Merge pull request #149 from sonjapeterson/cache-handler-callback

Add optional after_cache_handles_request callback for manipulating cached responses

README.md

@@ -284,6 +284,25 @@ server is required to access the internet.  Most common in larger companies.
 
 `c.cache_request_body_methods` is used to specify HTTP methods of requests that you would like to cache separately based on the contents of the request body. The default is ['post'].
 
+`c.after_cache_handles_request` is used to configure a callback that can operate on the response after it has been retrieved from the cache but before it is returned. The callback receives the request and response as arguments, with a request object like: `{ method: method, url: url, headers: headers, body: body }`. An example usage would be manipulating the Access-Control-Allow-Origin header so that your test server doesn't always have to run on the same port in order to accept cached responses to CORS requests:
+
+```
+Billy.configure do |c|
+  ...
+  fix_cors_header = proc do |_request, response|
+    allowed_origins = response[:headers]['Access-Control-Allow-Origin']
+    if allowed_origins.present?
+      localhost_port_pattern = %r{(?<=http://127\.0\.0\.1:)(\d+)}
+      allowed_origins.sub!(
+        localhost_port_pattern, Capybara.current_session.server.port.to_s
+      )
+    end
+  end
+  c.after_cache_handles_request = fix_cors_header
+  ...
+end
+```
+
 ### Cache Scopes
 
 If you need to cache different responses to the same HTTP request, you can use

lib/billy/config.rb

@@ -10,7 +10,7 @@ class Config
                   :persist_cache, :ignore_cache_port, :non_successful_cache_disabled, :non_successful_error_level,
                   :non_whitelisted_requests_disabled, :cache_path, :proxy_host, :proxy_port, :proxied_request_inactivity_timeout,
                   :proxied_request_connect_timeout, :dynamic_jsonp, :dynamic_jsonp_keys, :merge_cached_responses_whitelist,
-                  :strip_query_params, :proxied_request_host, :proxied_request_port, :cache_request_body_methods
+                  :strip_query_params, :proxied_request_host, :proxied_request_port, :cache_request_body_methods, :after_cache_handles_request
 
     def initialize
       @logger = defined?(Rails) ? Rails.logger : Logger.new(STDOUT)
@@ -40,6 +40,7 @@ def reset
       @proxied_request_host = nil
       @proxied_request_port = 80
       @cache_request_body_methods = ['post']
+      @after_cache_handles_request = nil
     end
   end
 

lib/billy/handlers/cache_handler.rb

@@ -25,6 +25,11 @@ def handle_request(method, url, headers, body)
             replace_response_callback(response, url)
           end
 
+          if Billy.config.after_cache_handles_request
+            request = { method: method, url: url, headers: headers, body: body }
+            Billy.config.after_cache_handles_request.call(request, response)
+          end
+
           return response
         end
       end

spec/lib/billy/handlers/cache_handler_spec.rb

@@ -97,6 +97,23 @@
                                       other_request[:headers],
                                       other_request[:body])).to eql(status: 200, headers: { 'Connection' => 'close' }, content: 'no jsonp but has parentheses()')
       end
+
+      context 'when after_cache_handles_request is set' do
+        it "should call the callback with the request and response" do
+          allow(Billy.config).to receive(:after_cache_handles_request) do
+            proc do |request, response|
+              response[:headers]['Access-Control-Allow-Origin'] = "*"
+              response[:content] = request[:body]
+            end
+          end
+          expect(Billy::Cache.instance).to receive(:cached?).and_return(true)
+          expect(Billy::Cache.instance).to receive(:fetch).and_return(status: 200, headers: { 'Connection' => 'close' }, content: 'The response body')
+          expect(handler.handle_request(request[:method],
+                                        request[:url],
+                                        request[:headers],
+                                        request[:body])).to eql(status: 200, headers: { 'Connection' => 'close', 'Access-Control-Allow-Origin' => "*" }, content: 'Some body')
+        end
+      end
     end
 
     context 'updating jsonp callback names disabled' do