runner shouldn't think that all ruby methods are git commands

closes #64

lib/hub/args.rb

@@ -13,6 +13,7 @@ def initialize(*args)
       @executable = ENV["GIT"] || "git"
       @after = nil
       @skip = false
+      @original_args = args.first
     end
 
     # With no arguments, returns the `after` callback.
@@ -74,5 +75,10 @@ def words
     def flags
       self - words
     end
+
+    # Tests if arguments were modified since instantiation
+    def changed?
+      self != @original_args
+    end
   end
 end

lib/hub/runner.rb

@@ -15,7 +15,7 @@ def initialize(*args)
 
       # git commands can have dashes
       cmd = @args[0].sub(/(\w)-/, '\1_')
-      Commands.send(cmd, @args) if Commands.respond_to?(cmd)
+      Commands.send(cmd, @args) if Commands.method_defined?(cmd)
     end
 
     # Shortcut

test/helper.rb

@@ -70,6 +70,12 @@ def assert_command(input, expected)
     assert_equal expected, Hub(input).command, "$ git #{input}"
   end
 
+  # Asserts that the command will be forwarded to git without changes
+  def assert_forwarded(input)
+    cmd = Hub(input)
+    assert !cmd.args.changed?, "arguments were not supposed to change: #{cmd.args.inspect}"
+  end
+
   # Asserts that `hub` will show a specific alias command for a
   # specific shell.
   #

test/hub_test.rb

@@ -711,6 +711,11 @@ def test_context_method_doesnt_hijack_git_command
     assert_command 'remotes', 'git remotes'
   end
 
+  def test_not_choking_on_ruby_methods
+    assert_forwarded 'id'
+    assert_forwarded 'name'
+  end
+
   def test_multiple_remote_urls
     stub_repo_url("git://example.com/other.git\ngit://github.com/my/repo.git")
     assert_command "browse", "open http://github.com/my/repo"