Advanced Topics - eXist: A NoSQL Database and Application Development Platform - page 423

If we send it a document without an id element, it adds an id element for us with
some sort of identifier.
We again modify our id:insert function to insert the additional test case (see the
file id-2.xqm ), as shown in Example 16-4 .
Example 16-4. id.xqm with two test cases (id-2.xqm)
declare
%test:args("<record><id>existing</id></record>")
%test:assertError("id:ERR-PRESENT")
%test:args("<record/>")
%test:assertXPath("$result/exists(id)")
%test:assertXPath("not($result/empty(id))")
function id:insert($record as element(record)) as element(record) {
if($record/id)then
fn:error($id:ERR-PRESENT, "<id> is already present in record!", $record/id)
else
<record>
{
$record/@*,
<id>{id:generate()}</id>,
$record/node()
}
</record>
};
We have added a second %test:args annotation to our function for our second
test case. Every %test:args or set of %test:arg annotations, delimited by one or
more assert annotations, forms a distinct test case.
For this test case we have two assertions—first that the result contains an element
id , and second that the id has some child content. You may have as many asser‐
tions about the result of the function for each test case as you wish.
In this test case we are using %test:assertXPath instead of %test:assertError ,
as before. %test:assertXPath allows us to evaluate an arbitrary XPath expres‐
sion against the $result of the function.
Finally, let's look at how we would add our final test case, which was:
If we send it a document without an id element, it adds an id element for us with
some sort of identifier; otherwise, the result document is indiscernible from the origi‐
nal.
We again modify our id:insert function to add the final test case (see the file
id-3.xqm ), as shown in Example 16-5 .