比较单元测试中的scala.xml.Elem对象

Question

我有两个scala.xml.Elem对象(实际的,预期的).我使用的是JUnit 4,但也包含了XMLUnit 1.3.

有没有简单的方法来比较两个对象的相等性,忽略XML中的属性顺序和无关紧要的空格？

我试过XMLUnit.assertXMLEqual(),但它抱怨类型是scala.xml.Elem.

我知道我可以使用equals或==,但我希望断言打印两个值不相等时的好处.如果我使用assertTrue(actual.equals(expected))它们并且它们不相等,则唯一的输出将是"断言失败".

Answer 1

如果要与Elem忽略空格的XML 对象进行比较,可以使用scala.xml.Utility.trim方法从中删除空格.

scala> val a = <foo>bar</foo>
a: scala.xml.Elem = <foo>bar</foo>

scala> val b = <foo>   bar   </foo>
b: scala.xml.Elem = <foo>   bar   </foo>

scala> a == b
res8: Boolean = false

scala> import scala.xml.Utility.trim
import scala.xml.Utility.trim

scala> trim(a) == trim(b)
res9: Boolean = true

如果使用XML文字,Scala不关心属性的顺序:

scala> val a = <foo first="1" second="2" />
a: scala.xml.Elem = <foo first="1" second="2"></foo>

scala> val b = <foo second="1" first="1"  />
b: scala.xml.Elem = <foo first="1" second="1"></foo>

scala> a == b
res22: Boolean = true

我建议您使用ScalaTest进行单元测试ShouldMatchers:

// Scala repl started with scalatest-1.2.jar in the classpath

scala> val a = <foo>bar</foo>
a: scala.xml.Elem = <foo>bar</foo>

scala> val b = <foo>bar</foo>
b: scala.xml.Elem = <foo>bar</foo>

scala> a should equal(b)

scala> val b = <foo>bar2</foo>
b: scala.xml.Elem = <foo>bar2</foo>

scala> a should equal(b)
org.scalatest.TestFailedException: <foo>bar</foo> did not equal <foo>bar2</foo>
    at org.scalatest.matchers.Matchers$class.newTestFailedException(Matchers.scala:148)
    at org.scalatest.matchers.ShouldMatchers$.newTestFailedException(ShouldMatchers.scala:2329)
    at org.scalatest.matchers.ShouldMatchers$ShouldMethodHelper$.shouldMatcher(ShouldMatchers.scala:871)
    at org.scalatest.matchers.ShouldMatchers$SeqShouldWrapper.should(ShouldMatchers.scala:1724)
    at .<init>(<console>:15)
    at .<clinit>(<console>)
    at RequestResult$.<init>(<console>:9)
    at RequestResult$.<clinit>(<console>)
    at RequestResult$scala_repl_result(<console>)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.Delega...

Answer 2

使用assertTrue允许传递自定义消息的版本

public static void assertTrue(java.lang.String message,
                              boolean condition)

和(例如)diff生成具有不相等的下降节点的字符串

scala> val xml1 = <person><name>john</name><lastname>smith</lastname></person>
xml1: scala.xml.Elem = <person><name>john</name><lastname>smith</lastname></person>

scala> val xml2 = <person><name>jane</name><lastname>smith</lastname></person>
xml2: scala.xml.Elem = <person><name>jane</name><lastname>smith</lastname></person>

scala> assert(xml1 == xml2, xml1.child diff xml2.child mkString(", "))
java.lang.AssertionError: assertion failed: <name>john</name>
        at scala.Predef$.assert(Predef.scala:91)
        at .<init>(<console>:8)
        at .<clinit>(<console>)