Add unit tests for SoftLayer::Service#user_agent_header.

Author: cphrmky

spec/Service_spec.rb

@@ -286,6 +286,19 @@
   end
 end
 
+describe SoftLayer::Service, "#user_agent_header" do
+  it "should return a default value if not set" do
+    service = SoftLayer::Service.new("SoftLayer_Account", :username => "sample_username", :api_key => "blah")
+    service.user_agent_header.should_not be_empty
+  end
+
+  it "should persist a set value after being set" do
+    service = SoftLayer::Service.new("SoftLayer_Account", :username => "sample_username", :api_key => "blah")
+    service.user_agent_header("foobar").should === {"User-Agent"=>"foobar"}
+    service.user_agent_header.should === {"User-Agent"=>"foobar"}
+  end
+end
+
 describe SoftLayer::Service, "#result_limit" do
   it "should return an APIParameterFilter with itself as the target" do
     service = SoftLayer::Service.new("SoftLayer_Account", :username => "sample_username", :api_key => "blah")