In mosts tests, the external variable $input-context is bound to a document, with the input-file element specifying the specific XML file to parse.

In some tests in the SeqDocFunc group, such as fn-doc-5, it appears that the tests expect that the $input-context be bound to URI.  Of course a document can be atomized to yield a string that can be used as a URI, but the document(s) in question (such as TestSources/works-mod.xml) don't seem to contain a valid URI.

I don't see any difference in the input-file element or the query itself to let me guess how the $input-context is to be bound.