Separate out handling of Solr timeout errors with it's own exception class

lib/blacklight/exceptions.rb

@@ -16,6 +16,8 @@ class ExpiredSessionToken < StandardError
 
     class ECONNREFUSED < ::Errno::ECONNREFUSED; end
 
+    class RepositoryTimeout < Timeout::Error; end
+
     class IconNotFound < StandardError
     end
   end

lib/blacklight/solr/repository.rb

@@ -77,7 +77,12 @@ def send_and_receive(path, solr_params = {})
         Blacklight.logger&.debug("Solr response: #{solr_response.inspect}") if defined?(::BLACKLIGHT_VERBOSE_LOGGING) && ::BLACKLIGHT_VERBOSE_LOGGING
         solr_response
       end
+    rescue *[(defined?(RSolr::Error::Timeout) ? RSolr::Error::Timeout : nil)].compact => e
+      # RSolr 2.4.0+ has a RSolr::Error::Timeout that we'd like to treat specially instead of
+      # lumping into RSolr::Error::Http
+      raise Blacklight::Exceptions::RepositoryTimeout, "Timeout connecting to Solr instance using #{connection.inspect}: #{e.inspect}"
     rescue Errno::ECONNREFUSED => e
+      # intended for and likely to be a RSolr::Error:ConnectionRefused, specifically.
       raise Blacklight::Exceptions::ECONNREFUSED, "Unable to connect to Solr instance using #{connection.inspect}: #{e.inspect}"
     rescue RSolr::Error::Http => e
       raise Blacklight::Exceptions::InvalidRequest, e.message

spec/services/blacklight/search_service_spec.rb

@@ -384,6 +384,15 @@
     expect { service.repository.search }.to raise_exception(/Unable to connect to Solr instance/)
   end
 
+  it "raises a Blacklight exception if RSolr raises a timeout error connecting to Solr instance" do
+    # rsolr api is mess, let's
+    rsolr_timeout = RSolr::Error::Timeout.new(nil, nil)
+    allow(rsolr_timeout).to receive(:to_s).and_return("mocked RSolr timeout")
+
+    allow(blacklight_solr).to receive(:send_and_receive).and_raise(rsolr_timeout)
+    expect { service.repository.search }.to raise_exception(Blacklight::Exceptions::RepositoryTimeout, /Timeout connecting to Solr instance/)
+  end
+
   describe "#previous_and_next_documents_for_search" do
     let(:user_params) { { q: '', per_page: 100 } }