diff --git a/lib/google/api_client/auth/storage.rb b/lib/google/api_client/auth/storage.rb
index db308e5e6..5197cf2d7 100644
--- a/lib/google/api_client/auth/storage.rb
+++ b/lib/google/api_client/auth/storage.rb
@@ -48,7 +48,7 @@ module Google
       #    already associated with this instance will be written.
       def write_credentials(authorization=nil)
         @authorization = authorization if authorization
-        if @authorization.refresh_token
+        if @authorization.respond_to?(:refresh_token) && @authorization.refresh_token
           store.write_credentials(credentials_hash)
         end
       end
diff --git a/spec/google/api_client/auth/storage_spec.rb b/spec/google/api_client/auth/storage_spec.rb
index b61057df3..1c319f4b7 100644
--- a/spec/google/api_client/auth/storage_spec.rb
+++ b/spec/google/api_client/auth/storage_spec.rb
@@ -40,8 +40,8 @@ describe Google::APIClient::Storage do
         subject.should_receive(:refresh_authorization)
         subject.authorize
       end
-
     end
+
     describe 'without credentials' do
 
       it 'should return false' do
@@ -51,19 +51,34 @@ describe Google::APIClient::Storage do
     end
   end
 
-
   describe 'write_credentials' do
+    it 'should call store to write credentials' do
+      authorization_stub = double
+      authorization_stub.should_receive(:refresh_token).and_return(true)
+      subject.should_receive(:credentials_hash)
+      subject.store.should_receive(:write_credentials)
+      subject.write_credentials(authorization_stub)
+      subject.authorization.should == authorization_stub
+    end
 
-    it 'should store credentials to var'
-
-    it 'should call store to write credentials'
-
-    it 'should not call store to write credentials'
+    it 'should not call store to write credentials' do
+      subject.should_not_receive(:credentials_hash)
+      subject.store.should_not_receive(:write_credentials)
+      expect {
+        subject.write_credentials()
+      }.not_to raise_error
+    end
+    it 'should not call store to write credentials' do
+      subject.should_not_receive(:credentials_hash)
+      subject.store.should_not_receive(:write_credentials)
+      expect {
+        subject.write_credentials('something')
+      }.not_to raise_error
+    end
 
   end
 
   describe 'refresh_authorization' do
-
     it 'should call refresh and write credentials' do
       subject.should_receive(:write_credentials)
       authorization_stub = double
@@ -74,8 +89,31 @@ describe Google::APIClient::Storage do
   end
 
   describe 'load_credentials' do
-    it 'should call store to load credentials'
-
+    it 'should call store to load credentials' do
+      subject.store.should_receive(:load_credentials)
+      subject.send(:load_credentials)
+    end
   end
 
+  describe 'credentials_hash' do
+    it 'should return an hash' do
+      authorization_stub = double
+      authorization_stub.should_receive(:access_token)
+      authorization_stub.should_receive(:client_id)
+      authorization_stub.should_receive(:client_secret)
+      authorization_stub.should_receive(:expires_in)
+      authorization_stub.should_receive(:refresh_token)
+      authorization_stub.should_receive(:issued_at).and_return('100')
+      subject.stub(:authorization).and_return(authorization_stub)
+      credentials = subject.send(:credentials_hash)
+      credentials.should include(:access_token)
+      credentials.should include(:authorization_uri)
+      credentials.should include(:client_id)
+      credentials.should include(:client_secret)
+      credentials.should include(:expires_in)
+      credentials.should include(:refresh_token)
+      credentials.should include(:token_credential_uri)
+      credentials.should include(:issued_at)
+    end
+  end
 end