Fixed response stubbing credentials.

The `Aws::DefaultCredentialChain` is no longer used when
setting `stub_responses: true`.

Fixes #835

CHANGELOG.md

@@ -1,6 +1,13 @@
 Unreleased Changes
 ------------------
 
+* Issue - Response Stubbing - When enabling response stubbing via
+  `stub_responses: true` on a client, the default credential chain is longer
+  used to source credentials. Instead a set of fake stubbed static credentials
+  are used by default.
+
+  See [related GitHub issue #835](https://github.com/aws/aws-sdk-ruby/pull/835)
+
 2.0.48 (2015-06-04)
 ------------------
 

aws-sdk-core/lib/aws-sdk-core/client.rb

@@ -12,6 +12,7 @@ class Client < Seahorse::Client::Base
       'Aws::Plugins::GlobalConfiguration',
       'Aws::Plugins::RegionalEndpoint',
       'Aws::Plugins::RequestSigner',
+      'Aws::Plugins::StubResponses',
     ]
 
     include ClientPaging

aws-sdk-core/lib/aws-sdk-core/client_stubs.rb

@@ -8,11 +8,6 @@ module Aws
   # behavior.
   module ClientStubs
 
-    # @api private
-    def self.included(subclass)
-      subclass.add_plugin('Aws::Plugins::StubResponses')
-    end
-
     def initialize(*args)
       @stubs = {}
       @stub_mutex = Mutex.new

aws-sdk-core/spec/aws/client_spec.rb

@@ -10,7 +10,15 @@ module Aws
       secret_access_key: 'secret',
     }}
 
-    describe '#stub' do
+    describe 'response stubbing' do
+
+      it 'skips the credential provider chain' do
+        expect(Aws::CredentialProviderChain).not_to receive(:new)
+        creds = S3::Client.new(stub_responses:true).config.credentials
+        expect(creds).to be_kind_of(Credentials)
+        expect(creds.access_key_id).to eq('stubbed-akid')
+        expect(creds.secret_access_key).to eq('stubbed-secret')
+      end
 
       it 'raises an error if stubbed_responses is not enabled' do
         client = S3::Client.new(options.merge(stub_responses: false))