I wanted to contribute, but spent a few hours to make the (any existing) tests run locally, but didn't succeed.. Followed these docs:
https://github.com/apache/apisix/blob/master/docs/en/latest/internal/testing-framework.md#run-the-test
https://github.com/apache/apisix/blob/master/docs/en/latest/build-apisix-dev-environment-on-mac.md
for me, none of them worked.

Hi @papdaniel, from the description, I didn't know what kind of errors you encountered.

I have two ideas:

1. You can use https://github.com/api7/apisix-plugin-template to write and run test cases.
2. Please take some time to organize the steps, expectations, and errors in details so that I or others can try to help you.

Hello @juzhiyuan!
As I need a simple modification in ip-restriction plugin I'd just add my test cases to t/plugin/ip-restriction.t, and to run I'd go with this https://github.com/apache/apisix/blob/master/docs/en/latest/build-apisix-dev-environment-on-mac.md description which seems quite straightforward with docker. I've done all the steps, and tried to run the test file (first without any modification):
docker exec -it apisix-dev-env prove t/plugin/ip-restriction.t
I'm getting:

t/plugin/ip-restriction.t .. 1/? 
#   Failed test 'ERROR: client socket timed out - t/plugin/ip-restriction.t TEST 1: sanity
# '
#   at /usr/local/share/perl/5.30.0/Test/Nginx/Socket.pm line 2206.

#   Failed test 't/plugin/ip-restriction.t TEST 1: sanity - status code ok'
#   at /usr/local/share/perl/5.30.0/Test/Nginx/Socket.pm line 949.
#          got: ''
#     expected: '200'

#   Failed test 't/plugin/ip-restriction.t TEST 1: sanity - response_body - response is expected (repeated req 0, req 0)'
#   at /usr/local/share/perl/5.30.0/Test/Nginx/Socket.pm line 1660.
#          got: ''
#     expected: '{"message":"Your IP address is not allowed","whitelist":["10.255.254.0/24","192.168.0.0/16"]}
# '
....

ERROR: client socket timed out

Maybe try increasing the timeout configuration in test case.