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scalaexceptionscalacheck

Rare (intermittent) java.nio.charset.MalformedInputException in ScalaCheck

I'm getting a very rare, but repeatable, MalformedInputException in my ScalaCheck code.

I haven't been able to pin it down perfectly, or get a solid reproduction except "occasionally," but here's the code that I believe is generating the problem:

// Generate varying Unicode characters:
val unicodeCharacter = Gen.choose(Char.MinValue, Char.MaxValue).filter(Character.isDefined)

// Generate varying Unicode strings across all legal characters::
def unicodeGenerator(generator: Gen[Char] = unicodeCharacter, minimum: Int = 5, maximum: Int = 20): Gen[String] = Gen.chooseNum(minimum, maximum).flatMap { n =>
    Gen.sequence[String, Char](List.fill(n)(generator))
}

// The unit test that I think is occasionally blowing up:
"random strings longer than 20 characters" ! prop { (s: String) => { s.length > 20 must beTrue } }.setGen(unicodeGenerator(unicodeCharacter, 21, 30))

And here's the exception that I've seen:

Exception in thread "Thread-391" java.nio.charset.MalformedInputException: Input length = 1
    at java.nio.charset.CoderResult.throwException(CoderResult.java:281)
    at sun.nio.cs.StreamEncoder.implWrite(StreamEncoder.java:285)
    at sun.nio.cs.StreamEncoder.write(StreamEncoder.java:125)
    at sun.nio.cs.StreamEncoder.write(StreamEncoder.java:135)
    at java.io.Writer.write(Writer.java:157)
    at scala.xml.XML$.write(XML.scala:108)
    at scala.xml.XML$$anonfun$save$2.apply$mcV$sp(XML.scala:91)
    at scala.xml.XML$$anonfun$save$2.apply(XML.scala:91)
    at scala.xml.XML$$anonfun$save$2.apply(XML.scala:91)
    at scala.util.control.Exception$Catch.apply(Exception.scala:102)
    at scala.xml.XML$.save(XML.scala:90)
    at sbt.JUnitXmlTestsListener.writeSuite(JUnitXmlTestsListener.scala:170)
    at sbt.JUnitXmlTestsListener.endGroup(JUnitXmlTestsListener.scala:159)
    at sbt.React$$anonfun$react$8.apply(ForkTests.scala:133)
    at sbt.React$$anonfun$react$8.apply(ForkTests.scala:133)
    at scala.collection.immutable.List.foreach(List.scala:318)
    at sbt.React.react(ForkTests.scala:133)
    at sbt.ForkTests$$anonfun$mainTestTask$1$Acceptor$2$.run(ForkTests.scala:74)
    at java.lang.Thread.run(Thread.java:745)
Internal error when running tests: sbt.ForkMain$Run$RunAborted: java.net.SocketException: Broken pipe

Anyone have any ideas what is causing it and more important how to reliably prevent it?

Solution

  • When the JUnitXmlTestsListener saves an XML element with XML.save the default encoding that is used is ISO-8859-1. It should use UTF-8 instead.

    You can try to remove the JUnitXmlTestsListener from your build and use specs2 to generate junit-xml reports:

    libraryDependencies += "org.specs2" %% "specs2-junit" % "3.6"

sbt> testOnly *MySpec -- console junitxml