test: add unit tests for chat history title generation (57 tests)

- test_title_service.py: 21 tests covering fallback title, AI-generated title,
  singleton factory, edge cases (empty/None/whitespace, agent errors)
- test_cosmos_service.py: 21 tests covering add_message generated_title handling,
  metadata merge preserving titles, title resolution priority chain,
  rename_conversation, delete_all_conversations
- test_app_endpoints.py: 15 tests covering /api/brief/parse and /api/chat title
  generation flow, conversation CRUD (list/rename/delete/delete-all)
- conftest.py: test configuration with env vars setup and sys.path for CI

Author: Shubhangi-Microsoft

content-gen/src/tests/conftest.py

@@ -0,0 +1,81 @@
+"""
+Pytest configuration for Content Generation backend tests.
+
+Adds content-gen/src/backend to sys.path so that imports like
+``from services.title_service import TitleService`` resolve correctly
+when pytest is invoked by the CI workflow from the repo root:
+
+    pytest ./content-gen/src/tests
+"""
+
+import sys
+import os
+import asyncio
+
+# ---- environment setup (BEFORE any backend imports) -----------------------
+# The settings module reads env-vars at import time via pydantic-settings.
+# Set minimal dummy values so that the module can be imported in CI where
+# no .env file or Azure resources exist.
+os.environ.setdefault("AZURE_OPENAI_ENDPOINT", "https://test.openai.azure.com")
+os.environ.setdefault("AZURE_OPENAI_RESOURCE", "test-resource")
+os.environ.setdefault("AZURE_COSMOS_ENDPOINT", "https://test.documents.azure.com:443/")
+os.environ.setdefault("AZURE_COSMOSDB_DATABASE", "test-db")
+os.environ.setdefault("AZURE_COSMOSDB_ACCOUNT", "test-account")
+os.environ.setdefault("AZURE_COSMOSDB_CONVERSATIONS_CONTAINER", "conversations")
+os.environ.setdefault("DOTENV_PATH", "")   # prevent reading a real .env file
+
+import pytest  # noqa: E402  (must come after env setup)
+
+# ---- path setup ----------------------------------------------------------
+# The backend package lives at  <repo>/content-gen/src/backend.
+# We add  <repo>/content-gen/src/backend  so that ``import settings``,
+# ``import services.…``, ``import models``, etc. resolve correctly.
+_THIS_DIR = os.path.dirname(os.path.abspath(__file__))
+_SRC_DIR = os.path.dirname(_THIS_DIR)          # content-gen/src
+_BACKEND_DIR = os.path.join(_SRC_DIR, "backend")  # content-gen/src/backend
+
+for _p in (_SRC_DIR, _BACKEND_DIR):
+    if _p not in sys.path:
+        sys.path.insert(0, _p)
+
+
+# ---- fixtures -------------------------------------------------------------
+
+@pytest.fixture(scope="session")
+def event_loop():
+    """Create an instance of the default event loop for each test session."""
+    loop = asyncio.get_event_loop_policy().new_event_loop()
+    yield loop
+    loop.close()
+
+
+@pytest.fixture
+def sample_creative_brief():
+    """Sample creative brief for testing."""
+    return {
+        "overview": "Summer Sale 2024 Campaign",
+        "objectives": "Increase online sales by 25% during the summer season",
+        "target_audience": "Young professionals aged 25-40 interested in premium electronics",
+        "key_message": "Experience premium quality at unbeatable summer prices",
+        "tone_and_style": "Upbeat, modern, and aspirational",
+        "deliverable": "Social media carousel posts and email banners",
+        "timelines": "Campaign runs June 1 - August 31, 2024",
+        "visual_guidelines": "Use bright summer colors, outdoor settings, lifestyle imagery",
+        "cta": "Shop Now",
+    }
+
+
+@pytest.fixture
+def sample_product():
+    """Sample product for testing."""
+    return {
+        "product_name": "ProMax Wireless Headphones",
+        "category": "Electronics",
+        "sub_category": "Audio",
+        "marketing_description": "Immerse yourself in crystal-clear sound with our flagship wireless headphones.",
+        "detailed_spec_description": "40mm custom drivers, Active Noise Cancellation, 30-hour battery life, Bluetooth 5.2, USB-C fast charging",
+        "sku": "PM-WH-001",
+        "model": "ProMax-2024",
+        "image_url": "https://example.com/images/headphones.jpg",
+        "image_description": "Sleek over-ear headphones in matte black with silver accents",
+    }