Custom matcher to verify content type of a request

have_content_type_matcher.rb

RSpec::Matchers.define :have_content_type do |content_type|

  MIME_TYPES = { json: 'application/json' }

  match do |response|
    response_content_type = response.header['Content-Type']
    response_content_type.split(";").include?(MIME_TYPES[content_type])
  end

  description do
    "has #{action} as content type"
  end

  failure_message do |response|
    "response does not have #{content_type} as Content-Type"
  end

  failure_message_when_negated do |response|
    "response has #{content_type} as Content-Type"
  end

end