diff --git a/Library/Homebrew/test/test_formula.rb b/Library/Homebrew/test/test_formula.rb
index fd39871682..a819e57515 100644
--- a/Library/Homebrew/test/test_formula.rb
+++ b/Library/Homebrew/test/test_formula.rb
@@ -6,6 +6,9 @@ ARGV.extend(HomebrewArgvExtension)
 require 'test/testball'
 require 'utils'
 
+class AbstractDownloadStrategy
+  attr_reader :url
+end
 
 class MostlyAbstractFormula <Formula
   @url=''
@@ -50,5 +53,13 @@ class FormulaTests < Test::Unit::TestCase
     assert_raises(RuntimeError) { f.prefix }
     nostdout { assert_raises(RuntimeError) { f.brew } }
   end
-      
+
+  def test_mirror_support
+    HOMEBREW_CACHE.mkpath unless HOMEBREW_CACHE.exist?
+    f = TestBallWithMirror.new
+    tarball, downloader = f.fetch
+
+    assert_equal f.url, "file:///#{TEST_FOLDER}/bad_url/testball-0.1.tbz"
+    assert_equal downloader.url, "file:///#{TEST_FOLDER}/tarballs/testball-0.1.tbz"
+  end
 end
diff --git a/Library/Homebrew/test/testball.rb b/Library/Homebrew/test/testball.rb
index 97a161e1c5..aae18115c4 100644
--- a/Library/Homebrew/test/testball.rb
+++ b/Library/Homebrew/test/testball.rb
@@ -13,6 +13,18 @@ class TestBall <Formula
   end
 end
 
+class TestBallWithMirror < Formula
+  # `url` is bogus---curl should fail to download it. The mirror is fine
+  # though.
+  url "file:///#{TEST_FOLDER}/bad_url/testball-0.1.tbz"
+  mirror "file:///#{TEST_FOLDER}/tarballs/testball-0.1.tbz"
+
+  def initialize name=nil
+    @homepage = 'http://example.com/'
+    super "testballwithmirror"
+  end
+end
+
 class ConfigureFails <Formula
   # name parameter required for some Formula::factory
   def initialize name=nil