创建用户提示并模拟交互

Question

我有以下代码(为了这个问题我已经简化了)：

  def openFile(directory: File): Try[String] = {
      var input = ""
      do {
        input = readLine("prompt>")
        println("alibaba.txt: 100%")
      } while(input != ":quit")
   }

工作流程是这样的：

用户会得到一个提示：

prompt>

用户编写alibaba，然后按enter键

用户可以看到：

alibaba.txt: 100%
prompt>

一切：

prompt>alibaba
alibaba.txt: 100%
prompt>

现在，我想测试一下它。

我编写了以下代码来测试用户交互：

  test("simulate user input from readline") {
    val prompt = new Prompt()
    prompt.openFile(new File("../resources"))

    val in = new ByteArrayInputStream("alibaba\n".getBytes)
    System.setIn(in)

    val scanner: Scanner = new Scanner(System.in)
    val programResponse: String = scanner.nextLine()
    println("programResponse: " + programResponse)

    System.setIn(System.in)
    assert(programResponse == "alibaba.txt: 100%")
  }

然而，我得到了这个结果，我很困惑：

"alibaba[]" did not equal "alibaba[.txt: 100%]"

那么，如何让测试模拟用户交互呢？

如何读取我的程序所写的内容？

Answer 1

我想你应该以一种简单的可测试的方式来组织你的代码，这意味着你应该将IO提取到更高的抽象中。

出于演示目的，我将您的示例稍微修改为以下代码：

import java.util.Scanner

object YourObject {

  def consoleMethod(in: () => String = new Scanner(System.in).nextLine,
                    out: String => Unit = System.out.println): Unit = {
    var input = ""
    do {
      out("prompt>")
      input = in()
      out("alibaba.txt: 100%")
    } while (input != ":quit")
  }
}

让我们把它分解一下

• in: () => String = new Scanner(System.in).nextLine代表我们的用户输入源。默认情况下，它是System.in.
• out: String => Unit = System.out.println代表我们的输出源。缺省情况下为System.out

让我们测试一下当用户立即进入":quit"时的场景：

import org.scalatest.{Matchers, WordSpec}

class Test extends WordSpec with Matchers {

  "We" should {
    "simulate user input from readline" in {
      var outputs = List.empty[String]
      def accumulate(output: String): Unit = outputs = outputs :+ output

      val in: () => String = () => ":quit"
      val out: String => Unit = accumulate _

      YourObject.consoleMethod(in, out)

      outputs shouldBe List("prompt>", "alibaba.txt: 100%")
    }
  }
}

如果您想要更多的控制，可以使用scalamock

在这种情况下，我们可以模拟、in和out，让它们按照我们需要的方式运行。

val in = mock[() => String]
val out = mock[String => Unit]

设置来源预期：

(in.apply _).expects().anyNumberOfTimes().onCall(_ => ":quit")

现在我们想要设置out来记录我们将要写入的内容：

var outputs = List.empty[String]
def accumulate(output: String): Unit = outputs = outputs :+ output

(out.apply _)
  .expects(new FunctionAdapter1[String, Boolean](_ => true))
  .anyNumberOfTimes()
  .onCall(accumulate _)

太好了，现在让我们设置一下期望：

outputs shouldBe List("prompt>", "alibaba.txt: 100%")

的全部源代码的测试

import org.scalamock.function.FunctionAdapter1
import org.scalamock.scalatest.MockFactory
import org.scalatest.{Matchers, WordSpec}

class Test extends WordSpec with Matchers with MockFactory {

  "We" should {
    "simulate user input from readline" in {
      val in = mock[() => String]
      val out = mock[String => Unit]

      (in.apply _).expects().anyNumberOfTimes().onCall(_ => ":quit")

      var outputs = List.empty[String]

      def accumulate(output: String): Unit = outputs = outputs :+ output

      (out.apply _)
        .expects(new FunctionAdapter1[String, Boolean](_ => true))
        .anyNumberOfTimes()
        .onCall(accumulate _)

      YourObject.consoleMethod(in, out)

      outputs shouldBe List("prompt>", "alibaba.txt: 100%")
    }
  }
}