Simulate connection errors

Question

We've been using protractor for end-to-end testing for a while.

Now we are trying to cover several corner cases, which involve modifying the response from the API endpoint requests - for this we are using protractor-http-mock which provides an easy-to-use way to replace HTTP responses with pre-defined mocks.

But, what if we want to test a situation when a sudden connection loss happens? What are our options in this case?

In other words, we want to achieve a case when requests to specific endpoints would produce a network connection error and see how our application would react.

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I'm open to any suggestions, I am currently thinking of the following strategies:

• see if there are third-party nodejs libraries similar to protractor-http-mock
• mock $http angularjs service
• fire up a proxy and somehow control it during the tests (grunt-connect-proxy looks pretty mature though I'm not sure if it is possible to dynamically change the behavior of the proxy from spec to spec)
• control it on a browser level - e.g. with a Network Throttling google chrome feature (though I'm pretty sure it is something that selenium cannot control, Network throttling with chrome and selenium) (browser addon/extension?)

Answer 1

Seems like the Comcast tool would provide the majority of the functionality you need:

Comcast is a tool designed to simulate common network problems like latency, bandwidth restrictions, and dropped/reordered/corrupted packets.

It works by wrapping up some system tools in a portable(ish) way. On BSD-derived systems such as OSX, we use tools like ipfw and pfctl to inject failure. On Linux, we use iptables and tc. Comcast is merely a thin wrapper around these controls.

https://github.com/tylertreat/Comcast

Example on Linux:

comcast --device=eth0 --latency=250 --target-bw=1000 --default-bw=1000000 --packet-loss=10% --target-addr=8.8.8.8,10.0.0.0/24 --target-proto=tcp,udp,icmp --target-port=80,22,1000:2000

You can change the settings on the fly and put packet loss up to 100% as needed.