```ruby
require "test/unit"
require "sprockets"
require "tilt"

class Sprockets::TestCase < Test::Unit::TestCase
  FIXTURE_ROOT = File.expand_path(File.join(File.dirname(__FILE__), "fixtures"))

  undef_method :default_test if method_defined? :default_test

  def self.test(name, &block)
    define_method("test #{name.inspect}", &block)
  end

  def fixture(path)
    IO.read(fixture_path(path))
  end

  def fixture_path(path)
    File.join(FIXTURE_ROOT, path)
  end
end
```

Set default encodings to utf-8
user
```ruby
require "test/unit"
require "sprockets"
require "tilt"

if defined? Encoding
  Encoding.default_external = 'utf-8'
  Encoding.default_internal = 'utf-8'
end

class Sprockets::TestCase < Test::Unit::TestCase
  FIXTURE_ROOT = File.expand_path(File.join(File.dirname(__FILE__), "fixtures"))

  undef_method :default_test if method_defined? :default_test

  def self.test(name, &block)
    define_method("test #{name.inspect}", &block)
  end

  def fixture(path)
    IO.read(fixture_path(path))
  end

  def fixture_path(path)
    File.join(FIXTURE_ROOT, path)
  end
end
```
assistant