在另一个线程中重定向标准输出 [英] Redirect stdout in another thread
问题描述
我正在尝试编写一个测试来重定向 main 方法的 stdout
,但似乎一旦我调用了 main,它似乎在另一个线程上启动,我无法捕获输出.代码如下:
I am trying to write a test that will redirect the stdout
of a main method, but it seems that once I call the main, it seems to start on another thread and I cannot capture the output. Here is the code:
这有效:
val baos = new ByteArrayOutputStream
val ps = new PrintStream(baos)
System.setOut(ps)
print("123")
Assert.assertEquals("123", baos.toString)
这不会:
val baos = new ByteArrayOutputStream
val ps = new PrintStream(baos)
System.setOut(ps)
GameRunner.main(_)
Assert.assertEquals("123", baos.toString)
....
object GameRunner {
def main(args: Array[String]) {
print("123")
如何在我的测试中捕获对 print
的调用?
How can I catch the call to print
in my test?
*我也试过 scala.Console.setOut
编辑
我确实注意到,当我不重定向时,运行 GameRunner.main(_)
甚至没有在控制台中列出任何内容.这是什么原因造成的?
I do notice that running GameRunner.main(_)
does not even list anything in the console when I am not redirecting. What is causing this?
推荐答案
print
实际上是 Predef.print
调用 Console.print
.即使您调用 System.setOut
,我也不知道这是否对 Console.print
有影响.尝试调用 Console.setOut
或尝试:
print
is really Predef.print
which calls Console.print
. Even though you call System.setOut
I don't know if that has an impact on Console.print
. Try to call Console.setOut
or try:
Console.withOut(ps)(GameRunner.main(null))
另一种可能性是,通过调用 GameRunner.main(_) 您没有执行任何操作(因为它可能只是返回函数 (args: Array[String]) => GameRunner.main(args)
?.应该很快排除.
The other possibility is that by calling GameRunner.main(_) you are not executing anything (as may be it's just returning the function (args: Array[String]) => GameRunner.main(args)
?. Should be quick to rule that out.
编辑是的:
scala> object A { def main(args: Array[String]) { println("1") } }
defined module A
scala> A.main(null)
1
scala> A.main(_)
res1: Array[String] => Unit = <function1>
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