Ruby recursive method needs return clause - ruby

Question

I could be missing the obvious here, but this code is failing unless I use the return clause when call it recursively on Net::HTTPRedirection case.
def fetch_headers(limit = REDIRECT_LIMIT)
# You should choose a better exception.
raise ArgumentError, 'too many HTTP redirects' if limit == 0
http = Net::HTTP.new(#uri.host, #uri.port)
http.use_ssl = true if #uri.scheme == 'https'
request_uri = #uri.request_uri.nil? ? '/' : #uri.request_uri
http.request_head(request_uri) do |response|
case response
when Net::HTTPSuccess then
return response
when Net::HTTPRedirection then
location = response['location']
parsed_location = URI.parse location
#uri = parsed_location.absolute? ? parsed_location : #uri.merge(parsed_location)
fetch_headers(limit - 1)
else
return response.value
end
end
end
The caller method:
def perform(link_id)
link = Link.find(link_id)
url = link.url =~ /^http/ ? link.url : "http://#{link.url}"
#uri = URI.parse url
headers = fetch_headers
case headers.content_type
when /application/
filename = File.basename(#uri.path)
link.update title: filename
when /html/
response = fetch_page
page = Nokogiri::HTML(response)
link.update title: page_title(page), description: page_description(page)
else
logger.warn "URL #{url} with unknow mime-type: #{headers.content_type}"
end
end
Here is the spec I am running:
it 'follows the redirects using relative URL' do
link = create(:link, url: url)
path = '/welcome.html'
stub_request(:head, url).to_return(status: 302, body: '',
headers: { 'Location' => path })
redirect_url = "#{url}#{path}"
stub_request(:head, redirect_url).to_return(status: 200, body: '',
headers: html_header)
stub_request(:get, redirect_url).to_return(status: 200, body: title_html_raw,
headers: html_header)
UrlScrapperJob.perform_now link.id
link.reload
expect(link.title).to match(/page title/)
end
Here are the result of fetch_headers method:
With the return clause: #<Net::HTTPOK 200 readbody=true>
Without the return clause: #<Net::HTTPFound 302 readbody=true>
The result I would expect would be the HTTPOK 200 because it should follow the redirects until a 200 OK.

Answer 1

The difference is the value, returned from fetch_headers function.
return returns it’s argument as a result of a function call.
Without explicit return, the return value is what http.request_head(request_uri, &block) returns, which is apparently causes the infinite recursion.
You might want to try
http.request_head(request_uri) do |response|
case response
when Net::HTTPSuccess then
response
when Net::HTTPRedirection then
location = response['location']
parsed_location = URI.parse location
#uri = parsed_location.absolute? ? parsed_location : #uri.merge(parsed_location)
fetch_headers(limit - 1)
else
response.value
end
end.tap { |result| puts result } # ⇐ here
to examine what is actual result without explicit return.