Don't always append global/default headers

Invokations of `global` or `default` methods with bare blocks (that is,
without option declarations) appends to the `helps` local variable
unwanted information, which results in this:

  % my_cli_app --help
    Global options

    Other options
  %

Fix it by checking whether global or default options, actually, have any
options defined.

Signed-off-by: Kyrylo Silin <kyrylosilin@gmail.com>

1 files changed, 14 insertions, 0 deletions

diff --git a/test/commands_test.rb b/test/commands_test.rb
index 174dcf2..6721400 100644
--- a/test/commands_test.rb
+++ b/test/commands_test.rb
@@ -13,6 +13,16 @@ class CommandsTest < TestCase
         add_callback(:empty) { 'version 1' }
       end
     end
+
+    @empty_commands = Slop::Commands.new do
+      default do
+      end
+
+      global do
+      end
+
+      on 'verbose'
+    end
   end
 
   test "it nests instances of Slop" do
@@ -75,6 +85,10 @@ class CommandsTest < TestCase
     assert_kind_of Slop, @commands.global
   end
 
+  test "empty default/global blocks don't add their titles in the help output" do
+    assert_empty @empty_commands.to_s
+  end
+
   test "parse does nothing when there's nothing to parse" do
     assert @commands.parse []
   end