fix: Update CI tests for new unified examples interface

- Rename test_main_cli.py to test_document_rag.py
- Update all references from main_cli_example.py to document_rag.py
- Update tests/README.md documentation

The tests now properly test the new unified interface while maintaining
the same test coverage and functionality.

tests/test_document_rag.py

@@ -0,0 +1,120 @@
+"""
+Test document_rag (formerly main_cli_example) functionality using pytest.
+"""
+
+import os
+import subprocess
+import sys
+import tempfile
+from pathlib import Path
+
+import pytest
+
+
+@pytest.fixture
+def test_data_dir():
+    """Return the path to test data directory."""
+    return Path("examples/data")
+
+
+@pytest.mark.skipif(
+    os.environ.get("CI") == "true", reason="Skip model tests in CI to avoid MPS memory issues"
+)
+def test_document_rag_simulated(test_data_dir):
+    """Test document_rag with simulated LLM."""
+    with tempfile.TemporaryDirectory() as temp_dir:
+        # Use a subdirectory that doesn't exist yet to force index creation
+        index_dir = Path(temp_dir) / "test_index"
+        cmd = [
+            sys.executable,
+            "examples/document_rag.py",
+            "--llm",
+            "simulated",
+            "--embedding-model",
+            "facebook/contriever",
+            "--embedding-mode",
+            "sentence-transformers",
+            "--index-dir",
+            str(index_dir),
+            "--data-dir",
+            str(test_data_dir),
+            "--query",
+            "What is Pride and Prejudice about?",
+        ]
+
+        env = os.environ.copy()
+        env["HF_HUB_DISABLE_SYMLINKS"] = "1"
+        env["TOKENIZERS_PARALLELISM"] = "false"
+
+        result = subprocess.run(cmd, capture_output=True, text=True, timeout=600, env=env)
+
+        # Check return code
+        assert result.returncode == 0, f"Command failed: {result.stderr}"
+
+        # Verify output
+        output = result.stdout + result.stderr
+        assert "Leann index built at" in output or "Using existing index" in output
+        assert "This is a simulated answer" in output
+
+
+@pytest.mark.skipif(not os.environ.get("OPENAI_API_KEY"), reason="OpenAI API key not available")
+def test_document_rag_openai(test_data_dir):
+    """Test document_rag with OpenAI embeddings."""
+    with tempfile.TemporaryDirectory() as temp_dir:
+        # Use a subdirectory that doesn't exist yet to force index creation
+        index_dir = Path(temp_dir) / "test_index_openai"
+        cmd = [
+            sys.executable,
+            "examples/document_rag.py",
+            "--llm",
+            "simulated",  # Use simulated LLM to avoid GPT-4 costs
+            "--embedding-model",
+            "text-embedding-3-small",
+            "--embedding-mode",
+            "openai",
+            "--index-dir",
+            str(index_dir),
+            "--data-dir",
+            str(test_data_dir),
+            "--query",
+            "What is Pride and Prejudice about?",
+        ]
+
+        env = os.environ.copy()
+        env["TOKENIZERS_PARALLELISM"] = "false"
+
+        result = subprocess.run(cmd, capture_output=True, text=True, timeout=600, env=env)
+
+        assert result.returncode == 0, f"Command failed: {result.stderr}"
+
+        # Verify cosine distance was used
+        output = result.stdout + result.stderr
+        assert any(
+            msg in output
+            for msg in [
+                "distance_metric='cosine'",
+                "Automatically setting distance_metric='cosine'",
+                "Using cosine distance",
+            ]
+        )
+
+
+def test_document_rag_error_handling(test_data_dir):
+    """Test document_rag with invalid parameters."""
+    with tempfile.TemporaryDirectory() as temp_dir:
+        cmd = [
+            sys.executable,
+            "examples/document_rag.py",
+            "--llm",
+            "invalid_llm_type",
+            "--index-dir",
+            temp_dir,
+            "--data-dir",
+            str(test_data_dir),
+        ]
+
+        result = subprocess.run(cmd, capture_output=True, text=True, timeout=60)
+
+        # Should fail with invalid LLM type
+        assert result.returncode != 0
+        assert "Unknown LLM type" in result.stderr or "invalid_llm_type" in result.stderr