Add the tests for the service manager

Fix the photo and travel diary relationship to properly work

src/pilgrim/models/photo.py

@@ -25,7 +25,8 @@ class Photo(Base):
         back_populates="photos"
     )
 
-    fk_travel_diary_id = Column(Integer, ForeignKey("travel_diaries.id"),nullable=False)
+    fk_travel_diary_id = Column(Integer, ForeignKey("travel_diaries.id"), nullable=False)
+    travel_diary = relationship("TravelDiary", back_populates="photos")
     __table_args__ = (
         Index('idx_photo_hash_diary', 'hash', 'fk_travel_diary_id'),
     )

src/pilgrim/models/travel_diary.py

@@ -13,6 +13,7 @@ class TravelDiary(Base):
     name = Column(String, nullable=False)
     directory_name = Column(String, nullable=False, unique=True)
     entries = relationship("Entry", back_populates="travel_diary", cascade="all, delete-orphan")
+    photos = relationship("Photo", back_populates="travel_diary", cascade="all, delete-orphan")
 
     __table_args__ = (
         UniqueConstraint('directory_name', name='uq_travel_diary_directory_name'),

tests/service/test_service_manager.py

@@ -0,0 +1,33 @@
+from pilgrim.service.servicemanager import ServiceManager
+from unittest.mock import patch, MagicMock
+
+def test_initial_state_is_none():
+    manager = ServiceManager()
+    assert manager.get_session() is None
+    assert manager.get_entry_service() is None
+    assert manager.get_photo_service() is None
+    assert manager.get_travel_diary_service() is None
+
+@patch('pilgrim.service.servicemanager.TravelDiaryService')
+@patch('pilgrim.service.servicemanager.PhotoService')
+@patch('pilgrim.service.servicemanager.EntryService')
+def test_get_services_instantiates_with_correct_session(
+    mock_entry_service, mock_photo_service, mock_travel_diary_service
+):
+    manager = ServiceManager()
+    mock_session = MagicMock()
+    manager.set_session(mock_session)
+
+    entry_service_instance = manager.get_entry_service()
+    photo_service_instance = manager.get_photo_service()
+    travel_diary_service_instance = manager.get_travel_diary_service()
+
+    mock_entry_service.assert_called_once()
+    mock_photo_service.assert_called_once()
+    mock_travel_diary_service.assert_called_once()
+    mock_entry_service.assert_called_once_with(mock_session)
+    mock_photo_service.assert_called_once_with(mock_session)
+    mock_travel_diary_service.assert_called_once_with(mock_session)
+    assert entry_service_instance == mock_entry_service.return_value
+    assert photo_service_instance == mock_photo_service.return_value
+    assert travel_diary_service_instance == mock_travel_diary_service.return_value