fix: gracefully handle corrupt webhook metadata in pact URL

lib/pact_broker/api/pact_broker_urls.rb

@@ -1,11 +1,13 @@
 require 'erb'
 require 'pact_broker/pacts/metadata'
+require 'pact_broker/logging'
 
 module PactBroker
   module Api
     module PactBrokerUrls
 
       include PactBroker::Pacts::Metadata
+      include PactBroker::Logging
       # TODO make base_url the last and optional argument for all methods, defaulting to ''
 
       extend self
@@ -70,8 +72,13 @@ def encode_webhook_metadata(metadata)
 
       def decode_webhook_metadata(metadata)
         if metadata
-          Rack::Utils.parse_nested_query(Base64.strict_decode64(metadata)).each_with_object({}) do | (k, v), new_hash |
-            new_hash[k.to_sym] = v
+          begin
+            Rack::Utils.parse_nested_query(Base64.strict_decode64(metadata)).each_with_object({}) do | (k, v), new_hash |
+              new_hash[k.to_sym] = v
+            end
+          rescue StandardError => e
+            logger.warn("Exception parsing webhook metadata: #{metadata}", e)
+            {}
           end
         else
           {}

spec/lib/pact_broker/api/pact_broker_urls_spec.rb

@@ -3,6 +3,10 @@
 module PactBroker
   module Api
     describe PactBrokerUrls do
+      before do
+        allow(PactBrokerUrls).to receive(:logger).and_return(logger)
+      end
+      let(:logger) { double('logger').as_null_object }
 
       # Regex find all the URL parameter names
       # \/\{[^\}\s\[\(\.]+\}
@@ -117,6 +121,17 @@ module Api
             expect(PactBrokerUrls.decode_webhook_metadata(nil)).to eq({})
           end
         end
+
+        context "when the metadata is not valid base64" do
+          it "returns an empty hash" do
+            expect(PactBrokerUrls.decode_webhook_metadata("foo==,")).to eq({})
+          end
+
+          it "logs a warning" do
+            expect(logger).to receive(:warn).with("Exception parsing webhook metadata: foo==,", ArgumentError)
+            PactBrokerUrls.decode_webhook_metadata("foo==,")
+          end
+        end
       end
 
       describe "latest_verification_for_pact_url" do