Big bang testing

There are two approaches to integration testing: big bang testing and incremental testing. With big bang testing, you simply wait until all the components of a system are ready and then start testing. In the case of my service, that meant developing and installing everything, then posting some requests and checking whether the external service could call the internal service, and whether the internal service could access the database and the queue and, not unimportant, give feedback to the external service. Furthermore, of course, I had to test whether the queue triggered the processing service and whether the processing service processed the message correctly too.

In reality, the processing also used the database; it put new messages on the queue and sent emails in case of errors. Additionally, all the components had to access the hard drive for logging to a file (and do not assume the filesystem is always available; the first time on production I actually ran into an Unauthorized Exception and nothing was logged). So that means even more integration testing.