Testing Network APIs with pytest

For the past six months, a significant part of my work has been maintaining the company’s website. Since I took over the code midway, there’s always a risk of introducing new bugs during maintenance. Therefore, as required by my supervisor, I learned how to implement automated testing.

The testing framework used is pytest, the most popular testing framework in Python.

The framework is very simple to use. Create files starting with test_, then write functions starting with test_ inside them. Within these functions, write test code and add assert statements to complete the most basic tests:

BASE_URL = 'http://127.0.0.1:4567'

def test_login_success():
    login_data = {"username": "USER", "password": "123456"}
    response = requests.post(f"{BASE_URL}/login", json=login_data)
    
    # Assert key results
    assert response.status_code == 200
    assert "accessToken" in response.json().get("data")

In actual testing, we often need to set up some shared information between different tests. For example, all the APIs I need to test require authentication, so it’s perfect to use pytest’s fixture system. We can first obtain a login token before testing begins, then use the same token to access APIs in each test function:

@pytest.fixture(scope='session')
def prod_admin_auth_header():
    return auth_header("admin", "123456")

def test_get_dictionary_id(prod_admin_auth_header):
    response = requests.get(f"{BASE_URL}/GetDictionaryid", headers=lab_mem_auth_header)
    assert response.status_code == 200

Here, functions marked as fixture can be directly passed into test functions as parameters by their function names, without requiring additional operations.

Additionally, you can create a special file conftest.py in the test folder to store all the fixtures that need to be shared across the entire test suite. This way, in other test files, you can directly use the configured fixtures without manual imports.