Question 1

How to compare two XML files in Java tests using XMLUnit?

Accepted Answer

Use the fluent DiffBuilder API: Diff d = DiffBuilder.compare(Input.fromFile("expected.xml")).withTest(Input.fromString(actualXml)).build(); then assert !d.hasDifferences(). This provides detailed control over comparisons, as shown in the README examples.

Question 2

XMLUnit vs JUnit's XML assertions: which should I use?

Accepted Answer

XMLUnit is more comprehensive for complex XML testing, offering schema validation and XPath evaluation, while JUnit's built-in tools are lighter. Choose XMLUnit if you need detailed comparisons or validation; stick with JUnit for simple, framework-integrated assertions.

Question 3

How to validate XML against a schema with XMLUnit?

Accepted Answer

Create a Validator instance with Validator.forLanguage(Languages.W3C_XML_SCHEMA_NS_URI), set schema sources, and call validateInstance. The README shows an example using Input.fromFile for local schemas, returning a ValidationResult with problem details.

Question 4

What are the differences between xmlunit-assertj and xmlunit-assertj3 modules?

Accepted Answer

xmlunit-assertj is based on AssertJ 2.x and uses reflection for compatibility, but has OSGi issues. xmlunit-assertj3 requires AssertJ 3.18.1+ and throws Open Test Alliance exceptions, better suiting JUnit 5. The README explains this split and its implications.

Question 5

Can I use XMLUnit with Hamcrest matchers?

Accepted Answer

Yes, XMLUnit includes Hamcrest matchers like CompareMatcher and HasXPathMatcher. Import them statically, as shown in the README, to integrate seamlessly into Hamcrest-based tests for assertions on XML identity or XPath values.

Question 6

How to migrate from XMLUnit 1.x to 2.x?

Accepted Answer

Use the legacy module that provides a compatibility layer, but note it's a complete rewrite with no code sharing. Refer to the user guide for migration steps, as the README mentions legacy support but advises checking documentation for details.

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