Ruby 我可以别名RSpec匹配器吗？

我有两个匹配者，除了他们的名字外，他们是一样的：

RSpec::Matchers.define :be_the_downcased_version_of do |actual|
    match do |actual|
        @actual = actual
        @expected = expected

        @actual == @expected.downcase
    end

    failure_message do |actual|
        "Expected #{@actual.inspect} to be the downcased version of #{expected.inspect}.\nIt was not: #{@actual.inspect}"
    end

    failure_message_when_negated do |actual|
        "Expected #{@actual.inspect} to not be the downcased version of #{expected.inspect}.\nIt was: #{@actual.inspect}"
    end

    description do
        "be the downcased version of #{expected.inspect}"
    end
end

RSpec::Matchers.define :return_the_downcased_version_of do |actual|
    match do |actual|
        @actual = actual
        @expected = expected

        @actual == @expected.downcase
    end

    failure_message do |actual|
        "Expected #{@actual.inspect} to be the downcased version of #{expected.inspect}.\nIt was not: #{@actual.inspect}"
    end

    failure_message_when_negated do |actual|
        "Expected #{@actual.inspect} to not be the downcased version of #{expected.inspect}.\nIt was: #{@actual.inspect}"
    end

    description do
        "be the downcased version of #{expected.inspect}"
    end
end

我可以像在用Ruby给方法加别名时那样给它们加别名吗

alias_method :foo_meth, :bar_meth

---

是的，您可以为使用RSpec的matcher DSL定义的matcher设置别名。我所知道的最方便的方法是在块之前的

中重新打开示例上下文的类，并在那里别名该方法

但首先，让我们清理一下你的媒人

传递给
匹配器的块。define
采用预期值，而不是
实际值，作为其参数
您不需要这些实例变量；它们的值已在块参数中可用
在spec/support/be_.rb的\u downcased \u版本中：

RSpec::Matchers.define :be_the_downcased_version_of do |expected|
  match do |actual|
    actual == expected.downcase
  end

  failure_message_for_should do |actual|
    "Expected #{actual.inspect} to be the downcased version of #{expected.inspect}.\nIt was not: #{actual.inspect}"
  end

  failure_message_for_should_not do |actual|
    "Expected #{actual.inspect} to not be the downcased version of #{expected.inspect}.\nIt was: #{actual.inspect}"
  end

  description do
    "be the downcased version of #{expected.inspect}"
  end

end

alias_method :return_the_downcased_version_of, :be_the_downcased_version_of

def be_the_downcased_version_of(actual)
  BeTheDowncasedVersionOf.new actual
end

class BeTheDowncasedVersionOf
  def initialize(expected)
    @expected = expected
  end

  def matches?(actual)
    @actual = actual
    @actual == @expected.downcase
  end

  def failure_message_for_should
    "Expected #{@actual.inspect} to be the downcased version of #{@expected.inspect}.\nIt was not: #{@actual.inspect}"
  end

  def failure_message_for_should_not
    "Expected #{@actual.inspect} to not be the downcased version of #{@expected.inspect}.\nIt was: #{@actual.inspect}"
  end

  def description
    "be the downcased version of #{@expected.inspect}"
  end

end

要在spec/spec_helper.rb中别名该匹配器定义的方法，请执行以下操作：

config.before :each do
  class << self
    alias_method :return_the_downcased_version_of, :be_the_downcased_version_of
  end
end

正如CB利亚德所评论的，你可以简单地做到

RSpec::Matchers.define :be_the_downcased_version_of do |expected|
  match do |actual|
    # ...
  end
  # ...
end

RSpec::Matchers.alias_matcher :return_the_downcased_version_of, :be_the_downcased_version_of

化名为匹配者。在我看来，这是一种非常干净的解决方案。
另一种替代方法是使用。然后可以编写
RSpec:：Matchers.alias\u matcher:return\u downcased\u version\u of，：be\u downcased\u version\u of
。