Add Cursor spec

lib/twitter/cursor.rb

@@ -14,7 +14,7 @@ def initialize(cursor, method, klass=nil)
         else
           item
         end
-      end
+      end unless cursor[method.to_s].nil?
       @next_cursor = cursor['next_cursor']
       @previous_cursor = cursor['previous_cursor']
       singleton_class.class_eval do

spec/twitter/cursor_spec.rb

@@ -0,0 +1,43 @@
+require 'helper'
+
+describe Twitter::Cursor do
+
+  describe "#first?" do
+    context "when previous cursor equals zero" do
+      before do
+        @cursor = Twitter::Cursor.new({'previous_cursor' => 0}, 'ids')
+      end
+      it "should return true" do
+        @cursor.first?.should be_true
+      end
+    end
+    context "when previous cursor does not equal zero" do
+      before do
+        @cursor = Twitter::Cursor.new({'previous_cursor' => 1}, 'ids')
+      end
+      it "should return true" do
+        @cursor.first?.should be_false
+      end
+    end
+  end
+
+  describe "#last?" do
+    context "when next cursor equals zero" do
+      before do
+        @cursor = Twitter::Cursor.new({'next_cursor' => 0}, 'ids')
+      end
+      it "should return true" do
+        @cursor.last?.should be_true
+      end
+    end
+    context "when next cursor does not equal zero" do
+      before do
+        @cursor = Twitter::Cursor.new({'next_cursor' => 1}, 'ids')
+      end
+      it "should return false" do
+        @cursor.last?.should be_false
+      end
+    end
+  end
+
+end