Compare scala.xml.Elem object in unit test

Question

I have two scala.xml.Elem objects (actual, expected). I am using JUnit 4, but have also included XMLUnit 1.3.

Is there any easy way to compare the two objec

Answer 1

I modified @Nick's code to work with JDom2. In his code, because of how zip works, if expectedXML has trailing elements that are not in actualXML, the test passes. I fixed that bug, and made the comparison of trailing elements optional:

trait XMLTest extends XMLSupport {
  /** Verify that the XMLs are the same, regardless of attribute or element ordering and ignoring whitespace. */
  def assertEqual(actual: Element, expected: Element, ignoreTrailingElements: Boolean=false): Assertion = {
    // depth-first comparison
    def recurse(actual: Element, expected: Element): Assertion = {
      import scala.collection.JavaConverters._
      val actualChildren: Seq[Element] = actual.getChildren.asScala.sortBy(_.getName)
      val expectedChildren: Seq[Element] = expected.getChildren.asScala.sortBy(_.getName)
      (actualChildren zip expectedChildren) foreach { case (actualChild, expectedChild) =>
        recurse(actualChild, expectedChild)
      }
      actual.getName shouldEqual expected.getName
      actual.getTextNormalize shouldEqual expected.getTextNormalize
      actual.getAttributes.asScala.map(_.toString).sorted shouldEqual expected.getAttributes.asScala.map(_.toString).sorted
      if (!ignoreTrailingElements && actualChildren.size < expectedChildren.size) {
        val diff = expectedChildren.drop(actualChildren.size)
        fail("Extra XML children found: " + prettyPrint(diff))
      } else succeed
    }

    recurse(actual, expected)
  }
}

I wrote this trait to mix into the test code:

trait XMLSupport {
  import org.jdom2.output.{Format, XMLOutputter}

  def prettyPrint(doc: Document): String = {
    val xmlOutput = new XMLOutputter()
    xmlOutput.setFormat(Format.getPrettyFormat)
    xmlOutput.outputString(doc)
  }

  def prettyPrint(elements: Seq[Element]): String = {
    import scala.collection.JavaConverters._

    val xmlOutput = new XMLOutputter()
    xmlOutput.setFormat(Format.getPrettyFormat)
    xmlOutput.outputString(elements.asJava)
  }
}

I invoked the test this way:

class XmlTest extends WordSpec with MustMatchers {
  // test code here
  assertEqual(actualXML.getRootElement, expectedXML.getRootElement, ignoreTrailingElements=true)
}