Explicitly set falsy values for :template should not render a template

lib/sinatra/base.rb

@@ -580,7 +580,7 @@ module Sinatra
   #
   # Possible options are:
   #   :content_type   The content type to use, same arguments as content_type.
-  #   :layout         If set to false, no layout is rendered, otherwise
+  #   :layout         If set to something falsy, no layout is rendered, otherwise
   #                   the specified layout is used (Ignored for `sass` and `less`)
   #   :layout_engine  Engine to use for rendering the layout.
   #   :locals         A hash with local variables that should be available
@@ -714,13 +714,15 @@ module Sinatra
       # extract generic options
       locals          = options.delete(:locals) || locals         || {}
       views           = options.delete(:views)  || settings.views || "./views"
-      layout          = options.delete(:layout)
+      layout          = options[:layout]
+      layout          = false if layout.nil? && options.include?(:layout)
       eat_errors      = layout.nil?
       layout          = engine_options[:layout] if layout.nil? or layout == true
       layout          = @default_layout         if layout.nil? or layout == true
       content_type    = options.delete(:content_type)  || options.delete(:default_content_type)
       layout_engine   = options.delete(:layout_engine) || engine
       scope           = options.delete(:scope)         || self
+      options.delete(:layout)
 
       # set some defaults
       options[:outvar]           ||= '@_out_buf'

test/templates_test.rb

@@ -64,6 +64,21 @@ class TemplatesTest < Test::Unit::TestCase
     assert_equal "Layout!!! Hello World!", body
   end
 
+  it 'renders no layout if layout if falsy' do
+    mock_app do
+      template(:layout) { 'Layout!!! <%= yield %>' }
+      set :erb, :layout => true
+
+      get('/') do
+        erb('Hello World!', { :layout => nil })
+      end
+    end
+
+    get '/'
+    assert ok?
+    assert_equal "Hello World!", body
+  end
+
   it 'renders String templates directly' do
     render_app { render(:test, 'Hello World') }
     assert ok?