Support headers passed in using string keys when Vary header is in a different case

lib/faraday/http_cache/strategies/by_url.rb

@@ -99,7 +99,7 @@ def vary_matches?(cached_response, request, cached_request)
           vary = headers['Vary'].to_s
 
           vary.empty? || (vary != '*' && vary.split(/[\s,]+/).all? do |header|
-            request.headers[header] == cached_request[:headers][header]
+            request.headers[header] == (cached_request[:headers][header] || cached_request[:headers][header.downcase])
           end)
         end
 

spec/strategies/by_url_spec.rb

@@ -86,6 +86,24 @@
 
         expect(subject.read(request)).to be_a(Faraday::HttpCache::Response)
       end
+
+      context 'with a Vary header in the response in a different case than the matching request header' do
+        let(:request) do
+          Faraday::HttpCache::Request.new(
+            method: :get,
+            url: 'http://test/index',
+            headers: Faraday::Utils::Headers.new({ 'accept' => 'application/json' })
+          )
+        end
+        let(:response) do
+          Faraday::HttpCache::Response.new(response_headers: Faraday::Utils::Headers.new({ vary: 'Accept' }))
+        end
+
+        it 'reads stored message' do
+          subject.write(request, response)
+          expect(subject.read(request)).to be_a(Faraday::HttpCache::Response)
+        end
+      end
     end
 
     context 'with the JSON serializer' do