Pytest on Flask based API - test by calling the remote API - flask

Question

New to using Pytest on APIs. From my understanding, testing creates another instance of Flask. Additionally, from the tutorials I have seen, they also suggest to create a separate DB table instance to add, fetch and remove data for test purposes. However, I simply plan to use the remote api URL as host to simply make the call.
Now, I set my conftest like this, where the flag --testenv would indicate to make the get/post call on the host listed below:
import pytest
import subprocess
def pytest_addoption(parser):
"""Add option to pass --testenv=api_server to pytest cli command"""
parser.addoption(
"--testenv", action="store", default="exodemo", help="my option: type1 or type2"
)
#pytest.fixture(scope="module")
def testenv(request):
return request.config.getoption("--testenv")
#pytest.fixture(scope="module")
def testurl(testenv):
if testenv == 'api_server':
return 'http://api_url:5000/'
else:
return 'http://locahost:5000'
And my test file is written like this:
import pytest
from app import app
from flask import request
def test_nodes(app):
t_client = app.test_client()
truth = [
{
*body*
}
]
res = t_client.get('/topology/nodes')
print (res)
assert res.status_code == 200
assert truth == json.loads(res.get_data)
I run the code using this:
python3 -m pytest --testenv api_server
The thing I expect is that the test file would simply make a call to the remote api with the creds, fetch the data regardless of how it gets pulled in the remote code, and bring it here for assertion. However, I am getting the 400 BAD REQUEST error, with the error being like this:
assert 400 == 200
E + where 400 = <WrapperTestResponse streamed [400 BAD REQUEST]>.status_code
single_test.py:97: AssertionError
--------------------- Captured stdout call ----------------------
{"timestamp": "2022-07-28 22:11:14,032", "level": "ERROR", "func": "connect_to_mysql_db", "line": 23, "message": "Error connecting to the mysql database (2003, \"Can't connect to MySQL server on 'mysql' ([Errno -3] Temporary failure in name resolution)\")"}
<WrapperTestResponse streamed [400 BAD REQUEST]>
Does this mean that the test file is still trying to lookup the database locally for fetching? I am unable to figure out on which host are they sending the test url as well, so I am kind of stuck here. Looking to get some help around here.
Thanks.