ScalaCheck:Gen.选择输出超出指定范围的值

作为作业的一部分，我使用Scalacheck查找缺陷。令人难以置信的是，我被卡住了，因为它正在生成一对非零整数

从我的IntelliJ工作表广告逐字记录：

这些零从哪里来？我错过了什么？也许，一些显而易见的事情，但我的眼睛没有抓住它们

我使用的是Scalcheck版本1.12.1

Seq("org.scalacheck" %% "scalacheck" % "1.12.1")

任何帮助，谢谢

更新一：正如@samar所建议的（我在gitbook中也找到了对它的引用），我试图用这样的方法过滤生成器。但运气不太好（代码如下）：

更新二：为了确认，我已经按照Eric的建议做了以下工作：

implicit lazy val genUnequalIntPairs = for {
  i <- Gen.choose(1,1000)
  j <- Gen.choose(i+1,1000)
  if (i != 0 && j != 0)
} yield {
  (i,j)
}

val kk = forAllNoShrink(genUnequalIntPairs)  {
  case (x,y) => println("x =" + x + ", y =" + y)
    x < y
}

kk.check

更新三： FWIW，我发现通过迁移到Scalacheck版本1.13.1（最初是1.12.x），我得到了以下行为：

implicit lazy val genUnequalIntPairs = for {
  i <- Gen.choose(1,1000)
  j <- Gen.choose(1,1000)
  if (i < j)
} yield {
  (i,j)
}

val kk = forAll(genUnequalIntPairs)  {
  case (x,y) => println("x =" + x + ", y =" + y)
    x < y
}

kk.check

但通过将条件从小于更改为相等，会发生以下情况：

implicit lazy val genUnequalIntPairs = for {
  i <- Gen.choose(1,1000)
  j <- Gen.choose(1,1000)
  if (i < j)
} yield {
  (i,j)
}

val kk = forAll(genUnequalIntPairs)  {
  case (x,y) => println("x =" + x + ", y =" + y)
    x == y
}

kk.check

---

显然，应用的条件覆盖了我留给生成器的明确指令。这不是有点不直观吗？其他人怎么想？

这可能是因为房地产的缩水。尝试使用

for allnoshrink

。

我认为这是一个bug，我提出了它：奇怪。你能试试吗：Gen.choose（11000）这样（>0）@Samar，范围意味着谓词，所以实际上不需要。顺便说一下，这也不能解决问题。@Mika'il:是的，我知道这有点可疑。我只是想看看如果我们添加一个额外的保护会发生什么。我在这里又添加了两个测试用例：刚刚尝试过-甚至没有通过第一个测试。如果xfor allnoshrink则不应看到任何

0

值。我仍然认为您遇到了这个问题：。感谢@Samar，确认我的疑问。还有，我接受。埃里克的建议，因为它可以让人摆脱刺激。mikai'l的Github票证包含了我在这里共享的所有测试用例。

x =536, y =730
x =0, y =730
x =0, y =0
x =0, y =365
x =0, y =0
x =0, y =183
x =0, y =0
x =0, y =92
x =0, y =0
x =0, y =46
x =0, y =0
x =0, y =23
x =0, y =0
x =0, y =12
x =0, y =0
x =0, y =6
x =0, y =0
x =0, y =3
x =0, y =0
x =0, y =2
x =0, y =0
x =0, y =1
x =0, y =0
! Falsified after 0 passed tests.
> ARG_0: (0,1)
> ARG_0_ORIGINAL: (536,730)
res0: Unit = ()

implicit lazy val genUnequalIntPairs = for {
  i <- Gen.choose(1,1000)
  j <- Gen.choose(i+1,1000)
  if (i != 0 && j != 0)
} yield {
  (i,j)
}

val kk = forAllNoShrink(genUnequalIntPairs)  {
  case (x,y) => println("x =" + x + ", y =" + y)
    x < y
}

kk.check

x =805, y =1000
x =742, y =926
x =772, y =919
x =219, y =686
x =999, y =1000
x =752, y =792
x =163, y =585
x =721, y =735
x =251, y =866
x =383, y =887
x =797, y =939
x =925, y =947
x =291, y =951
x =502, y =619
x =422, y =756
x =159, y =886
x =49, y =955
x =624, y =819
x =922, y =979
x =881, y =894
x =936, y =952
x =908, y =975
x =802, y =976
x =918, y =946
x =564, y =823
x =544, y =751
x =916, y =938
x =57, y =762
x =614, y =963
x =497, y =986
x =102, y =332
x =264, y =643
x =611, y =720
x =542, y =797
x =704, y =784
Output exceeds cutoff limit.

implicit lazy val genUnequalIntPairs = for {
  i <- Gen.choose(1,1000)
  j <- Gen.choose(1,1000)
  if (i < j)
} yield {
  (i,j)
}

val kk = forAll(genUnequalIntPairs)  {
  case (x,y) => println("x =" + x + ", y =" + y)
    x < y
}

kk.check

x =56, y =752
x =395, y =532
x =468, y =828
x =326, y =749
x =203, y =973
x =294, y =393
x =589, y =975
x =44, y =75
x =406, y =533
x =33, y =381
x =405, y =767
x =13, y =883
x =201, y =341
x =593, y =991
x =636, y =913
x =508, y =782
x =333, y =861
x =306, y =863
x =428, y =537
x =373, y =775
x =74, y =462
x =196, y =299
x =245, y =535
x =312, y =993
x =940, y =989
x =12, y =708

implicit lazy val genUnequalIntPairs = for {
  i <- Gen.choose(1,1000)
  j <- Gen.choose(1,1000)
  if (i < j)
} yield {
  (i,j)
}

val kk = forAll(genUnequalIntPairs)  {
  case (x,y) => println("x =" + x + ", y =" + y)
    x == y
}

kk.check

x =370, y =585
x =0, y =585
x =0, y =0
x =0, y =293
x =0, y =0
x =0, y =147
x =0, y =0
x =0, y =74
x =0, y =0
x =0, y =37
x =0, y =0
x =0, y =19
x =0, y =0
x =0, y =10
x =0, y =0
x =0, y =5
x =0, y =0
x =0, y =3