diff --git a/requirements-dev.txt b/requirements-dev.txt
index c4b8c9e..6a38ffc 100644
--- a/requirements-dev.txt
+++ b/requirements-dev.txt
@@ -4,4 +4,5 @@ coverage
 mypy
 pylint
 pytest
+pytest-mock~=3.3
 python-dateutil
diff --git a/tests/test_track_loader.py b/tests/test_track_loader.py
new file mode 100644
index 0000000..f56939c
--- /dev/null
+++ b/tests/test_track_loader.py
@@ -0,0 +1,120 @@
+import datetime
+import json
+from pathlib import Path
+from typing import Union, Dict, List
+from unittest.mock import MagicMock
+
+import pytest
+from pytest_mock import MockerFixture
+
+from gpxtrackposter.track_loader import TrackLoader
+from gpxtrackposter.units import Units
+
+
+def mock_activity(mocker: MockerFixture, activity_type: Union[str, list]) -> MagicMock:
+    activity = mocker.MagicMock()
+    activity.type = activity_type
+    return activity
+
+
+@pytest.fixture(name="mock_run_activity")
+def fixture_mock_run_activity(mocker: MockerFixture) -> MagicMock:
+    return mock_activity(mocker, "Run")
+
+
+@pytest.fixture(name="mock_walk_activity")
+def fixture_mock_walk_activity(mocker: MockerFixture) -> MagicMock:
+    return mock_activity(mocker, "Walk")
+
+
+@pytest.fixture(name="mock_hike_activity")
+def fixture_mock_hike_activity(mocker: MockerFixture) -> MagicMock:
+    return mock_activity(mocker, "Hike")
+
+
+def strava_config(tmp_path: Path, activity_type: Union[str, List[str]] = None) -> str:
+    config: Dict[str, Union[str, List[str]]] = {
+        "client_id": "YOUR STRAVA API CLIENT ID",
+        "client_secret": "YOUR STRAVA API CLIENT SECRET",
+        "refresh_token": "YOUR STRAVA REFRESH TOKEN",
+    }
+    if activity_type:
+        config["activity_type"] = activity_type
+    config_json = tmp_path / "strava-config.json"
+    config_json.write_text(json.dumps(config))
+    return str(config_json)
+
+
+@pytest.fixture(name="strava_config_without_type_filter")
+def fixture_strava_config_without_type_filter(tmp_path: Path) -> str:
+    return strava_config(tmp_path)
+
+
+@pytest.fixture(name="strava_config_with_run_type_filter")
+def fixture_strava_config_with_run_type_filter(tmp_path: Path) -> str:
+    return strava_config(tmp_path, "Run")
+
+
+@pytest.fixture(name="strava_config_with_walk_hike_type_filter")
+def fixture_strava_config_with_walk_hike_type_filter(tmp_path: Path) -> str:
+    return strava_config(tmp_path, ["Walk", "Hike"])
+
+
+@pytest.fixture(name="loader")
+def fixture_loader(
+    mocker: MockerFixture, mock_run_activity: MagicMock, mock_walk_activity: MagicMock, mock_hike_activity: MagicMock
+) -> TrackLoader:
+    """Return a :class:`gpxtrackposter.track_loader.TrackLoader` object."""
+    mock_client_class = mocker.patch("gpxtrackposter.track_loader.Client")
+    instance = mock_client_class.return_value
+    instance.get_activities.return_value = [mock_run_activity, mock_walk_activity, mock_hike_activity]
+    return TrackLoader()
+
+
+@pytest.fixture(name="mock_track_instance")
+def fixture_mock_track_instance(mocker: MockerFixture) -> MagicMock:
+    mock_track_class = mocker.patch("gpxtrackposter.track_loader.Track")
+    instance = mock_track_class.return_value
+    instance.length.return_value = 1 * Units().km
+    instance.start_time.return_value = datetime.datetime.now()
+    instance.end_time.return_value = datetime.datetime.now()
+    return instance
+
+
+def test_load_strava_tracks_without_activity_type_filter(
+    loader: TrackLoader,
+    strava_config_without_type_filter: str,
+    mock_track_instance: MagicMock,
+    mock_run_activity: MagicMock,
+    mock_walk_activity: MagicMock,
+    mock_hike_activity: MagicMock,
+) -> None:
+    loader.load_strava_tracks(strava_config_without_type_filter)
+
+    mock_track_instance.load_strava.assert_any_call(mock_run_activity)
+    mock_track_instance.load_strava.assert_any_call(mock_walk_activity)
+    mock_track_instance.load_strava.assert_any_call(mock_hike_activity)
+
+
+def test_load_strava_tracks_with_str_activity_type_filter(
+    loader: TrackLoader,
+    strava_config_with_run_type_filter: str,
+    mock_track_instance: MagicMock,
+    mock_run_activity: MagicMock,
+) -> None:
+    loader.load_strava_tracks(strava_config_with_run_type_filter)
+
+    mock_track_instance.load_strava.assert_called_once_with(mock_run_activity)
+
+
+def test_load_strava_tracks_with_list_activity_type_filter(
+    loader: TrackLoader,
+    strava_config_with_walk_hike_type_filter: str,
+    mock_track_instance: MagicMock,
+    mock_walk_activity: MagicMock,
+    mock_hike_activity: MagicMock,
+) -> None:
+    loader.load_strava_tracks(strava_config_with_walk_hike_type_filter)
+
+    mock_track_instance.load_strava.assert_any_call(mock_walk_activity)
+    mock_track_instance.load_strava.assert_any_call(mock_hike_activity)