When talking of included files, people commonly mean included XML in the context of XInclude or external entity references. The SQLUnit include tag represents an unfortunate choice of keyword and does not imply inclusion of external XML files. SQLUnit does not natively support inclusion of external XML files at all. If this functionality is desired, then you can use external entity references or embed XInclude tags and pre-process your test suite with a tool such as XIncluder.
Using External entity references is simple and requires no pre-processing of the test suite. Suppose you wanted to include an XML snippet that predeclares certain common operations that you wish to have executed during the setup phase of each test. The example below shows the declarations you would need to make.
<!DOCTYPE sqlunit SYSTEM "sqlunit.dtd" [ <!ENTITY common-setup SYSTEM "file:tests/common-setup.xml"> ]> <connection... /> <setup> &common-setup; </setup> <test... />
The ENTITY declaration within the DOCTYPE associates the name of the entity with the file name. The entity can then be referenced in the body of the test suite as shown in the setup tag above.
Information on using embedded XInclude tags and using a pre-processor can be found at the XIncluder project. I considered calling XIncluder from within SQLUnit, but that would impose a penalty for everyone, including people who have no interest in including XML files. If you need this functionality, it is easy enough to pre-process the file using a script, and then delete the generated test suite XML file after the test is complete.