Running network based testing experiments require executing the application along with a network emulator in the background in a highly controlled and repeatable manner. It is quite tedious to run the experiments and the network emulation as two separate processes. pynetem addresses this problem for Python based applications on MacOS.
pynetem is a simple Python wrapper library for network emulation on MacOS. It provides wrapper functions based on top of dummynet and packet filter which are the default tools to emulate network link delay, bandwidth and packet loss on MacOS.
Emulating a network link is as easy as applying a decorator to method.
pip install pynetem
Types of emulated links: Incoming, Outgoing, and Duplex
Example: Fetch a webpage with a emulated outgoing network link
# Incoming:
# bandwidth = 3 Mbits/s
# delay = 100 ms
# packet loss percentage = 1 %
@emulate("incoming", bandwidth_in = 3, delay_in = 100, plr_in = 1)
def fetch_page():
resp = req.get("http://www.google.de")
return resp# Outgoing:
# bandwidth = 10 Mbits/s
# delay = 100 ms
# packet loss percentage = 1 %
import requests as req
@emulate("outgoing", bandwidth_out = 10, delay_out = 100, plr_out = 1)
def fetch_page():
resp = req.get("http://www.google.de")
return resp# Duplex:
# incoming bandwidth = 3 Mbits/s
# incoming delay = 15 ms
# incoming packet loss percentage = 1 %
# outgoing bandwidth = 1 Mbits/s
# outgoing delay = 10 ms
# outgoing packet loss percentage = 0.1 %
@emulate("duplex", bandwidth_in = 3, delay_in = 15, plr_in = 1,
bandwidth_out = 1, delay_out = 10, plr_out = 0.1)
def fetch_page():
resp = req.get("http://www.google.de")
return resp