Just show blank option if neither include blank and prompt are sent a…

…s options, resolving issue formtastic#16.

lib/formtastic.rb

@@ -554,10 +554,14 @@ def hidden_input(method, options)
     #
     # By default, all select inputs will have a blank option at the top of the list. You can add
     # a prompt with the :prompt option, or disable the blank option with :include_blank => false.
+    #
     def select_input(method, options)
       collection = find_collection_for_column(method, options)
       html_options = options.delete(:input_html) || {}
-      options[:include_blank] ||= true
+
+      unless options.key?(:include_blank) || options.key?(:prompt)
+        options[:include_blank] = true
+      end
 
       reflection = find_reflection(method)
       if reflection && [ :has_many, :has_and_belongs_to_many ].include?(reflection.macro)

spec/formtastic_spec.rb

@@ -1511,7 +1511,7 @@ def custom(arg1, arg2, options = {})
           end
 
           it 'should have a blank option by default' do
-            output_buffer.should have_tag("form li select option[@value='']", //)
+            output_buffer.should have_tag("form li select option[@value='']", "")
           end
         end
 
@@ -1524,25 +1524,25 @@ def custom(arg1, arg2, options = {})
           end
 
           it 'should not have a blank option' do
-            output_buffer.should have_tag("form li select option[@value='']", //)
+            output_buffer.should_not have_tag("form li select option[@value='']", "")
           end
         end
-        
-        describe 'when :include_blank => true and :prompt => "choose something" is set' do
+
+        describe 'when :prompt => "choose something" is set' do
           before do
             @new_post.stub!(:author_id).and_return(nil)
             semantic_form_for(@new_post) do |builder|
-              concat(builder.input(:author, :as => :select, :include_blank => true, :prompt => "choose author"))
+              concat(builder.input(:author, :as => :select, :prompt => "choose author"))
             end
           end
 
-          it 'should have a blank select option' do
-            output_buffer.should have_tag("form li select option[@value='']", //)
-          end
-
           it 'should have a select with prompt' do
             output_buffer.should have_tag("form li select option[@value='']", /choose author/)
           end
+
+          it 'should not have a blank select option' do
+            output_buffer.should_not have_tag("form li select option[@value='']", "")
+          end
         end
 
         describe 'when no object is given' do