对于getEngineByName（“JavaScript”），Sbt 0.13 ScriptEngine为空 [英] Sbt 0.13 ScriptEngine is Null for getEngineByName(“JavaScript”)

问题描述

当我在sbt 0.13中运行使用 getEngineByName（JavaScript）的测试时，该方法返回 null 。
安全代码适用于sbt 0.12.x.

When I run tests which use getEngineByName("JavaScript") in sbt 0.13 the method returns null. The safe code works fine with sbt 0.12.x.

尝试在不同的环境：Windows 7和Mac - 同样的问题。

Tried on different environments: Windows 7 and Mac - same problem.

我试图在sbt中手动设置 javaHome 。

I tried to manually set javaHome in sbt.

test：dependencyClasspath 包含 .ivy2 / cache / rhino / js / jars / js -1.6R7.jar

知道什么是错的吗？

推荐答案

哈哈，事实证明我几个月前自己遇到了这个问题，并且忘掉了一切！但后来我在我自己的源代码中发现了这个：

Haha it turns out I had this problem myself a few months ago, and forgot all about it! But then I found this just now in my own source code:

// the (null) became necessary when we upgraded to sbt 0.13. I don't understand why.
// classloaders, go figure! - ST 8/26/13
val engine =
  (new javax.script.ScriptEngineManager(null))
    .getEngineByName("rhino")
    .ensuring(_ != null, "JavaScript engine unavailable")

因此将null传递给ScriptEngineManager构造函数是修复...

So passing null to the ScriptEngineManager constructor is the fix...

...但我不能忽视根本原因，除非我打赌这是一个类加载器的事情。请注意， fork in run：= true 也会使问题消失。

...but I can't shed on any light on the underlying cause, except that I bet it's a classloader thing. Note that fork in run := true also makes the problem go away.

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