gemini

tests/test_gemini_service.py

@@ -0,0 +1,814 @@
+"""
+Rigorous Tests for Gemini AI Service.
+
+Tests cover:
+1. Initialization & API key handling
+2. Concurrency semaphores
+3. Text generation
+4. Animation prompt generation
+5. Image analysis & editing
+6. Video generation, status checking, downloading
+7. Error handling
+"""
+import pytest
+import asyncio
+import os
+import tempfile
+from unittest.mock import patch, MagicMock, AsyncMock, PropertyMock
+from datetime import datetime
+
+
+# =============================================================================
+# 1. Initialization & Configuration Tests
+# =============================================================================
+
+class TestGeminiServiceInit:
+    """Test GeminiService initialization and configuration."""
+    
+    def test_init_with_explicit_api_key(self):
+        """Service initializes with explicit API key."""
+        with patch('services.gemini_service.genai') as mock_genai:
+            from services.gemini_service import GeminiService
+            
+            service = GeminiService(api_key="test-key-123")
+            
+            assert service.api_key == "test-key-123"
+            mock_genai.Client.assert_called_once_with(api_key="test-key-123")
+    
+    def test_init_with_env_fallback(self):
+        """Service falls back to environment variable for API key."""
+        with patch('services.gemini_service.genai') as mock_genai:
+            with patch.dict(os.environ, {"GEMINI_API_KEY": "env-key-456"}):
+                from services.gemini_service import GeminiService
+                
+                service = GeminiService()
+                
+                assert service.api_key == "env-key-456"
+    
+    def test_init_fails_without_api_key(self):
+        """Service raises error when no API key available."""
+        with patch.dict(os.environ, {}, clear=True):
+            # Remove GEMINI_API_KEY if present
+            os.environ.pop("GEMINI_API_KEY", None)
+            os.environ.pop("GEMINI_API_KEYS", None)
+            
+            from services.gemini_service import get_gemini_api_key
+            
+            with pytest.raises(ValueError, match="Server Authentication Error"):
+                get_gemini_api_key()
+    
+    def test_models_dict_has_required_entries(self):
+        """MODELS dictionary has all required model names."""
+        from services.gemini_service import MODELS
+        
+        assert "text_generation" in MODELS
+        assert "image_edit" in MODELS
+        assert "video_generation" in MODELS
+        assert all(isinstance(v, str) for v in MODELS.values())
+
+
+# =============================================================================
+# 2. Semaphore Concurrency Tests
+# =============================================================================
+
+class TestSemaphoreConcurrency:
+    """Test concurrency control via semaphores."""
+    
+    def test_video_semaphore_respects_limit(self):
+        """Video semaphore uses MAX_CONCURRENT_VIDEOS."""
+        # Reset global
+        import services.gemini_service as gs
+        gs._video_semaphore = None
+        
+        with patch.object(gs, 'MAX_CONCURRENT_VIDEOS', 3):
+            gs._video_semaphore = None  # Reset
+            sem = gs.get_video_semaphore()
+            # Semaphore internal value
+            assert sem._value == 3
+    
+    def test_image_semaphore_respects_limit(self):
+        """Image semaphore uses MAX_CONCURRENT_IMAGES."""
+        import services.gemini_service as gs
+        gs._image_semaphore = None
+        
+        with patch.object(gs, 'MAX_CONCURRENT_IMAGES', 5):
+            gs._image_semaphore = None
+            sem = gs.get_image_semaphore()
+            assert sem._value == 5
+    
+    def test_text_semaphore_respects_limit(self):
+        """Text semaphore uses MAX_CONCURRENT_TEXT."""
+        import services.gemini_service as gs
+        gs._text_semaphore = None
+        
+        with patch.object(gs, 'MAX_CONCURRENT_TEXT', 10):
+            gs._text_semaphore = None
+            sem = gs.get_text_semaphore()
+            assert sem._value == 10
+    
+    def test_semaphores_are_singletons(self):
+        """Calling get_*_semaphore multiple times returns same object."""
+        import services.gemini_service as gs
+        gs._video_semaphore = None
+        gs._image_semaphore = None
+        gs._text_semaphore = None
+        
+        video1 = gs.get_video_semaphore()
+        video2 = gs.get_video_semaphore()
+        assert video1 is video2
+        
+        image1 = gs.get_image_semaphore()
+        image2 = gs.get_image_semaphore()
+        assert image1 is image2
+        
+        text1 = gs.get_text_semaphore()
+        text2 = gs.get_text_semaphore()
+        assert text1 is text2
+
+
+# =============================================================================
+# 3. Text Generation Tests
+# =============================================================================
+
+class TestTextGeneration:
+    """Test generate_text method."""
+    
+    @pytest.mark.asyncio
+    async def test_generate_text_success(self):
+        """generate_text returns text on success."""
+        with patch('services.gemini_service.genai') as mock_genai:
+            from services.gemini_service import GeminiService
+            
+            # Mock response
+            mock_response = MagicMock()
+            mock_response.text = "Generated text response"
+            mock_genai.Client.return_value.models.generate_content.return_value = mock_response
+            
+            service = GeminiService(api_key="test-key")
+            result = await service.generate_text("Hello world")
+            
+            assert result == "Generated text response"
+    
+    @pytest.mark.asyncio
+    async def test_generate_text_with_custom_model(self):
+        """generate_text uses custom model when provided."""
+        with patch('services.gemini_service.genai') as mock_genai:
+            from services.gemini_service import GeminiService
+            
+            mock_response = MagicMock()
+            mock_response.text = "Custom model response"
+            mock_genai.Client.return_value.models.generate_content.return_value = mock_response
+            
+            service = GeminiService(api_key="test-key")
+            result = await service.generate_text("Hello", model="custom-model")
+            
+            # Verify custom model was used
+            call_args = mock_genai.Client.return_value.models.generate_content.call_args
+            assert call_args.kwargs.get('model') == "custom-model"
+    
+    @pytest.mark.asyncio
+    async def test_generate_text_empty_response(self):
+        """generate_text returns empty string for None response."""
+        with patch('services.gemini_service.genai') as mock_genai:
+            from services.gemini_service import GeminiService
+            
+            mock_response = MagicMock()
+            mock_response.text = None
+            mock_genai.Client.return_value.models.generate_content.return_value = mock_response
+            
+            service = GeminiService(api_key="test-key")
+            result = await service.generate_text("Hello")
+            
+            assert result == ""
+    
+    @pytest.mark.asyncio
+    async def test_generate_text_api_error_404(self):
+        """generate_text raises ValueError for 404 error."""
+        with patch('services.gemini_service.genai') as mock_genai:
+            from services.gemini_service import GeminiService
+            
+            mock_genai.Client.return_value.models.generate_content.side_effect = Exception("404 NOT_FOUND")
+            
+            service = GeminiService(api_key="test-key")
+            
+            with pytest.raises(ValueError, match="Model not found"):
+                await service.generate_text("Hello")
+
+
+# =============================================================================
+# 4. Animation Prompt Tests
+# =============================================================================
+
+class TestAnimationPrompt:
+    """Test generate_animation_prompt method."""
+    
+    @pytest.mark.asyncio
+    async def test_generate_animation_prompt_default(self):
+        """generate_animation_prompt uses default prompt."""
+        with patch('services.gemini_service.genai') as mock_genai:
+            with patch('services.gemini_service.types'):
+                from services.gemini_service import GeminiService
+                
+                mock_response = MagicMock()
+                mock_response.text = "Subtle zoom with camera pan"
+                mock_genai.Client.return_value.models.generate_content.return_value = mock_response
+                
+                service = GeminiService(api_key="test-key")
+                result = await service.generate_animation_prompt(
+                    base64_image="base64data",
+                    mime_type="image/jpeg"
+                )
+                
+                assert result == "Subtle zoom with camera pan"
+    
+    @pytest.mark.asyncio
+    async def test_generate_animation_prompt_custom(self):
+        """generate_animation_prompt uses custom prompt when provided."""
+        with patch('services.gemini_service.genai') as mock_genai:
+            with patch('services.gemini_service.types'):
+                from services.gemini_service import GeminiService
+                
+                mock_response = MagicMock()
+                mock_response.text = "Custom animation"
+                mock_genai.Client.return_value.models.generate_content.return_value = mock_response
+                
+                service = GeminiService(api_key="test-key")
+                result = await service.generate_animation_prompt(
+                    base64_image="base64data",
+                    mime_type="image/jpeg",
+                    custom_prompt="Make it dramatic"
+                )
+                
+                assert result == "Custom animation"
+    
+    @pytest.mark.asyncio
+    async def test_generate_animation_prompt_fallback(self):
+        """generate_animation_prompt returns fallback on empty response."""
+        with patch('services.gemini_service.genai') as mock_genai:
+            with patch('services.gemini_service.types'):
+                from services.gemini_service import GeminiService
+                
+                mock_response = MagicMock()
+                mock_response.text = None
+                mock_genai.Client.return_value.models.generate_content.return_value = mock_response
+                
+                service = GeminiService(api_key="test-key")
+                result = await service.generate_animation_prompt(
+                    base64_image="base64data",
+                    mime_type="image/jpeg"
+                )
+                
+                assert result == "Cinematic subtle movement"
+
+
+# =============================================================================
+# 5. Image Analysis Tests
+# =============================================================================
+
+class TestImageAnalysis:
+    """Test analyze_image method."""
+    
+    @pytest.mark.asyncio
+    async def test_analyze_image_success(self):
+        """analyze_image returns analysis text."""
+        with patch('services.gemini_service.genai') as mock_genai:
+            with patch('services.gemini_service.types'):
+                from services.gemini_service import GeminiService
+                
+                mock_response = MagicMock()
+                mock_response.text = "This image shows a sunset over mountains"
+                mock_genai.Client.return_value.models.generate_content.return_value = mock_response
+                
+                service = GeminiService(api_key="test-key")
+                result = await service.analyze_image(
+                    base64_image="base64data",
+                    mime_type="image/jpeg",
+                    prompt="Describe this image"
+                )
+                
+                assert result == "This image shows a sunset over mountains"
+    
+    @pytest.mark.asyncio
+    async def test_analyze_image_empty_response(self):
+        """analyze_image returns empty string for None response."""
+        with patch('services.gemini_service.genai') as mock_genai:
+            with patch('services.gemini_service.types'):
+                from services.gemini_service import GeminiService
+                
+                mock_response = MagicMock()
+                mock_response.text = None
+                mock_genai.Client.return_value.models.generate_content.return_value = mock_response
+                
+                service = GeminiService(api_key="test-key")
+                result = await service.analyze_image(
+                    base64_image="base64data",
+                    mime_type="image/jpeg",
+                    prompt="Describe"
+                )
+                
+                assert result == ""
+
+
+# =============================================================================
+# 6. Image Editing Tests
+# =============================================================================
+
+class TestImageEditing:
+    """Test edit_image method."""
+    
+    @pytest.mark.asyncio
+    async def test_edit_image_returns_data_uri(self):
+        """edit_image returns base64 data URI."""
+        with patch('services.gemini_service.genai') as mock_genai:
+            from services.gemini_service import GeminiService
+            
+            # Create mock response structure
+            mock_inline_data = MagicMock()
+            mock_inline_data.data = "base64imagedata"
+            mock_inline_data.mime_type = "image/png"
+            
+            mock_part = MagicMock()
+            mock_part.inline_data = mock_inline_data
+            
+            mock_content = MagicMock()
+            mock_content.parts = [mock_part]
+            
+            mock_candidate = MagicMock()
+            mock_candidate.content = mock_content
+            
+            mock_response = MagicMock()
+            mock_response.candidates = [mock_candidate]
+            
+            mock_genai.Client.return_value.models.generate_content.return_value = mock_response
+            
+            service = GeminiService(api_key="test-key")
+            result = await service.edit_image(
+                base64_image="input-base64",
+                mime_type="image/jpeg",
+                prompt="Make it colorful"
+            )
+            
+            assert result == "data:image/png;base64,base64imagedata"
+    
+    @pytest.mark.asyncio
+    async def test_edit_image_no_candidates(self):
+        """edit_image raises error when no candidates returned."""
+        with patch('services.gemini_service.genai') as mock_genai:
+            from services.gemini_service import GeminiService
+            
+            mock_response = MagicMock()
+            mock_response.candidates = []
+            mock_genai.Client.return_value.models.generate_content.return_value = mock_response
+            
+            service = GeminiService(api_key="test-key")
+            
+            with pytest.raises(ValueError, match="No candidates returned"):
+                await service.edit_image(
+                    base64_image="input-base64",
+                    mime_type="image/jpeg",
+                    prompt="Edit"
+                )
+    
+    @pytest.mark.asyncio
+    async def test_edit_image_no_image_data(self):
+        """edit_image raises error when no image data in parts."""
+        with patch('services.gemini_service.genai') as mock_genai:
+            from services.gemini_service import GeminiService
+            
+            # Part without inline_data
+            mock_part = MagicMock()
+            mock_part.inline_data = None
+            
+            mock_content = MagicMock()
+            mock_content.parts = [mock_part]
+            
+            mock_candidate = MagicMock()
+            mock_candidate.content = mock_content
+            
+            mock_response = MagicMock()
+            mock_response.candidates = [mock_candidate]
+            
+            mock_genai.Client.return_value.models.generate_content.return_value = mock_response
+            
+            service = GeminiService(api_key="test-key")
+            
+            with pytest.raises(ValueError, match="No image data found"):
+                await service.edit_image(
+                    base64_image="input-base64",
+                    mime_type="image/jpeg",
+                    prompt="Edit"
+                )
+    
+    @pytest.mark.asyncio
+    async def test_edit_image_default_prompt(self):
+        """edit_image uses default prompt when empty."""
+        with patch('services.gemini_service.genai') as mock_genai:
+            with patch('services.gemini_service.types'):
+                from services.gemini_service import GeminiService
+                
+                mock_inline_data = MagicMock()
+                mock_inline_data.data = "base64data"
+                mock_inline_data.mime_type = "image/png"
+                
+                mock_part = MagicMock()
+                mock_part.inline_data = mock_inline_data
+                
+                mock_content = MagicMock()
+                mock_content.parts = [mock_part]
+                
+                mock_candidate = MagicMock()
+                mock_candidate.content = mock_content
+                
+                mock_response = MagicMock()
+                mock_response.candidates = [mock_candidate]
+                
+                mock_genai.Client.return_value.models.generate_content.return_value = mock_response
+                
+                service = GeminiService(api_key="test-key")
+                result = await service.edit_image(
+                    base64_image="input",
+                    mime_type="image/jpeg",
+                    prompt=""  # Empty prompt
+                )
+                
+                assert "data:" in result
+
+
+# =============================================================================
+# 7. Video Generation Tests
+# =============================================================================
+
+class TestVideoGeneration:
+    """Test start_video_generation method."""
+    
+    @pytest.mark.asyncio
+    async def test_start_video_returns_operation_dict(self):
+        """start_video_generation returns operation dictionary."""
+        with patch('services.gemini_service.genai') as mock_genai:
+            with patch('services.gemini_service.types'):
+                from services.gemini_service import GeminiService
+                
+                mock_operation = MagicMock()
+                mock_operation.name = "operations/video-123"
+                mock_operation.done = False
+                
+                mock_genai.Client.return_value.models.generate_videos.return_value = mock_operation
+                
+                service = GeminiService(api_key="test-key")
+                result = await service.start_video_generation(
+                    base64_image="base64data",
+                    mime_type="image/jpeg",
+                    prompt="Animate this"
+                )
+                
+                assert result["gemini_operation_name"] == "operations/video-123"
+                assert result["done"] == False
+                assert result["status"] == "pending"
+    
+    @pytest.mark.asyncio
+    async def test_start_video_completed_immediately(self):
+        """start_video_generation returns completed when done=True."""
+        with patch('services.gemini_service.genai') as mock_genai:
+            with patch('services.gemini_service.types'):
+                from services.gemini_service import GeminiService
+                
+                mock_operation = MagicMock()
+                mock_operation.name = "operations/video-123"
+                mock_operation.done = True
+                
+                mock_genai.Client.return_value.models.generate_videos.return_value = mock_operation
+                
+                service = GeminiService(api_key="test-key")
+                result = await service.start_video_generation(
+                    base64_image="base64data",
+                    mime_type="image/jpeg",
+                    prompt="Animate this"
+                )
+                
+                assert result["status"] == "completed"
+    
+    @pytest.mark.asyncio
+    async def test_start_video_with_params(self):
+        """start_video_generation passes aspect_ratio and resolution."""
+        with patch('services.gemini_service.genai') as mock_genai:
+            with patch('services.gemini_service.types'):
+                from services.gemini_service import GeminiService
+                
+                mock_operation = MagicMock()
+                mock_operation.name = "operations/video-123"
+                mock_operation.done = False
+                
+                mock_genai.Client.return_value.models.generate_videos.return_value = mock_operation
+                
+                service = GeminiService(api_key="test-key")
+                await service.start_video_generation(
+                    base64_image="base64data",
+                    mime_type="image/jpeg",
+                    prompt="Animate",
+                    aspect_ratio="9:16",
+                    resolution="1080p",
+                    number_of_videos=2
+                )
+                
+                # Verify config was passed
+                call_args = mock_genai.Client.return_value.models.generate_videos.call_args
+                assert call_args is not None
+
+
+# =============================================================================
+# 8. Video Status Checking Tests
+# =============================================================================
+
+class TestVideoStatusChecking:
+    """Test check_video_status method."""
+    
+    @pytest.mark.asyncio
+    async def test_check_status_pending(self):
+        """check_video_status returns pending when not done."""
+        with patch('services.gemini_service.genai') as mock_genai:
+            from services.gemini_service import GeminiService
+            
+            mock_operation = MagicMock()
+            mock_operation.done = False
+            mock_operation.error = None
+            
+            mock_genai.Client.return_value.operations.get.return_value = mock_operation
+            
+            service = GeminiService(api_key="test-key")
+            result = await service.check_video_status("operations/video-123")
+            
+            assert result["done"] == False
+            assert result["status"] == "pending"
+    
+    @pytest.mark.asyncio
+    async def test_check_status_completed_with_url(self):
+        """check_video_status returns completed with video URL."""
+        with patch('services.gemini_service.genai') as mock_genai:
+            from services.gemini_service import GeminiService
+            
+            # Build nested mock structure
+            mock_video = MagicMock()
+            mock_video.uri = "https://storage.googleapis.com/video.mp4"
+            
+            mock_generated_video = MagicMock()
+            mock_generated_video.video = mock_video
+            
+            mock_result = MagicMock()
+            mock_result.generated_videos = [mock_generated_video]
+            
+            mock_operation = MagicMock()
+            mock_operation.done = True
+            mock_operation.error = None
+            mock_operation.result = mock_result
+            
+            mock_genai.Client.return_value.operations.get.return_value = mock_operation
+            
+            service = GeminiService(api_key="test-api-key")
+            result = await service.check_video_status("operations/video-123")
+            
+            assert result["done"] == True
+            assert result["status"] == "completed"
+            assert "video_url" in result
+            assert "test-api-key" in result["video_url"]  # API key appended
+    
+    @pytest.mark.asyncio
+    async def test_check_status_operation_error(self):
+        """check_video_status returns failed on operation error."""
+        with patch('services.gemini_service.genai') as mock_genai:
+            from services.gemini_service import GeminiService
+            
+            mock_error = MagicMock()
+            mock_error.message = "Content blocked by policy"
+            
+            mock_operation = MagicMock()
+            mock_operation.done = True
+            mock_operation.error = mock_error
+            
+            mock_genai.Client.return_value.operations.get.return_value = mock_operation
+            
+            service = GeminiService(api_key="test-key")
+            result = await service.check_video_status("operations/video-123")
+            
+            assert result["done"] == True
+            assert result["status"] == "failed"
+            assert "error" in result
+    
+    @pytest.mark.asyncio
+    async def test_check_status_404_expired(self):
+        """check_video_status handles 404 for expired operation."""
+        with patch('services.gemini_service.genai') as mock_genai:
+            from services.gemini_service import GeminiService
+            
+            mock_genai.Client.return_value.operations.get.side_effect = Exception("404 NOT_FOUND")
+            
+            service = GeminiService(api_key="test-key")
+            result = await service.check_video_status("operations/expired-123")
+            
+            assert result["done"] == True
+            assert result["status"] == "failed"
+            assert "expired" in result["error"].lower()
+    
+    @pytest.mark.asyncio
+    async def test_check_status_no_video_uri(self):
+        """check_video_status returns failed when no video URI."""
+        with patch('services.gemini_service.genai') as mock_genai:
+            from services.gemini_service import GeminiService
+            
+            mock_result = MagicMock()
+            mock_result.generated_videos = []  # Empty
+            
+            mock_operation = MagicMock()
+            mock_operation.done = True
+            mock_operation.error = None
+            mock_operation.result = mock_result
+            
+            mock_genai.Client.return_value.operations.get.return_value = mock_operation
+            
+            service = GeminiService(api_key="test-key")
+            result = await service.check_video_status("operations/video-123")
+            
+            assert result["status"] == "failed"
+            assert "safety filters" in result["error"].lower()
+
+
+# =============================================================================
+# 9. Video Download Tests
+# =============================================================================
+
+class TestVideoDownload:
+    """Test download_video method."""
+    
+    @pytest.mark.asyncio
+    async def test_download_video_saves_file(self):
+        """download_video saves file and returns filename."""
+        with patch('services.gemini_service.genai'):
+            from services.gemini_service import GeminiService, DOWNLOADS_DIR
+            
+            with patch('httpx.AsyncClient') as mock_client:
+                mock_response = MagicMock()
+                mock_response.content = b"fake video data"
+                mock_response.raise_for_status = MagicMock()
+                
+                mock_client_instance = AsyncMock()
+                mock_client_instance.get.return_value = mock_response
+                mock_client_instance.__aenter__.return_value = mock_client_instance
+                mock_client_instance.__aexit__.return_value = None
+                mock_client.return_value = mock_client_instance
+                
+                service = GeminiService(api_key="test-key")
+                
+                # Use temp directory
+                with tempfile.TemporaryDirectory() as temp_dir:
+                    with patch.object(
+                        __import__('services.gemini_service', fromlist=['DOWNLOADS_DIR']),
+                        'DOWNLOADS_DIR',
+                        temp_dir
+                    ):
+                        result = await service.download_video(
+                            "https://example.com/video.mp4",
+                            "test-op-123"
+                        )
+                        
+                        assert result == "test-op-123.mp4"
+    
+    @pytest.mark.asyncio
+    async def test_download_video_http_error(self):
+        """download_video raises error on HTTP failure."""
+        with patch('services.gemini_service.genai'):
+            from services.gemini_service import GeminiService
+            
+            with patch('httpx.AsyncClient') as mock_client:
+                mock_client_instance = AsyncMock()
+                mock_client_instance.get.side_effect = Exception("Connection refused")
+                mock_client_instance.__aenter__.return_value = mock_client_instance
+                mock_client_instance.__aexit__.return_value = None
+                mock_client.return_value = mock_client_instance
+                
+                service = GeminiService(api_key="test-key")
+                
+                with pytest.raises(ValueError, match="Failed to download"):
+                    await service.download_video(
+                        "https://example.com/video.mp4",
+                        "test-op-123"
+                    )
+    
+    @pytest.mark.asyncio
+    async def test_download_video_follows_redirects(self):
+        """download_video client is configured to follow redirects."""
+        with patch('services.gemini_service.genai'):
+            from services.gemini_service import GeminiService
+            
+            with patch('httpx.AsyncClient') as mock_client:
+                mock_response = MagicMock()
+                mock_response.content = b"video data"
+                mock_response.raise_for_status = MagicMock()
+                
+                mock_client_instance = AsyncMock()
+                mock_client_instance.get.return_value = mock_response
+                mock_client_instance.__aenter__.return_value = mock_client_instance
+                mock_client_instance.__aexit__.return_value = None
+                mock_client.return_value = mock_client_instance
+                
+                service = GeminiService(api_key="test-key")
+                
+                with tempfile.TemporaryDirectory() as temp_dir:
+                    with patch('services.gemini_service.DOWNLOADS_DIR', temp_dir):
+                        await service.download_video(
+                            "https://example.com/video.mp4",
+                            "redirect-test"
+                        )
+                
+                # Verify follow_redirects=True was passed
+                mock_client.assert_called_with(timeout=120.0, follow_redirects=True)
+
+
+# =============================================================================
+# 10. Error Handling Tests
+# =============================================================================
+
+class TestErrorHandling:
+    """Test _handle_api_error method."""
+    
+    def test_handle_api_error_404(self):
+        """_handle_api_error raises ValueError for 404."""
+        with patch('services.gemini_service.genai'):
+            from services.gemini_service import GeminiService
+            
+            service = GeminiService(api_key="test-key")
+            
+            with pytest.raises(ValueError, match="Model not found"):
+                service._handle_api_error(Exception("Error 404"), "test-model")
+    
+    def test_handle_api_error_not_found(self):
+        """_handle_api_error handles NOT_FOUND in message."""
+        with patch('services.gemini_service.genai'):
+            from services.gemini_service import GeminiService
+            
+            service = GeminiService(api_key="test-key")
+            
+            with pytest.raises(ValueError, match="Model not found"):
+                service._handle_api_error(Exception("NOT_FOUND: resource"), "test-model")
+    
+    def test_handle_api_error_entity_not_found(self):
+        """_handle_api_error handles 'Requested entity was not found'."""
+        with patch('services.gemini_service.genai'):
+            from services.gemini_service import GeminiService
+            
+            service = GeminiService(api_key="test-key")
+            
+            with pytest.raises(ValueError, match="Model not found"):
+                service._handle_api_error(
+                    Exception("Requested entity was not found"),
+                    "test-model"
+                )
+    
+    def test_handle_api_error_bracket_5_pattern(self):
+        """_handle_api_error handles [5, pattern."""
+        with patch('services.gemini_service.genai'):
+            from services.gemini_service import GeminiService
+            
+            service = GeminiService(api_key="test-key")
+            
+            with pytest.raises(ValueError, match="Model not found"):
+                service._handle_api_error(
+                    Exception("Response [5, 'NOT_FOUND']"),
+                    "test-model"
+                )
+    
+    def test_handle_api_error_reraises_other(self):
+        """_handle_api_error re-raises non-404 errors."""
+        with patch('services.gemini_service.genai'):
+            from services.gemini_service import GeminiService
+            
+            service = GeminiService(api_key="test-key")
+            
+            with pytest.raises(RuntimeError, match="Connection timeout"):
+                service._handle_api_error(
+                    RuntimeError("Connection timeout"),
+                    "test-model"
+                )
+
+
+# =============================================================================
+# 11. Downloads Directory Tests
+# =============================================================================
+
+class TestDownloadsDirectory:
+    """Test downloads directory handling."""
+    
+    def test_downloads_dir_exists(self):
+        """DOWNLOADS_DIR is created on module import."""
+        from services.gemini_service import DOWNLOADS_DIR
+        
+        assert os.path.exists(DOWNLOADS_DIR)
+        assert os.path.isdir(DOWNLOADS_DIR)
+    
+    def test_downloads_dir_is_in_project(self):
+        """DOWNLOADS_DIR is within project directory."""
+        from services.gemini_service import DOWNLOADS_DIR
+        
+        assert "downloads" in DOWNLOADS_DIR
+
+
+if __name__ == "__main__":
+    pytest.main([__file__, "-v"])