Question

我已经使用Lists创建了Gen.oneOf(List[T])以及相应类型的一些外部Scalacheck生成器。我认为返回一个空值的占位符偶尔会有用。目前列表已填充。我该怎么办呢？我是否尝试将空类型附加到列表的末尾？如果是这样我该怎么办呢？如果没有，我怎么能让我的生成器添加一个空值。这看起来很简单，但我现在无法搞清楚。

import org.scalatest.FlatSpec
import org.scalacheck.Gen
import org.scalacheck.Prop.exists
import org.scalatest.prop.PropertyChecks

class EventFieldGeneratorTest extends FlatSpec with PropertyChecks {
  behavior of "Gen.option"
  it should "occasionally return None" in {
    val colors = Gen.oneOf("Blue", "Red", "Green", "Yellow")
    val opt = Gen.option(colors)
    val list = Gen.listOfN(20, opt)
    val p1 = exists(list)(_ == None)
    p1.check
  }
}

有人可以解释为什么我的测试放弃了吗？

Testing started at 10:31 AM ... ! Gave up after only 0 passed tests. 501 tests were discarded.

Process finished with exit code 0

如何将其标记为ScalaTest的失败结果？我使用Flatspec是不是一个坏主意？

也许我应该使用check以外的其他东西......

这是我用来对其进行排序的文档。在Scalatest页面上：

http://www.scalatest.org/user_guide/writing_scalacheck_style_properties

Answer 1

我不认为尝试使用带有可选值的列表存在任何缺陷。您只是遇到了一些问题，这些问题会给您带来麻烦。

令人困惑，但如果您正在使用Scalatest框架，则需要使用Scalatest基础结构来使用Scalacheck。因此，您需要使用Scalatest匹配器，并编写Scalatest风格的属性（使用它forAll），但您仍然会直接使用Scalacheck的生成器。

由于某种原因，列表与Option类型之间的类型推断会给您带来麻烦。如果您使用shouldBe匹配器，

x shouldBe(None)

您将从Scalatest获得相关的运行时错误：

[info] - should occasionally return None *** FAILED ***
[info]   TestFailedException was thrown during property evaluation.
[info]     Message: List() was not equal to None
[info]     Location: (GenTest.scala:13)
[info]     Occurred when passed generated values (
[info]       arg0 = List() // 5 shrinks
[info]     )
[info] Run completed in 1 second, 621 milliseconds.
[info] Total number of tests run: 1
[info] Suites: completed 1, aborted 0
[info] Tests: succeeded 0, failed 1, canceled 0, ignored 0, pending 0

您不应该将列表与Option类型匹配。你需要与Scalatest＆＃34;容器匹配＆＃34;匹配器should contain

import org.scalatest.FlatSpec
import org.scalatest.Matchers
import org.scalacheck.Gen
import org.scalatest.prop.PropertyChecks

class EventFieldGeneratorTest extends FlatSpec with Matchers with PropertyChecks {
  behavior of "Gen.option"
  it should "occasionally return None" in {
    val colors = Gen.oneOf("Blue","Red","Green","Yellow")
    val opt = Gen.option(colors)
    val list = Gen.listOfN(20,opt)
    forAll(list) { (xs: List[Option[String]]) =>
      xs should contain (None)
    }
  }
}

这为您提供了成功的财产检查：

[info] EventFieldGeneratorTest:
[info] Gen.option
[info] - should occasionally return None
[info] ScalaTest
[info] Run completed in 1 second, 9 milliseconds.
[info] Total number of tests run: 1
[info] Suites: completed 1, aborted 0
[info] Tests: succeeded 1, failed 0, canceled 0, ignored 0, pending 0
[info] All tests passed.
[info] Passed: Total 1, Failed 0, Errors 0, Passed 1

有关Scalatest匹配器的更多信息

http://www.scalatest.org/user_guide/using_matchers

在Scalatest中属性检查失败

1 个答案: