have_same_attributes : RSpec用Custom Machter。ActiveRecord/ActiverResrouce/Hashなどをゆるふわくmatchさせる

have_same_attributes.rb

# Rspec用のCustom Matcher
# 
# attributesメソッドを持つオブジェクト同士やHashを再帰的にmatchさせる
#
# ActiveRecord/ActiveModel/ActiveResrouce/Hashなどをゆるふわく
# 一致するか調べる。例えば、StringとSymbolは区別しないし、[]や{}やnilは同一視する。
#
#   it { should have_same_attributes(hash) }
#   it { should have_same_attributes(:foo => 1,:bar => 2) }
#
# exceptを付けると、除外するkeyを指定できる
# 
#   it { should have_same_attributes(hash).except(:hoge,:fuga) }
# 
# onlyを付けると、指定したkeyのみで比較する
# 
#   it { should have_same_attributes(hash).only(:hoge,:fuga) }
# 
# strictlyを付けると、ゆるふわ比較を止める
# 
#   it { should have_same_attributes(hash).strictly }
# 
RSpec::Matchers.define :have_same_attributes do |expected|

  @only = []
  @ignored = [:id,  :updated_at,  :created_at, :versions]
  @appended_ignored = []

  chain :except do |*attr_names|
    case attr_names
      when Array then @ignored += attr_names.flatten
      else @ignored << attr_names
    end
    @appended_ignored = attr_names.flatten
  end

  chain :only do |*attr_names|
    case attr_names
      when Array then @only += attr_names.flatten
      else @only << attr_names
    end
  end

  @strict = false
  chain :sttictly do |flag|
    @strict = flag.nil? ? true : flag
  end

  def has_attributes?(obj)
    case obj
      when Hash then true
      else obj.nil? ? false : obj.respond_to?(:attributes)
    end
  end

  def to_attributes(obj)
    raise "expected hash or object but nil." if obj.nil?
    hash = case obj
      when Hash then obj
      else
        raise "undefined method 'attributes'" unless obj.respond_to?(:attributes)
        obj.attributes
    end
    hash = hash.dup.symbolize_keys
    hash.except!(*@ignored) if @ignored.present?
    hash.slice!(*@only)     if @only.present?
    hash
  end

  def compare_value(this, that)
    eq_proc = Proc.new{|a,b| a == b ? nil : "#{a.inspect} != #{b.inspect}" }

    unless @strict
      return nil if this.blank? && that.blank?
    end

    case value_type_of(this)
      when :hash   then compare_attributes(this, that)
      when :array  then compare_array(this, that)
      when :string then
        case value_type_of(that)
          when :string then eq_proc.call(this.to_s, that.to_s)
          else  eq_proc.call(this, that)
        end
      else eq_proc.call(this, that)
    end
  rescue => e
    e
  end

  def value_type_of(obj)
    if obj.instance_of?(Array)
      :array
    elsif has_attributes?(obj)
      :hash
    elsif obj.instance_of?(String) || obj.instance_of?(Symbol)
      :string
    else
      :object
    end
  end

  def compare_array(this, that)
    unless @strict
      return nil if this.blank? && that.blank?
    end

    if value_type_of(that) == :array
      if this.size != that.size
        raise "is Array has different elements #{this.size} to #{that.size}"
      end
      this.zip(that).map {|a, b| compare_value(a, b) }.reject(&:blank?)
    else
      raise "excpected Array but #{that.class}"
    end
  end

  def compare_attributes(this, that)
    errors = {}

    this_attrs = to_attributes(this)
    that_attrs = to_attributes(that)

    if @strict && this_attrs.keys =! that_attrs.keys
      raise "has different keys"
    end

    this_attrs.each do |name, value|
      that_value = that.respond_to?(name) ? that.send(name) : that_attrs[name]
      res = compare_value(value, that_value)
      errors[name] = res if res.present?
    end
    errors
  rescue => e
    e
  end

  match do |actual|
    @errors = compare_attributes(actual, expected)
    @errors.blank?
  end

  description do |args|
    s = "have #{@strict ? 'strictly ' : '' }same attributes as #{expected.inspect}"
    s += " except #{@appended_ignored.inspect}" if @appended_ignored.present?
    s += " only #{@only.inspect}" if @only.present?
    s += "."
  end

  failure_message_for_should do |args|
    "have #{@strict ? 'strictly ' : '' }same attributes as #{expected.inspect}, but #{@errors.pretty_inspect}"

  end

  failure_message_for_should_not do |args|
    "expected have different attributesas #{expected.inspect}"
  end

end