Is it annoying to work on a product that integrates various web properties? Cause that sounds like a typical Enterprise Integration project that most programme

Is it annoying to work on a product that integrates various web properties? Cause that sounds like a typical Enterprise Integration project that most programmers are dying to escape. Except instead of invoices, payments, they deal with Likes, Tweets, networks. What about test environments of those web properties? do they have one? Is it easy to include unit-test/integration-test?