org.scalatest.StreamlinedXmlEquality.scala Maven / Gradle / Ivy
/*
* Copyright 2001-2013 Artima, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.scalatest
import scala.xml.{NodeSeq}
import org.scalactic.{Equality, Uniformity}
/**
* Trait providing an implicit Equality[T] for subtypes
* of scala.xml.NodeSeq that before testing for equality, will normalize left and right sides
* by removing empty XML text nodes and trimming non-empty text nodes.
*
*
* Here's an example of some unnormalized XML:
*
*
*
* <summer>
* <day></day>
* <night>
* with lots of stars
* </night>
* </summer>
*
*
*
* Prior to testing it for equality, the implicit Equality[T] provided by this trait would transform
* the above XML to:
*
*
*
* <summer><day></day><night>with lots of stars</night></summer>
*
*
*
* The goal of this trait is to provide an implicit Equality for XML that makes it easier to write tests involving XML.
* White space is significant in XML, and is taken into account by the default equality for XML, accessed
* by invoking the == method on an XML NodeSeq. Here's an example:
*
*
*
* scala> val xmlElem = <summer><day></day><night>with lots of stars</night></summer>
* xmlElem: scala.xml.Elem = <summer><day></day><night>with lots of stars</night></summer>
*
* scala> import org.scalatest.Assertions._
* import org.scalatest.Assertions._
*
* scala> assert(xmlElem === <summer>
* | <day></day>
* | <night>
* | with lots of stars
* | </night>
* | </summer>)
* org.scalatest.exceptions.TestFailedException: <summer><day></day><night>with lots of stars</night></summer> did not equal <summer>
* <day></day>
* <night>
* with lots of stars
* </night>
* </summer>
* at org.scalatest.Assertions$class.newAssertionFailedException(Assertions.scala:500)
* at org.scalatest.Assertions$.newAssertionFailedException(Assertions.scala:1538)
* at org.scalatest.Assertions$AssertionsHelper.macroAssert(Assertions.scala:466)
* ... 53 elided
*
*
*
* The above assertion fails because of whitespace differences in the XML.
* When such whitespace differences are unimportant to the actual application, it can make it
* easier to write readable test code if you can compare XML for equality without taking
* into account empty text nodes, or leading and trailing whitespace in nonempty text nodes.
* This trait provides an Equality[T]
* instance that does just that:
*
*
*
* scala> import org.scalatest.StreamlinedXmlEquality._
* import org.scalatest.StreamlinedXmlEquality._
*
* scala> assert(xmlElem === <summer>
* | <day></day>
* | <night>
* | with lots of stars
* | </night>
* | </summer>)
*
*
* @author Bill Venners
*/
trait StreamlinedXmlEquality {
/**
* Provides an implicit Equality[T]
* instance for any subtype of scala.xml.NodeSeq that, prior for testing
* for equality, will normalize the XML by removing empty text nodes and trimming
* non-empty text nodes.
*
*
* See the main documentation for this trait for more details and examples.
*
*
* @return an Equality[T] instance that normalizes XML before testing for equality
*/
implicit def streamlinedXmlEquality[T <: NodeSeq]: Equality[T] = {
new Equality[T] {
val xu: Uniformity[T] = StreamlinedXml.streamlined[T]
def areEqual(a: T, b: Any): Boolean = {
xu.normalized(a) == xu.normalizedOrSame(b)
}
}
}
}
/**
* Companion object that facilitates the importing of StreamlinedXmlEquality members as
* an alternative to mixing it the trait. One use case is to import StreamlinedXmlEquality members so you can use
* them in the Scala interpreter.
*
* @author Bill Venners
*/
object StreamlinedXmlEquality extends StreamlinedXmlEquality