackField.ARTIST: [artist]}
-        result = core.library.search(query).get()
-        for batch in result:
+        a_query = cast("Query[SearchField]", {"artist": [artist]})
+        artist_result = core.library.search(a_query).get()
+        for batch in artist_result:
             for t in batch.tracks:
                 if t.uri and t.uri != track_uri:
                     similar[t.uri] = t
@@ -97,16 +96,16 @@ def save_smart_playlist(
     tracks: list[Track],
 ) -> Playlist | None:
     playlist_name = f"{prefix} {name}"
-    uri = f"mopidy:smartplaylists:{_sanitize_name(name)}"
+    uri: str = f"mopidy:smartplaylists:{_sanitize_name(name)}"
 
-    existing = core.playlists.lookup(uri).get()
+    existing = core.playlists.lookup(cast("Uri", uri)).get()
     if existing:
         core.playlists.delete(existing.uri).get()
 
     playlist = Playlist(
         name=playlist_name,
-        uri=uri,
-        tracks=tracks,
+        uri=cast("Uri", uri),
+        tracks=tuple(tracks),
     )
     saved = core.playlists.save(playlist).get()
     logger.info("Saved smart playlist: %s (%d tracks)", playlist_name, len(tracks))
@@ -141,14 +140,14 @@ def refresh_smart_playlists(core: CoreProxy, config_dict: dict) -> None:
                 save_smart_playlist(core, prefix, f"{artist} Mix", tracks)
 
 
-def _extract_tracks(search_result) -> list[Track]:
+def _extract_tracks(search_result: list) -> list[Track]:
     tracks: list[Track] = []
     for batch in search_result:
         tracks.extend(batch.tracks)
     return tracks
 
 
-def _flatten_lookup(lookup_result: dict[str, list[Track]]) -> list[Track]:
+def _flatten_lookup(lookup_result: dict[Uri, list[Track]]) -> list[Track]:
     tracks: list[Track] = []
     for uri_tracks in lookup_result.values():
         tracks.extend(uri_tracks)
diff --git a/src/mopidy_smartplaylists/web.py b/src/mopidy_smartplaylists/web.py
index 80fe666..8252f6d 100644
--- a/src/mopidy_smartplaylists/web.py
+++ b/src/mopidy_smartplaylists/web.py
@@ -1,9 +1,16 @@
+from __future__ import annotations
+
 import json
 import logging
+from typing import TYPE_CHECKING, cast
 
 import tornado.web
-from mopidy.config import Config
-from mopidy.core import CoreProxy
+
+if TYPE_CHECKING:
+    from mopidy_smartplaylists.compat import Config, CoreProxy
+
+if TYPE_CHECKING:
+    from mopidy.models import Playlist
 
 from mopidy_smartplaylists.generators import (
     build_album_mix,
@@ -35,13 +42,15 @@ class DecadeMixHandler(tornado.web.RequestHandler):
             self.write({"playlist": None, "tracks": 0})
             return
         playlist = save_smart_playlist(self.core, self.prefix, f"{decade}s Mix", tracks)
-        self.write({
-            "playlist": {
-                "name": playlist.name if playlist else None,
-                "uri": playlist.uri if playlist else None,
-                "tracks": len(tracks),
-            },
-        })
+        self.write(
+            {
+                "playlist": {
+                    "name": playlist.name if playlist else None,
+                    "uri": playlist.uri if playlist else None,
+                    "tracks": len(tracks),
+                },
+            }
+        )
 
 
 class GenreMixHandler(tornado.web.RequestHandler):
@@ -61,13 +70,15 @@ class GenreMixHandler(tornado.web.RequestHandler):
             self.write({"playlist": None, "tracks": 0})
             return
         playlist = save_smart_playlist(self.core, self.prefix, f"{genre} Mix", tracks)
-        self.write({
-            "playlist": {
-                "name": playlist.name if playlist else None,
-                "uri": playlist.uri if playlist else None,
-                "tracks": len(tracks),
-            },
-        })
+        self.write(
+            {
+                "playlist": {
+                    "name": playlist.name if playlist else None,
+                    "uri": playlist.uri if playlist else None,
+                    "tracks": len(tracks),
+                },
+            }
+        )
 
 
 class ArtistMixHandler(tornado.web.RequestHandler):
@@ -87,13 +98,15 @@ class ArtistMixHandler(tornado.web.RequestHandler):
             self.write({"playlist": None, "tracks": 0})
             return
         playlist = save_smart_playlist(self.core, self.prefix, f"{artist} Mix", tracks)
-        self.write({
-            "playlist": {
-                "name": playlist.name if playlist else None,
-                "uri": playlist.uri if playlist else None,
-                "tracks": len(tracks),
-            },
-        })
+        self.write(
+            {
+                "playlist": {
+                    "name": playlist.name if playlist else None,
+                    "uri": playlist.uri if playlist else None,
+                    "tracks": len(tracks),
+                },
+            }
+        )
 
 
 class AlbumMixHandler(tornado.web.RequestHandler):
@@ -112,15 +125,21 @@ class AlbumMixHandler(tornado.web.RequestHandler):
         if not tracks:
             self.write({"playlist": None, "tracks": 0})
             return
-        name = tracks[0].album.name if tracks[0].album and tracks[0].album.name else "Album"
+        name = (
+            tracks[0].album.name
+            if tracks[0].album and tracks[0].album.name
+            else "Album"
+        )
         playlist = save_smart_playlist(self.core, self.prefix, f"{name} Mix", tracks)
-        self.write({
-            "playlist": {
-                "name": playlist.name if playlist else None,
-                "uri": playlist.uri if playlist else None,
-                "tracks": len(tracks),
-            },
-        })
+        self.write(
+            {
+                "playlist": {
+                    "name": playlist.name if playlist else None,
+                    "uri": playlist.uri if playlist else None,
+                    "tracks": len(tracks),
+                },
+            }
+        )
 
 
 class InstantMixHandler(tornado.web.RequestHandler):
@@ -149,14 +168,18 @@ class InstantMixHandler(tornado.web.RequestHandler):
                     seed_name = t.name
                 break
 
-        playlist = save_smart_playlist(self.core, self.prefix, f"Instant Mix: {seed_name}", tracks)
-        self.write({
-            "playlist": {
-                "name": playlist.name if playlist else None,
-                "uri": playlist.uri if playlist else None,
-                "tracks": len(tracks),
-            },
-        })
+        playlist = save_smart_playlist(
+            self.core, self.prefix, f"Instant Mix: {seed_name}", tracks
+        )
+        self.write(
+            {
+                "playlist": {
+                    "name": playlist.name if playlist else None,
+                    "uri": playlist.uri if playlist else None,
+                    "tracks": len(tracks),
+                },
+            }
+        )
 
 
 class RefreshHandler(tornado.web.RequestHandler):
@@ -176,18 +199,21 @@ class StatusHandler(tornado.web.RequestHandler):
 
     def get(self) -> None:
         result = self.core.playlists.as_list().get()
-        smart = [p for p in result if p.uri and "smartplaylists" in p.uri]
-        self.write({
-            "smart_playlists": [
-                {
-                    "name": p.name,
-                    "uri": p.uri,
-                    "tracks": len(p.tracks) if p.tracks else 0,
-                }
-                for p in smart
-            ],
-            "count": len(smart),
-        })
+        result_typed = cast("list[Playlist]", result)
+        smart = [p for p in result_typed if p.uri and "smartplaylists" in p.uri]
+        self.write(
+            {
+                "smart_playlists": [
+                    {
+                        "name": p.name,
+                        "uri": p.uri,
+                        "tracks": len(p.tracks) if p.tracks else 0,
+                    }
+                    for p in smart
+                ],
+                "count": len(smart),
+            }
+        )
 
 
 def app_factory(config: Config, core: CoreProxy) -> list[tuple]:
diff --git a/tests/test_frontend.py b/tests/test_frontend.py
index 2003f2f..0818728 100644
--- a/tests/test_frontend.py
+++ b/tests/test_frontend.py
@@ -1,5 +1,7 @@
 from unittest import mock
 
+from mopidy.models import Playlist
+
 from mopidy_smartplaylists.frontend import SmartPlaylistsFrontend
 
 
@@ -14,11 +16,16 @@ class TestSmartPlaylistsFrontend:
             "refresh_interval": "0",
         }
         core = mock.Mock()
+        core.library.search.return_value.get.return_value = []
+        core.playlists.lookup.return_value.get.return_value = None
+        core.playlists.save.return_value.get.return_value = Playlist(
+            name="test", uri="dummy:pl", tracks=[]
+        )
 
         frontend = SmartPlaylistsFrontend(config, core)
         frontend.on_start()
 
-        core.library.search.assert_called()
+        assert core.library.search.call_count == 2
 
     def test_on_start_without_recipes(self):
         config = mock.Mock()
@@ -39,10 +46,16 @@ class TestSmartPlaylistsFrontend:
     def test_playlists_loaded_with_interval(self):
         config = mock.Mock()
         config.get.return_value = {
+            "decades": "1980",
             "playlist_prefix": "[Smart]",
             "refresh_interval": "24",
         }
         core = mock.Mock()
+        core.library.search.return_value.get.return_value = []
+        core.playlists.lookup.return_value.get.return_value = None
+        core.playlists.save.return_value.get.return_value = Playlist(
+            name="test", uri="dummy:pl", tracks=[]
+        )
 
         frontend = SmartPlaylistsFrontend(config, core)
         frontend.playlists_loaded()
diff --git a/tests/test_generators.py b/tests/test_generators.py
index b38e95e..59dd5f4 100644
--- a/tests/test_generators.py
+++ b/tests/test_generators.py
@@ -1,6 +1,5 @@
 from unittest import mock
 
-import pytest
 from mopidy.models import Artist, Playlist, SearchResult, Track
 
 from mopidy_smartplaylists.generators import (
@@ -44,7 +43,10 @@ class TestSanitizeName:
 
 class TestExtractTracks:
     def test_extracts_from_search_results(self):
-        tracks = [Track(uri="dummy:1", name="Track 1"), Track(uri="dummy:2", name="Track 2")]
+        tracks = [
+            Track(uri="dummy:1", name="Track 1"),
+            Track(uri="dummy:2", name="Track 2"),
+        ]
         results = [SearchResult(uri="dummy:search", tracks=tracks)]
         assert _extract_tracks(results) == tracks
 
diff --git a/tests/test_web.py b/tests/test_web.py
index 81e969b..8f4ef34 100644
--- a/tests/test_web.py
+++ b/tests/test_web.py
@@ -1,7 +1,8 @@
 import json
 from unittest import mock
 
-import pytest
+import tornado.testing
+import tornado.web
 from mopidy.models import Playlist, Track
 
 from mopidy_smartplaylists.web import (
@@ -30,9 +31,51 @@ class TestAppFactory:
             assert "core" in kwargs
 
 
+class _HandlerTestBase:
+    def make_app(self, handler_cls, **kwargs):
+        return tornado.web.Application(
+            [
+                (r"/test", handler_cls, kwargs),
+            ]
+        )
+
+    def call_handler(self, handler_cls, method="POST", body=None, **kwargs):
+        app = self.make_app(handler_cls, **kwargs)
+        request = tornado.httputil.HTTPServerRequest(
+            method=method,
+            uri="/test",
+            body=json.dumps(body).encode() if isinstance(body, dict) else body,
+            connection=mock.Mock(),
+            headers=tornado.httputil.HTTPHeaders(),
+        )
+        return handler_cls(app, request, **kwargs)
+
+
 class TestDecadeMixHandler:
-    @pytest.fixture
-    def handler(self):
+    def test_missing_decade_returns_400(self):
+        app = tornado.web.Application(
+            [
+                (
+                    r"/decade",
+                    DecadeMixHandler,
+                    {"core": mock.Mock(), "prefix": "[Smart]"},
+                ),
+            ]
+        )
+        request = tornado.httputil.HTTPServerRequest(
+            method="POST",
+            uri="/decade",
+            body=json.dumps({}).encode(),
+            connection=mock.Mock(),
+            headers=tornado.httputil.HTTPHeaders(),
+        )
+        handler = DecadeMixHandler(app, request, core=mock.Mock(), prefix="[Smart]")
+        handler.set_status = mock.Mock()
+        handler.write = mock.Mock()
+        handler.post()
+        handler.set_status.assert_called_once_with(400)
+
+    def test_success(self):
         core = mock.Mock()
         core.library.search.return_value.get.return_value = [
             mock.Mock(tracks=[Track(uri="dummy:1", name="T")])
@@ -44,70 +87,125 @@ class TestDecadeMixHandler:
             tracks=[Track(uri="dummy:1", name="T")],
         )
 
-        h = DecadeMixHandler(mock.Mock(), mock.Mock(), core=core, prefix="[Smart]")
-        h.request = mock.Mock()
-        h.request.body = json.dumps({"decade": "1980"}).encode()
-        return h
-
-    def test_returns_playlist_info(self, handler):
+        app = tornado.web.Application(
+            [
+                (r"/decade", DecadeMixHandler, {"core": core, "prefix": "[Smart]"}),
+            ]
+        )
+        request = tornado.httputil.HTTPServerRequest(
+            method="POST",
+            uri="/decade",
+            body=json.dumps({"decade": "1980"}).encode(),
+            connection=mock.Mock(),
+            headers=tornado.httputil.HTTPHeaders(),
+        )
+        handler = DecadeMixHandler(app, request, core=core, prefix="[Smart]")
+        handler._transforms = []
         handler.write = mock.Mock()
         handler.post()
         data = handler.write.call_args[0][0]
         assert data["playlist"]["name"] == "[Smart] 1980s Mix"
-        assert data["tracks"] == 1
-
-    def test_missing_decade_returns_400(self):
-        h = DecadeMixHandler(mock.Mock(), mock.Mock(), core=mock.Mock(), prefix="[Smart]")
-        h.request = mock.Mock()
-        h.request.body = json.dumps({}).encode()
-        h.set_status = mock.Mock()
-        h.write = mock.Mock()
-        h.post()
-        h.set_status.assert_called_once_with(400)
+        assert data["playlist"]["tracks"] == 1
 
 
 class TestGenreMixHandler:
     def test_missing_genre_returns_400(self):
-        h = GenreMixHandler(mock.Mock(), mock.Mock(), core=mock.Mock(), prefix="[Smart]")
-        h.request = mock.Mock()
-        h.request.body = json.dumps({}).encode()
-        h.set_status = mock.Mock()
-        h.write = mock.Mock()
-        h.post()
-        h.set_status.assert_called_once_with(400)
+        app = tornado.web.Application(
+            [
+                (
+                    r"/genre",
+                    GenreMixHandler,
+                    {"core": mock.Mock(), "prefix": "[Smart]"},
+                ),
+            ]
+        )
+        request = tornado.httputil.HTTPServerRequest(
+            method="POST",
+            uri="/genre",
+            body=json.dumps({}).encode(),
+            connection=mock.Mock(),
+            headers=tornado.httputil.HTTPHeaders(),
+        )
+        handler = GenreMixHandler(app, request, core=mock.Mock(), prefix="[Smart]")
+        handler.set_status = mock.Mock()
+        handler.write = mock.Mock()
+        handler.post()
+        handler.set_status.assert_called_once_with(400)
 
 
 class TestArtistMixHandler:
     def test_missing_artist_returns_400(self):
-        h = ArtistMixHandler(mock.Mock(), mock.Mock(), core=mock.Mock(), prefix="[Smart]")
-        h.request = mock.Mock()
-        h.request.body = json.dumps({}).encode()
-        h.set_status = mock.Mock()
-        h.write = mock.Mock()
-        h.post()
-        h.set_status.assert_called_once_with(400)
+        app = tornado.web.Application(
+            [
+                (
+                    r"/artist",
+                    ArtistMixHandler,
+                    {"core": mock.Mock(), "prefix": "[Smart]"},
+                ),
+            ]
+        )
+        request = tornado.httputil.HTTPServerRequest(
+            method="POST",
+            uri="/artist",
+            body=json.dumps({}).encode(),
+            connection=mock.Mock(),
+            headers=tornado.httputil.HTTPHeaders(),
+        )
+        handler = ArtistMixHandler(app, request, core=mock.Mock(), prefix="[Smart]")
+        handler.set_status = mock.Mock()
+        handler.write = mock.Mock()
+        handler.post()
+        handler.set_status.assert_called_once_with(400)
 
 
 class TestAlbumMixHandler:
     def test_missing_uri_returns_400(self):
-        h = AlbumMixHandler(mock.Mock(), mock.Mock(), core=mock.Mock(), prefix="[Smart]")
-        h.request = mock.Mock()
-        h.request.body = json.dumps({}).encode()
-        h.set_status = mock.Mock()
-        h.write = mock.Mock()
-        h.post()
-        h.set_status.assert_called_once_with(400)
+        app = tornado.web.Application(
+            [
+                (
+                    r"/album",
+                    AlbumMixHandler,
+                    {"core": mock.Mock(), "prefix": "[Smart]"},
+                ),
+            ]
+        )
+        request = tornado.httputil.HTTPServerRequest(
+            method="POST",
+            uri="/album",
+            body=json.dumps({}).encode(),
+            connection=mock.Mock(),
+            headers=tornado.httputil.HTTPHeaders(),
+        )
+        handler = AlbumMixHandler(app, request, core=mock.Mock(), prefix="[Smart]")
+        handler.set_status = mock.Mock()
+        handler.write = mock.Mock()
+        handler.post()
+        handler.set_status.assert_called_once_with(400)
 
 
 class TestInstantMixHandler:
     def test_missing_uri_returns_400(self):
-        h = InstantMixHandler(mock.Mock(), mock.Mock(), core=mock.Mock(), prefix="[Smart]")
-        h.request = mock.Mock()
-        h.request.body = json.dumps({}).encode()
-        h.set_status = mock.Mock()
-        h.write = mock.Mock()
-        h.post()
-        h.set_status.assert_called_once_with(400)
+        app = tornado.web.Application(
+            [
+                (
+                    r"/instant-mix",
+                    InstantMixHandler,
+                    {"core": mock.Mock(), "prefix": "[Smart]"},
+                ),
+            ]
+        )
+        request = tornado.httputil.HTTPServerRequest(
+            method="POST",
+            uri="/instant-mix",
+            body=json.dumps({}).encode(),
+            connection=mock.Mock(),
+            headers=tornado.httputil.HTTPHeaders(),
+        )
+        handler = InstantMixHandler(app, request, core=mock.Mock(), prefix="[Smart]")
+        handler.set_status = mock.Mock()
+        handler.write = mock.Mock()
+        handler.post()
+        handler.set_status.assert_called_once_with(400)
 
 
 class TestRefreshHandler:
@@ -116,12 +214,22 @@ class TestRefreshHandler:
         config.get.return_value = {"playlist_prefix": "[Smart]"}
         core = mock.Mock()
 
-        h = RefreshHandler(mock.Mock(), mock.Mock(), core=core, config=config)
-        h.request = mock.Mock()
-        h.request.body = b"{}"
-        h.write = mock.Mock()
-        h.post()
-        assert h.write.call_args[0][0] == {"status": "ok"}
+        app = tornado.web.Application(
+            [
+                (r"/refresh", RefreshHandler, {"core": core, "config": config}),
+            ]
+        )
+        request = tornado.httputil.HTTPServerRequest(
+            method="POST",
+            uri="/refresh",
+            body=b"{}",
+            connection=mock.Mock(),
+            headers=tornado.httputil.HTTPHeaders(),
+        )
+        handler = RefreshHandler(app, request, core=core, config=config)
+        handler.write = mock.Mock()
+        handler.post()
+        assert handler.write.call_args[0][0] == {"status": "ok"}
 
 
 class TestStatusHandler:
@@ -140,9 +248,21 @@ class TestStatusHandler:
             ),
         ]
 
-        h = StatusHandler(mock.Mock(), mock.Mock(), core=core)
-        h.write = mock.Mock()
-        h.get()
-        data = h.write.call_args[0][0]
+        app = tornado.web.Application(
+            [
+                (r"/status", StatusHandler, {"core": core}),
+            ]
+        )
+        request = tornado.httputil.HTTPServerRequest(
+            method="GET",
+            uri="/status",
+            body=None,
+            connection=mock.Mock(),
+            headers=tornado.httputil.HTTPHeaders(),
+        )
+        handler = StatusHandler(app, request, core=core)
+        handler.write = mock.Mock()
+        handler.get()
+        data = handler.write.call_args[0][0]
         assert data["count"] == 1
         assert data["smart_playlists"][0]["name"] == "[Smart] Jazz Mix"