ruby - RSpec 自定义可区分匹配器

Question

我在 RSpec 中有一个自定义匹配器，它忽略空格/换行符，只匹配内容:

RSpec::Matchers.define :be_matching_content do |expected|
  match do |actual|
    actual.gsub(/\s/,'').should == expected.gsub(/\s/,'')
  end

  diffable
end

我可以这样使用它:

    body = "   some data   \n more data"
    body.should be_matching_content("some data\nmore wrong data")

但是，当测试失败时(如上面的测试)，diff 输出看起来不太好:

   -some data
   -more wrong data
   +   some data   
   + more data

是否可以配置可微分输出？第一行some data是对的，但是第二行more wrong data是错的。仅将第二行作为失败的根本原因将非常有用。

Answer 1

我认为您应该禁用 RSpec 中的默认 diffable 行为并替换为您自己的实现:

RSpec::Matchers.define :be_matching_content do |expected|
  match do |actual|
    @stripped_actual = actual.gsub(/\s/,'')
    @stripped_expected = expected.gsub(/\s/,'')
    expect(@stripped_actual).to eq @stripped_expected
  end

  failure_message do |actual|
    message = "expected that #{@stripped_actual} would match #{@stripped_expected}"
    message += "\nDiff:" + differ.diff_as_string(@stripped_actual, @stripped_expected)
    message
  end

  def differ
    RSpec::Support::Differ.new(
        :object_preparer => lambda { |object| RSpec::Matchers::Composable.surface_descriptions_in(object) },
        :color => RSpec::Matchers.configuration.color?
    )
  end
end

RSpec.describe 'something'do
  it 'should diff correctly' do
    body = "   some data   \n more data"
    expect(body).to be_matching_content("some data\nmore wrong data")
  end
end

产生以下内容:

Failures:

  1) something should diff correctly
     Failure/Error: expect(body).to be_matching_content("some data\nmore wrong data")
       expected that somedatamoredata would match somedatamorewrongdata
       Diff:
       @@ -1,2 +1,2 @@
       -somedatamorewrongdata
       +somedatamoredata

如果需要，您可以使用自定义 differ，甚至可以将整个匹配器重新实现为对 diff 命令的系统调用，如下所示:

♥ diff -uw --label expected --label actual <(echo "   some data    \n more data") <(echo "some data\nmore wrong data")
--- expected
+++ actual
@@ -1,2 +1,2 @@
    some data    
- more data
+more wrong data

干杯!