使用幺半群进行简单的单元测试

Question

假设我测试一个函数 echo: String => String，它只是用 specs2 重复输入。

我可以写一些这样的测试：

class EchoSpec extends SpecificationWithJUnit {

  "echo should handle ASCII alphanumeric names" in {
    echo("abc") must beEqualTo("abc")
  }

  "echo should handle names with slashes" in {
     echo("a/b/c") must beEqualTo("a/b/c")
  }

  "echo should handle names with dots" in {
    echo("a.b.c") must beEqualTo("a.b.c")
  }

  "echo should handle non-ASCII names" in {
    echo("אבג") must beEqualTo("אבג")
  }
}

但是我更愿意摆脱样板代码。所以我正在使用 cats 幺半群：

import cats.implicits._

def testEcho(expected: String): String => Option[String] = {str =>
  if (str == expected) none else s"$str != expected".some
} 

def testEchoes(expected: List[String]): Option[String] = 
  expected foldMap testEcho map (_.mkString(", "))

"echo should handle all names" {
   val expected = List("abc", "a/b/c", "a.b.c", "אבג")
   testEcho(expected) must beNone
}

有意义吗？如何improve/simplify呢？这里真的需要幺半群吗？我可以 git 去掉上面没有幺半群的样板代码吗？

Answer 1

List("abc", "a/b/c", "a.b.c", "אבג")
  .foreach(s => echo(s) must beEqualTo(s))

Answer 2

你也可以使用 ScalaCheck

class EchoSpec extends SpecificationWithJUnit with ScalaCheck {
  "echo should handle all names" >> prop { s: String =>
    echo(s) must beEqualTo(s)
  }
}

使用幺半群进行简单的单元测试

Simple unit testing with monoids

unit-testing

scala

monoids

specs2

scala-cats