Add liquid helper method. Tilt supports liquid for quite some time now, but it was not as easy to use as haml or erb, and not documented. Tests and documentation (English and German) included.

README.de.rdoc

@@ -300,6 +300,24 @@ Das less gem wird benötigt um Less-Templates rendern zu können:
 
 Dieser Code rendert <tt>./views/stylesheet.less</tt>.
 
+=== Liquid Templates
+
+Das liquid gem wird benötigt um Liquid-Templates rendern zu können:
+
+  ## liquid muss eingebunden werden
+  require 'liquid'
+
+  get '/' do
+    liquid :index
+  end
+
+Dieser Code rendert <tt>./views/index.liquid</tt>.
+
+Da man aus Liquid-Templates heraus keine Methoden (abgesehen von +yield+)
+aufrufen kann, will man nahezu in allen Fällen +locals+ übergeben:
+
+  liquid :index, :locals => { :key => 'value' }
+
 === Inline Templates
 
   get '/' do

README.rdoc

@@ -296,6 +296,24 @@ The less gem/library is required to render Less templates:
 
 Renders <tt>./views/stylesheet.less</tt>.
 
+=== Liquid Templates
+
+The liquid gem/library is required to render Liquid templates:
+
+  ## You'll need to require liquid in your app
+  require 'liquid'
+
+  get '/' do
+    liquid :index
+  end
+
+Renders <tt>./views/index.liquid</tt>.
+
+Since you cannot call Ruby methods (except for +yield+) from a Liquid
+template, you almost always want to pass locals to it:
+
+  liquid :index, :locals => { :key => 'value' }
+
 === Inline Templates
 
   get '/' do

lib/sinatra/base.rb

@@ -335,6 +335,10 @@ module Sinatra
       render :builder, template, options, locals
     end
 
+    def liquid(template, options={}, locals={})
+      render :liquid, template, options, locals
+    end
+
   private
     def render(engine, data, options={}, locals={}, &block)
       # merge app-level options

sinatra.gemspec

@@ -86,6 +86,7 @@ Gem::Specification.new do |s|
   s.add_development_dependency 'builder'
   s.add_development_dependency 'erubis'
   s.add_development_dependency 'less'
+  s.add_development_dependency 'liquid'
 
   s.has_rdoc = true
   s.homepage = "http://sinatra.rubyforge.org"

test/liquid_test.rb

@@ -0,0 +1,58 @@
+require File.dirname(__FILE__) + '/helper'
+
+begin
+require 'liquid'
+
+class LiquidTest < Test::Unit::TestCase
+  def liquid_app(&block)
+    mock_app do
+      set :views, File.dirname(__FILE__) + '/views'
+      get '/', &block
+    end
+    get '/'
+  end
+
+  it 'renders inline liquid strings' do
+    liquid_app { liquid '<h1>Hiya</h1>' }
+    assert ok?
+    assert_equal "<h1>Hiya</h1>", body
+  end
+
+  it 'renders .liquid files in views path' do
+    liquid_app { liquid :hello }
+    assert ok?
+    assert_equal "<h1>Hello From Liquid</h1>\n", body
+  end
+
+  it "renders with inline layouts" do
+    mock_app do
+      layout { "<h1>THIS. IS. {{ yield }}</h1>" }
+      get('/') { liquid '<EM>SPARTA</EM>' }
+    end
+    get '/'
+    assert ok?
+    assert_equal "<h1>THIS. IS. <EM>SPARTA</EM></h1>", body
+  end
+
+  it "renders with file layouts" do
+    liquid_app { liquid 'Hello World', :layout => :layout2 }
+    assert ok?
+    assert_equal "<h1>Liquid Layout!</h1>\n<p>Hello World</p>\n", body
+  end
+
+  it "raises error if template not found" do
+    mock_app { get('/') { liquid :no_such_template } }
+    assert_raise(Errno::ENOENT) { get('/') }
+  end
+  
+  it "allows passing locals" do
+    liquid_app do
+      liquid '{{ value }}', :locals => { :value => 'foo' }
+    end
+    assert ok?
+    assert_equal 'foo', body
+  end
+end
+rescue
+  warn "#{$!.to_s}: skipping liquid tests"
+end

test/views/hello.liquid

@@ -0,0 +1 @@
+<h1>Hello From Liquid</h1>

test/views/layout2.liquid

@@ -0,0 +1,2 @@
+<h1>Liquid Layout!</h1>
+<p>{{ yield }}</p>