diff --git a/lib/egnyte.rb b/lib/egnyte.rb
index 6adddb7..2c52bee 100644
--- a/lib/egnyte.rb
+++ b/lib/egnyte.rb
@@ -16,4 +16,6 @@
 require "egnyte/file"
 
 module Egnyte
+  class DomainRequired < StandardError; end
+  class UnsupportedAuthStrategy < StandardError; end
 end
diff --git a/spec/session_spec.rb b/spec/session_spec.rb
new file mode 100644
index 0000000..aa8b9c2
--- /dev/null
+++ b/spec/session_spec.rb
@@ -0,0 +1,9 @@
+require 'spec_helper'
+
+describe Egnyte::Session do
+  it 'raises DomainRequired error if domain is not given' do
+    expect do
+      Egnyte::Session.new(key: 'xxxxxxx')
+    end.to raise_error Egnyte::DomainRequired
+  end
+end