prompt test Python

You are an expert in Python testing. Help me implement comprehensive testing strategies using pytest and modern testing best practices. ## Core Testing Patterns ### 1. Basic pytest Tests ```python import pytest def test_function_returns_expected_value(): result = my_function(input_data) assert result == expected_output def test_function_raises_exception(): with pytest.raises(ValueError): my_function(invalid_input) ``` ### 2. Fixtures (Setup/Teardown) ```python @pytest.fixture def sample_data(): return {"key": "value", "count": 42} @pytest.fixture(scope="module") def database_connection(): conn = create_connection() yield conn conn.close() def test_with_fixture(sample_data): assert sample_data["count"] == 42 ``` ### 3. Parameterized Tests ```python @pytest.mark.parametrize("input,expected", [ (1, 2), (2, 4), (3, 6), ]) def test_double(input, expected): assert double(input) == expected ``` ### 4. Mocking External Dependencies ```python from unittest.mock import Mock, patch @patch('module.external_api') def test_api_call(mock_api): mock_api.return_value = {"status": "ok"} result = my_function() assert result["status"] == "ok" mock_api.assert_called_once() ``` ### 5. Async Testing ```python import pytest @pytest.mark.asyncio async def test_async_function(): result = await async_operation() assert result is not None ``` ### 6. Temporary Files ```python def test_file_operations(tmp_path): test_file = tmp_path / "test.txt" test_file.write_text("content") assert test_file.read_text() == "content" ``` ### 7. Property-Based Testing (Hypothesis) ```python from hypothesis import given, strategies as st @given(st.integers(), st.integers()) def test_addition_commutative(a, b): assert add(a, b) == add(b, a) ``` ## Best Practices 1. **AAA Pattern**: Arrange-Act-Assert 2. **Descriptive Names**: `test_should_return_error_when_input_invalid` 3. **Test Isolation**: Each test independent 4. **Use Fixtures**: For shared setup/teardown 5. **Mock External**: Database, APIs, file system 6. **Parametrize**: For multiple input scenarios 7. **Cover Edge Cases**: Empty, null, boundary values ## conftest.py ```python # Shared fixtures across test files @pytest.fixture(scope="session") def app_config(): return load_test_config() ```