Implement script generation endpoint (Task 18)

- Added ScriptRequest, ScriptResponse, and ScriptSegment Pydantic models
- Created /api/tts/script POST endpoint in main.py
- Integrated with TTSService to generate script segments using AI
- Added generate_script_segments method to TTSService
- Returns segments with unique IDs for frontend tracking
- Handles errors gracefully when AI segmentation fails
- Falls back to pattern-based segmentation when Ollama unavailable
- Added comprehensive tests for the endpoint
- Validates: Requirements 15.1, 15.2

backend/test_script_endpoint.py

@@ -0,0 +1,173 @@
+"""
+Tests for the script generation endpoint.
+"""
+import pytest
+from fastapi.testclient import TestClient
+from main import app
+
+client = TestClient(app)
+
+
+def test_script_endpoint_exists():
+    """Test that the /api/tts/script endpoint exists."""
+    response = client.post(
+        "/api/tts/script",
+        json={
+            "text": "Alice: Hello there!\nBob: Hi Alice!",
+            "roles": ["Alice", "Bob"]
+        }
+    )
+    # Should not return 404
+    assert response.status_code != 404
+
+
+def test_script_generation_with_valid_input():
+    """Test script generation with valid text and roles."""
+    response = client.post(
+        "/api/tts/script",
+        json={
+            "text": "Alice: Hello there!\nBob: Hi Alice, how are you?",
+            "roles": ["Alice", "Bob", "Narrator"]
+        }
+    )
+    
+    assert response.status_code == 200
+    data = response.json()
+    
+    # Check response structure
+    assert "segments" in data
+    assert isinstance(data["segments"], list)
+    assert len(data["segments"]) > 0
+    
+    # Check each segment has required fields
+    for segment in data["segments"]:
+        assert "id" in segment
+        assert "speaker" in segment
+        assert "text" in segment
+        assert isinstance(segment["id"], str)
+        assert isinstance(segment["speaker"], str)
+        assert isinstance(segment["text"], str)
+        assert len(segment["text"]) > 0
+
+
+def test_script_generation_with_empty_text():
+    """Test that empty text returns validation error."""
+    response = client.post(
+        "/api/tts/script",
+        json={
+            "text": "",
+            "roles": ["Alice", "Bob"]
+        }
+    )
+    
+    assert response.status_code == 400
+    data = response.json()
+    assert "error" in data
+    assert data["error"] == "ValidationError"
+
+
+def test_script_generation_with_empty_roles():
+    """Test that empty roles list returns validation error."""
+    response = client.post(
+        "/api/tts/script",
+        json={
+            "text": "Some text here",
+            "roles": []
+        }
+    )
+    
+    assert response.status_code == 400
+    data = response.json()
+    assert "error" in data
+    assert data["error"] == "ValidationError"
+
+
+def test_script_generation_missing_text_field():
+    """Test that missing text field returns validation error."""
+    response = client.post(
+        "/api/tts/script",
+        json={
+            "roles": ["Alice", "Bob"]
+        }
+    )
+    
+    # Our error handler converts 422 to 400
+    assert response.status_code == 400
+    data = response.json()
+    assert "error" in data
+    assert data["error"] == "ValidationError"
+
+
+def test_script_generation_missing_roles_field():
+    """Test that missing roles field returns validation error."""
+    response = client.post(
+        "/api/tts/script",
+        json={
+            "text": "Some text here"
+        }
+    )
+    
+    # Our error handler converts 422 to 400
+    assert response.status_code == 400
+    data = response.json()
+    assert "error" in data
+    assert data["error"] == "ValidationError"
+
+
+def test_script_segments_have_unique_ids():
+    """Test that each segment has a unique ID."""
+    response = client.post(
+        "/api/tts/script",
+        json={
+            "text": "Alice: Hello!\nBob: Hi!\nAlice: How are you?\nBob: Good!",
+            "roles": ["Alice", "Bob"]
+        }
+    )
+    
+    assert response.status_code == 200
+    data = response.json()
+    
+    segment_ids = [seg["id"] for seg in data["segments"]]
+    # Check all IDs are unique
+    assert len(segment_ids) == len(set(segment_ids))
+
+
+def test_script_generation_with_narrator_text():
+    """Test script generation with narrative text (no role markers)."""
+    response = client.post(
+        "/api/tts/script",
+        json={
+            "text": "The sun was setting over the horizon. It was a beautiful evening.",
+            "roles": ["Narrator"]
+        }
+    )
+    
+    assert response.status_code == 200
+    data = response.json()
+    
+    assert len(data["segments"]) > 0
+    # Should assign to Narrator since no role markers
+    assert any(seg["speaker"] == "Narrator" for seg in data["segments"])
+
+
+def test_script_generation_with_mixed_content():
+    """Test script generation with both dialogue and narrative."""
+    response = client.post(
+        "/api/tts/script",
+        json={
+            "text": "The wizard looked into his crystal ball.\nWizard: I see danger approaching.\nThe knight heard the warning.",
+            "roles": ["Wizard", "Narrator"]
+        }
+    )
+    
+    assert response.status_code == 200
+    data = response.json()
+    
+    assert len(data["segments"]) >= 2
+    speakers = [seg["speaker"] for seg in data["segments"]]
+    # Should have both Wizard and Narrator
+    assert "Wizard" in speakers or "Narrator" in speakers
+
+
+if __name__ == "__main__":
+    pytest.main([__file__, "-v"])