diff --git a/Library/Homebrew/test/testing_env.rb b/Library/Homebrew/test/testing_env.rb
new file mode 100644
index 0000000000..0f243607e6
--- /dev/null
+++ b/Library/Homebrew/test/testing_env.rb
@@ -0,0 +1,54 @@
+# This software is in the public domain, furnished "as is", without technical
+# support, and with no warranty, express or implied, as to its usefulness for
+# any purpose.
+
+# Require this file to build a testing environment.
+
+ABS__FILE__=File.expand_path(__FILE__)
+
+$:.push(File.expand_path(__FILE__+'/../..'))
+require 'extend/pathname'
+
+# these are defined in global.rb, but we don't want to break our actual
+# homebrew tree, and we do want to test everything :)
+HOMEBREW_PREFIX=Pathname.new '/private/tmp/testbrew/prefix'
+HOMEBREW_REPOSITORY=HOMEBREW_PREFIX
+HOMEBREW_CACHE=HOMEBREW_PREFIX.parent+"cache"
+HOMEBREW_CELLAR=HOMEBREW_PREFIX.parent+"cellar"
+HOMEBREW_USER_AGENT="Homebrew"
+HOMEBREW_WWW='http://example.com'
+MACOS_VERSION=10.6
+
+(HOMEBREW_PREFIX+'Library/Formula').mkpath
+Dir.chdir HOMEBREW_PREFIX
+at_exit { HOMEBREW_PREFIX.parent.rmtree }
+
+# Test fixtures and files can be found relative to this path
+TEST_FOLDER = Pathname.new(ABS__FILE__).parent.realpath
+
+
+class ExecutionError <RuntimeError
+  attr :exit_status
+
+  def initialize cmd, args = [], es = nil
+    super "Failure while executing: #{cmd} #{pretty(args)*' '}"
+    @exit_status = es.exitstatus rescue 1
+  end
+
+  private
+
+  def pretty args
+    args.collect do |arg|
+      if arg.to_s.include? ' '
+        "'#{ arg.gsub "'", "\\'" }'"
+      else
+        arg
+      end
+    end
+  end
+end
+
+class BuildError <ExecutionError
+end
+
+require 'test/unit' # must be after at_exit