|The distinction between black box testing and white box testing is one of tester knowledge. b>|
Integration testing is about two parts of the system coming together and testing to ensure there are no "disagreements" between those two parts. The focus in integration testing is more about an idea of risk (the risk of disagreement between systems) than it is about tester knowledge. I can run an integration test as a white box test (testing how two Web services integrate by looking at their message model and how they persist data once they get it) or a black box test (testing how a new version of Adobe Acrobat integrates with the new version of FireFox -– both of which I have no idea how they work).
For more on integration testing, see a similar question I answered about how to approach integration testing and one that John Overbaugh answered about how to do integration testing.
This was first published in November 2008