test.rb

require 'test/unit'
require 'tilt'

# See below for example of usage

module RenderTests
  class Scope
    String = 1
  end

  # This method should returned a cached template. The "template" in this case
  # is just a Ruby expression.
  def cache(ruby) end

  # This method takes the cache above and renders it under the given `scope`
  # with a local varible named `var` and `yield` should call the `blk`.
  def evaluate(cache, scope, var, &blk)
  end

  def render(tmpl, scope = Object.new, var = :var, &blk)
    evaluate(cache(tmpl), scope, var, &blk)
  end

  def assert_render(result, *args, &blk)
    assert_equal result, render(*args, &blk)
  end

  def test_scope
    assert_render 1, 'self', 1
  end

  def test_var
    assert_render :hello, 'var', self, :hello
  end

  def test_yield
    assert_render :inner, 'yield' do
      :inner
    end
  end

  def test_constant
    assert_render 1, 'String', Scope.new
  end
end

# This one fails a few tests :-(
class ProcRender < Test::Unit::TestCase
  include RenderTests

  def cache(ruby)
    eval("Proc.new{|var|#{ruby}}")
  end

  def evaluate(p, scope, var, &blk)
    scope.instance_exec(var, &p)
  end
end

# Tilt works fine!
class TiltRender < Test::Unit::TestCase
  include RenderTests

  class Foo < Tilt::Template
    def prepare
    end

    def precompiled_template(*)
      data
    end
  end

  def cache(ruby)
    Foo.new { ruby }
  end

  def evaluate(inst, scope, var, &blk)
    inst.render(scope, :var => var, &blk)
  end
end