Scalatest

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Scalatest 中有什么东西可以让我通过 println 语句测试标准输出的输出吗?

Is there something in Scalatest that will allow me to test the output to the standard out via a println statement?

到目前为止，我主要使用 FunSuite with ShouldMatchers.

So far I've mainly been using FunSuite with ShouldMatchers.

例如我们如何检查

object Hi { def hello() { println("hello world") } }

推荐答案

在控制台上测试打印语句的常用方法是稍微不同地构建您的程序，以便您可以拦截这些语句.例如，您可以引入 Output 特征:

The usual way to test print statements on the console is to structure your program a bit differently so that you can intercept those statements. You can for example introduce an Output trait:

trait Output { def print(s: String) = Console.println(s) } class Hi extends Output { def hello() = print("hello world") }

并且在您的测试中，您可以定义另一个特征 MockOutput 实际上拦截调用:

And in your tests you can define another trait MockOutput actually intercepting the calls:

trait MockOutput extends Output { var messages: Seq[String] = Seq() override def print(s: String) = messages = messages :+ s } val hi = new Hi with MockOutput hi.hello() hi.messages should contain("hello world")