Scala Koans 中的 === (triple-equals) 运算符是什么? [英] What is the === (triple-equals) operator in Scala Koans?

问题描述

我开始研究 Scala Koans，它围绕一套单元测试组织，其中包含需要填补的空白(这个想法模仿了一个类似的 Ruby Koans 项目.)你启动 sbt 工具运行一个测试，它警告:

<前>[信息] + *********************************************[信息] +[信息] +[信息] +[信息] + 请沉思AboutEmptyValues"套件的公案无等于无"[信息] +[信息] +[信息] +[信息] + *********************************************

...所以你去看看这个单元测试，它说:

<前>测试(无等于无"){断言(无 === __)}

...而且，在冥想之后，你意识到你应该像这样填空:

<前>测试(无等于无"){断言(无 === 无)}

...然后它继续进行下一个单元测试.

不过，我的问题是这个 === 运算符是什么?我似乎无法在任何地方找到它.这是 Scala Koans 项目本身定义的 DSL 运算符吗?或者它是 ScalaTest 框架的一部分?还是在 Scala 中?

解决方案

这是来自 ScalaTest.看看这个页面:FunSuite 入门.它说:

<块引用>

ScalaTest 允许您使用 Scala 的断言语法，但定义了一个三元组等于运算符 (===) 为您提供更好的错误消息.以下代码会给你一个错误，表明断言失败:

assert(1 == 2)

改用三重等于会给你提供更多信息的错误消息，1 不等于 2":

assert(1 === 2)

I started working my way through the Scala Koans, which is organized around a suite of unit tests with blanks that one needs to fill in. (This idea was modeled after a similar Ruby Koans project.) You start the sbt tool running a test, and it admonishes:

[info]   + ***************************************** 
[info]   +  
[info]   +  
[info]   +  
[info]   + Please meditate on koan "None equals None" of suite "AboutEmptyValues" 
[info]   +  
[info]   +  
[info]   +  
[info]   + ***************************************** 

...and so you go look at this unit test and it says:

test("None equals None") {
  assert(None === __)
}

...and, after meditation, you realize that you should fill in the blank like this:

test("None equals None") {
  assert(None === None)
}

...and then it moves on to the next unit test.

My question, though, is what is this === operator? I can't seem to find it anywhere. Is this a DSL operator defined in the Scala Koans project itself? Or is it part of the ScalaTest framework? Or in Scala proper?

解决方案

This is the triple-equals operator from ScalaTest. Have a look at this page: Getting Started with FunSuite. It says:

ScalaTest lets you use Scala's assertion syntax, but defines a triple equals operator (===) to give you better error messages. The following code would give you an error indicating only that an assertion failed:

assert(1 == 2)

Using triple equals instead would give you the more informative error message, "1 did not equal 2":

assert(1 === 2)

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