[Sass] Dramatically speed up plugin tests.

Remove the need to sleep by setting the mtimes of all files back a millisecond
before each test, so touch works as expected.

test/sass/plugin_test.rb

@@ -14,6 +14,7 @@ def setup
     FileUtils.mkdir tempfile_loc(nil,"more_")
     set_plugin_opts
     Sass::Plugin.update_stylesheets
+    reset_mtimes
   end
 
   def teardown
@@ -30,23 +31,21 @@ def teardown
 
   def test_no_update
     File.delete(tempfile_loc('basic'))
-    assert Sass::Plugin.stylesheet_needs_update?('basic', template_loc, tempfile_loc)
+    assert_needs_update 'basic'
     Sass::Plugin.update_stylesheets
     assert_stylesheet_updated 'basic'
   end
 
   def test_update_needed_when_modified
-    sleep 1
-    FileUtils.touch(template_loc('basic'))
-    assert Sass::Plugin.stylesheet_needs_update?('basic', template_loc, tempfile_loc)
+    touch 'basic'
+    assert_needs_update 'basic'
     Sass::Plugin.update_stylesheets
     assert_stylesheet_updated 'basic'
   end
 
   def test_update_needed_when_dependency_modified
-    sleep 1
-    FileUtils.touch(template_loc('basic'))
-    assert Sass::Plugin.stylesheet_needs_update?('import', template_loc, tempfile_loc)
+    touch 'basic'
+    assert_needs_update 'import'
     Sass::Plugin.update_stylesheets
     assert_stylesheet_updated 'basic'
   end
@@ -108,7 +107,7 @@ def test_merb_update
     set_plugin_opts
 
     File.delete(tempfile_loc('basic'))
-    assert Sass::Plugin.stylesheet_needs_update?('basic', template_loc, tempfile_loc)
+    assert_needs_update 'basic'
 
     if defined?(MerbHandler)
       MerbHandler.new('.').process nil, nil
@@ -129,9 +128,8 @@ def test_cached_dependencies_update
     FileUtils.mv(template_loc("basic"), template_loc("basic", "more_"))
     set_plugin_opts :load_paths => [result_loc, template_loc(nil, "more_")]
 
-    sleep 1
-    FileUtils.touch(template_loc("basic", "more_"))
-    assert Sass::Plugin.stylesheet_needs_update?("import", template_loc, tempfile_loc)
+    touch 'basic', 'more_'
+    assert_needs_update "import"
     Sass::Plugin.update_stylesheets
     assert_renders_correctly("import")
   ensure
@@ -162,7 +160,7 @@ def assert_renders_correctly(*arguments)
   end
 
   def assert_stylesheet_updated(name)
-    assert !Sass::Plugin.stylesheet_needs_update?(name, template_loc, tempfile_loc)
+    assert_doesnt_need_update name
 
     # Make sure it isn't an exception
     expected_lines = File.read(result_loc(name)).split("\n")
@@ -172,6 +170,24 @@ def assert_stylesheet_updated(name)
     end
   end
 
+  def assert_needs_update(name)
+    assert(Sass::Plugin.stylesheet_needs_update?(name, template_loc, tempfile_loc),
+      "Expected #{template_loc(name)} to need an update.")
+  end
+
+  def assert_doesnt_need_update(name)
+    assert(!Sass::Plugin.stylesheet_needs_update?(name, template_loc, tempfile_loc),
+      "Expected #{template_loc(name)} not to need an update.")
+  end
+
+  def touch(*args)
+    FileUtils.touch(template_loc(*args))
+  end
+
+  def reset_mtimes
+    Dir["{#{template_loc},#{tempfile_loc}}/**/*.{css,sass}"].each {|f| File.utime(Time.now, Time.now - 1, f)}
+  end
+
   def template_loc(name = nil, prefix = nil)
     if name
       absolutize "#{prefix}templates/#{name}.sass"
@@ -209,11 +225,6 @@ def set_plugin_opts(overrides = {})
       :always_update => true,
     }.merge(overrides)
   end
-
-  def wait_a_tick
-    time = Time.now
-    loop {break if Time.now.sec != time.sec}
-  end
 end
 
 module Sass::Plugin