ScalaTest 如何在混合多个匹配器时排除 MustMatchers

Question

使用 Scalatest 2.2.5、Scala 2.11.8、sbt 0.13.13、JDK 1.8.121

我们的代码库不断发展，开发人员对测试风格和匹配器有不同的偏好。在下面的代码中，测试使用 Matchers，它还需要在其声明中混入一个 trait OurCommonTestHelpers，如果自己混入 MustMatchers。很容易解决，把with Matchers去掉，把should equal换成must equal就可以了。假设我更喜欢动词 should，只是因为它用在 ScalaTest User Guide

中

我们可能有一天会标准化。但是现在，是否可以在发生冲突时排除匹配器？

import org.scalatest.{FreeSpec, Matchers}

class MyBizLogicTest extends FreeSpec 
with Matchers // <-- conflict with MustMatchers from trait OurCommonTestHelpers  
with OurCommonTestHelpers 
{
  "A trivial addition" in {
      (1 + 2) should equal (3)
  }
}

trait OurCommonTestHelpers extends MockitoSugar with MustMatchers {
  ???
}

代码编译失败：

Error:(26, 7) class MyBizLogicTest inherits conflicting members:
  method convertSymbolToHavePropertyMatcherGenerator in trait Matchers of type (symbol: Symbol)MyBizLogicTest.this.HavePropertyMatcherGenerator  and
  method convertSymbolToHavePropertyMatcherGenerator in trait MustMatchers of type (symbol: Symbol)MyBizLogicTest.this.HavePropertyMatcherGenerator
(Note: this can be resolved by declaring an override in class MyBizLogicTest.);
 other members with override errors are: equal, key, value, a, an, theSameInstanceAs, regex, <, >, <=, >=, definedAt, evaluating, produce, oneOf, atLeastOneOf, noneOf, theSameElementsAs, theSameElementsInOrderAs, only, inOrderOnly, allOf, inOrder, atMostOneOf, thrownBy, message, all, atLeast, every, exactly, no, between, atMost, the, convertToRegexWrapper, of
class MyBizLogicTest extends FreeSpec

注意：我试图通过 import org.scalatest.{MustMatchers => _} 排除 MustMatchers，但这对编译错误没有影响。

Answer 1

我认为你做不到，因为 class 都没有继承另一个。显而易见的方法是添加一个额外的类型：

// name just to be clear, I don't suggest actually using this one
trait OurCommonTestHelpersWithoutMatchers extends ... {
  // everything in OurCommonTestHelpers which doesn't depend on MustMatchers
}

trait OurCommonTestHelpers extends OurCommonTestHelpersWithoutMatchers with MustMatchers {
  ...
}

class MyBizLogicTest extends FreeSpec 
with Matchers 
with OurCommonTestHelpersWithoutMatchers 
{
  "A trivial addition" in {
      (1 + 2) should equal (3)
  }
}

NOTE: I have tried to exclude the MustMatchers by import org.scalatest.{MustMatchers => _} but this has no effect on the compile error.

您不能通过不导入来删除继承的 成员。如果您通过在 OurCommonTestHelpers 中导入来访问它们，您根本不会在 MyBizLogicTest 中导入它们（但需要在您需要它们的其他 class 中导入）。

ScalaTest 如何在混合多个匹配器时排除 MustMatchers

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