Add test related to a bug of network graph.

features/project/network.feature

@@ -11,14 +11,16 @@ Feature: Project Network Graph
     And page should have "master" on graph
 
   @javascript
-  Scenario: I should switch ref to "stable"
+  Scenario: I should switch "branch" and "tag"
     When I switch ref to "stable"
-    Then page should have network graph
-    And page should select "stable" in select box
+    Then page should select "stable" in select box
     And page should have "stable" on graph
+    When I switch ref to "v2.1.0"
+    Then page should select "v2.1.0" in select box
+    And page should have "v2.1.0" on graph
 
   @javascript
-  Scenario: I should looking for a commit by SHA of "v2.1.0"
+  Scenario: I should looking for a commit by SHA
     When I looking for a commit by SHA of "v2.1.0"
     Then page should have network graph
     And page should select "master" in select box

features/steps/project/project_network_graph.rb

@@ -30,10 +30,19 @@ class ProjectNetworkGraph < Spinach::FeatureSteps
     sleep 2
   end
 
+  When 'I switch ref to "v2.1.0"' do
+    page.select 'v2.1.0', :from => 'ref'
+    sleep 2
+  end
+
   And 'page should select "stable" in select box' do
     page.should have_selector '#ref_chzn span', :text => "stable"
   end
 
+  And 'page should select "v2.1.0" in select box' do
+    page.should have_selector '#ref_chzn span', :text => "v2.1.0"
+  end
+
   And 'page should have "stable" on graph' do
     within '.graph' do
       page.should have_content 'stable'