定义`Task`用`Task`在SBT设置0.13.13

Question

我试图用SBT 0.13.13

task <<= 
(streams in Test, 
    loadedTestFrameworks in Test, 
    testLoader in Test, 
    testGrouping in Test in test, 
    testExecution in Test in task, 
    fullClasspath in Test in test, 
    javaHome in test) flatMap Defaults.allTestGroupsTask 


warning: `<<=` operator is deprecated. 
    Use `key := { x.value }` or `key ~= (old => { newValue })`. 
    See http://www.scala-sbt.org/0.13/docs/Migrating-from-sbt-012x.html 

的<<=运营商现在已经过时的时候，以消除此设置一个弃用警告，但我不知道如何重写上面的表达式。

我试图把它改写为：

task := Defaults.allTestGroupsTask(
    (streams in Test).value, 
    (loadedTestFrameworks in Test).value, 
    (testLoader in Test).value, 
    (testGrouping in Test in test).value, 
    (testExecution in Test in task).value, 
    (fullClasspath in Test in test).value, 
    (javaHome in test).value) 

但是用我无法分配Task[A]到TaskKey:=

我应该怎么做删除<<=呢？

Answer 1

尝试使用Def.taskDyn：

task := Def.task { 
    Def.task { 
    Defaults.allTestGroupsTask(
     (streams in Test).value, 
     (loadedTestFrameworks in Test).value, 
     (testLoader in Test).value, 
     (testGrouping in Test in test).value, 
     (testExecution in Test in task).value, 
     (fullClasspath in Test in test).value, 
     (javaHome in test).value 
    ) 
    }.value 
}.value