diff --git a/app/codexchange-cli/tests/conftest.py b/app/codexchange-cli/tests/conftest.py
new file mode 100644
index 0000000..9e9600f
--- /dev/null
+++ b/app/codexchange-cli/tests/conftest.py
@@ -0,0 +1,108 @@
+import pytest
+from unittest.mock import MagicMock
+
+from codexchange.models import Language, ConversionRequest, ConversionResult
+from codexchange.config import ConfigSettings
+
+
+@pytest.fixture
+def sample_python_code():
+    """Sample Python code for testing."""
+    return '''def hello_world():
+    """Print a greeting message."""
+    print("Hello, World!")
+
+# This is a comment
+def add(a, b):
+    """Add two numbers."""
+    return a + b
+'''
+
+
+@pytest.fixture
+def sample_javascript_code():
+    """Sample JavaScript code for testing."""
+    return '''function helloWorld() {
+    // Print a greeting message
+    console.log("Hello, World!");
+}
+
+// This is a comment
+function add(a, b) {
+    return a + b;
+}
+'''
+
+
+@pytest.fixture
+def sample_typescript_code():
+    """Sample TypeScript code for testing."""
+    return '''function helloWorld(): void {
+    // Print a greeting message
+    console.log("Hello, World!");
+}
+
+// This is a comment
+function add(a: number, b: number): number {
+    return a + b;
+}
+'''
+
+
+@pytest.fixture
+def mock_ollama_service():
+    """Mock Ollama service for testing."""
+    mock_service = MagicMock()
+    mock_service.test_connection.return_value = True
+    mock_service.list_models.return_value = []
+    mock_service.generate.return_value = "converted code"
+    return mock_service
+
+
+@pytest.fixture
+def mock_config():
+    """Mock configuration for testing."""
+    return ConfigSettings(
+        ollama_host="http://localhost:11434",
+        default_model="codellama",
+        timeout=300,
+        verbose=False
+    )
+
+
+@pytest.fixture
+def conversion_request(sample_python_code):
+    """Sample conversion request for testing."""
+    return ConversionRequest(
+        source_code=sample_python_code,
+        source_language=Language.PYTHON,
+        target_language=Language.JAVASCRIPT,
+        model="codellama"
+    )
+
+
+@pytest.fixture
+def successful_conversion_result(sample_python_code):
+    """Sample successful conversion result for testing."""
+    return ConversionResult(
+        success=True,
+        converted_code="// Converted from Python\nconsole.log('Hello');",
+        original_code=sample_python_code,
+        source_language=Language.PYTHON,
+        target_language=Language.JAVASCRIPT,
+        model="codellama",
+        syntax_verified=True
+    )
+
+
+@pytest.fixture
+def failed_conversion_result(sample_python_code):
+    """Sample failed conversion result for testing."""
+    return ConversionResult(
+        success=False,
+        original_code=sample_python_code,
+        source_language=Language.PYTHON,
+        target_language=Language.JAVASCRIPT,
+        model="codellama",
+        error_message="Connection failed"
+    )