Fix bug: default credential provider hides sub credential provider's fetching

xli · xli · commit 42fbe7e91776 · 2013-01-30T12:25:42.000-08:00
credentials error.

The default credential provider will try to rescue sub provider's
MissingCredentialsError for looking up the right credential provider.
However, the way using 'rescue' keyword is not correct, and it
actually rescued all the StandardError raised from sub provider's
credentials method.
diff --git a/lib/aws/core/credential_providers.rb b/lib/aws/core/credential_providers.rb
@@ -116,7 +116,10 @@ def initialize static_credentials = {}
 
         def credentials
           providers.each do |provider|
-            return provider.credentials rescue Errors::MissingCredentialsError
+            begin
+              return provider.credentials
+            rescue Errors::MissingCredentialsError
+            end
           end
           raise Errors::MissingCredentialsError
         end
diff --git a/spec/aws/core/credential_providers_spec.rb b/spec/aws/core/credential_providers_spec.rb
@@ -97,6 +97,17 @@ module CredentialProviders
             :session_token => 'token-2'
           }
         end
+
+        it 'should not hide real error of fetching credentials' do
+          dp = DefaultProvider.new
+          ec2_provider = dp.providers[0] = EC2Provider.new
+          ec2_provider.stub(:credentials) do
+            raise "Something wrong"
+          end
+          lambda {
+            dp.credentials
+          }.should raise_error('Something wrong')
+        end
       end
 
       describe StaticProvider do
