The lwAFTR and associated software is tested in several ways. Igalia uses unit tests, integration tests ("selftest.sh"), end-to-end tests, and does an increasing amount of automated performance analysis with Hydra.
The overall project is developed as a series of smaller, more modular parts. For example, facilities like ARP and ping support are implemented as Snabb apps, independently of the main lwAFTR app; they are then all combined into an app network within Snabb. YANG support has a similar flavour; the majority of it is run in a separate process from the data plane. This makes it easier to test, easier to extend and change, and more reliable.
An example of our testing is how ARP support is tested. It has unit tests (in the function 'selftest()', following the convention to run unit tests automatically), which check how the request is formed, and the reply the library gives to that request. We also have two end-to-end tests for ARP; these specify an incoming packet, pass it through the whole app network, and make sure that the end result is byte for byte identical with what is expected. Both the implementation and the testing were done with careful attention paid to RFC 826 throughout, as well as to dumps of ARP packets from the live network the developer was on.
ARP has two main parts: resolving a remote address, and providing the address of
the lwAFTR on request. The first one can be tested in a network by specifying
only the remote IP of the next IPv4 hop (not the ethernet address), then sending
packets through the lwAFTR and confirming on the remote host that they are
arriving. The latter can be tested by issuing an ARP request to the lwAFTR from
another machine; if the other machine runs Linux, arp -n should then show a
new entry corresponding to the lwAFTR. The end to end tests simulate both of
these cases, but with captured packets rather than a live network.
There are a hierarchy of tests. Unit tests are internally oriented, and make sure that basic functionality and some edge cases are tested. By convention, they are found in functions called selftest().
Integration tests tend to be called selftest.sh, or invoked by selftesh.sh. These test larger components of the system. The end to end tests have IPv4 and IPv6 packet captures, run them through the lwAFTR app network, and compare the results with predetermined captures and counter values, making sure everything works as expected. These test a large variety of RFC-mandated behaviours.
We also have some 'soak tests', which repeatedly do the same thing a large number of times; these show that the system holds up under the tested heavy workloads, without errors like memory corruption or memory leaks, which would cause them to fail.
Igalia is following the lead of upstream Snabb in automated performance testing. This is a work in progress, and can be seen at https://hydra.snabb.co/project/igalia . We are also developing property-based tests to stress-test our yang infrastructure, and have written a load tester for our yang implementation as well, verifying that it is performant.