Frequently Asked Questions
How it is different from XML Unit?
XMLUnit provides programmatic assertions, whereas this library uses XML
as one big assertion. XML Matcher also allows annotating XML with
Why can't we simply use DTD for XML validator?
DTD is very limited in a way one can define context-specific
constraints. Imagine we have XML that captures directions. We
want to ensure that our template validates that we make exactly two
left turns and then one right turn.
All we can constraint via DTD is
the fact that turn can be either left or right.
<!ELEMENT turn ( left | right )>
Why can't we simply use XML Schema/XSD for XML validator?
XML Schema doesn't have convenient ways of constraining instances of
XML types. For example, imagine that we have XML describing geographic
<xsd:element name="x" type="xsd:double"/>
<xsd:element name="y" type="xsd:double"/>
XSD verifying that one particular occurence of
location contains values close to given above could be written but will
be too bulky.
How it is different from text file comparators?
Text-based comparison tools compare XML documents as plain text files,
ignoring XML specific things like:
- Different forms of empty element ( <abc/> is the same
- Children elements may appear out of order.
What happens when two elements do not match?
It depends on context and current strategy. Matcher may skip elements
that do not have vis-a-vis in template, and try matching with next
template sibling. Matching fails when all possibilities become rejected.
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