test_main.py

import pytest
from fastapi.testclient import TestClient

from main import MyApp, AppConfig

config = AppConfig.parse_file( "config/config.yaml")

class TestConstructPayload:
    # note we test the function not the endpoint
    def test_happy(self):
        assert MyApp.construct_payload("test", 1, None) == "endpoint called with payload: test 1"


class TestEndpoint:
    def test_endpoint(self):
        my_app = MyApp(config)
        test_app = my_app.build_app()
        with TestClient(test_app) as client:
            response = client.post("/endpoint", json={"string": "test", "integer": 10})
            assert response.status_code == 200
            assert response.json() == {"message": "endpoint called with payload: test 10"}

    def test_endpoint_w_optional_param(self):
        my_app = MyApp(config)
        test_app = my_app.build_app()
        with TestClient(test_app) as client:
            response = client.post("/endpoint", json={"string": "test", "integer": 10, "optional_param": "optional"})
            assert response.status_code == 200
            assert response.json() == {"message": "endpoint called with payload: test 10, optional"}