Add test for --ff merge

features/merge.feature

@@ -83,6 +83,32 @@ Feature: hub merge
       Fast-forward (no commit created; -m option ignored)
       """
 
+  Scenario: Merge pull request with --ff option
+    Given the GitHub API server:
+      """
+      require 'json'
+      get('/repos/defunkt/hub/pulls/164') { json \
+        :head => {
+          :ref => "hub_merge",
+          :repo => {
+            :owner => { :login => "jfirebaugh" },
+            :name => "hub",
+            :private => false
+          }
+        },
+        :title => "Add `hub merge` command"
+      }
+      """
+    And there is a commit named "jfirebaugh/hub_merge"
+    When I successfully run `hub merge --ff https://github.com/defunkt/hub/pull/164`
+    Then "git fetch git://github.com/jfirebaugh/hub.git +refs/heads/hub_merge:refs/remotes/jfirebaugh/hub_merge" should be run
+    And "git merge --ff jfirebaugh/hub_merge -m Merge pull request #164 from jfirebaugh/hub_merge" should be run
+    When I successfully run `git show -s --format=%B`
+    Then the output should contain:
+      """
+      Fast-forward (no commit created; -m option ignored)
+      """
+
   Scenario: Merge private pull request
     Given the GitHub API server:
       """