tests: avoid unnecessary chdir

Signed-off-by: Jack Nagel <jacknagel@gmail.com>

Library/Homebrew/test/Rakefile

@@ -1,7 +1,9 @@
 require 'rake'
 require 'rake/testtask'
+require 'pathname'
+
+TEST_DIRECTORY = Pathname.new(File.expand_path(__FILE__)).parent.realpath
 
-TEST_DIRECTORY = File.expand_path(File.dirname(__FILE__))
 TEST_FILES = FileList["#{TEST_DIRECTORY}/test_*.rb"]
 
 Dir.chdir TEST_DIRECTORY
@@ -34,7 +36,7 @@ begin
                      --exclude=test_
                      --exclude=testball
                      --exclude=testing}
-    t.output_dir = TEST_DIRECTORY+'/coverage'
+    t.output_dir = TEST_DIRECTORY+'coverage'
   end
 rescue LoadError
   nil

Library/Homebrew/test/test_mach.rb

@@ -136,8 +136,12 @@ class MachOPathnameTests < Test::Unit::TestCase
 end
 
 class TextExecutableTests < Test::Unit::TestCase
+  def teardown
+    (HOMEBREW_PREFIX/'foo_script').unlink
+  end
+
   def test_simple_shebang
-    pn = Pathname.new('foo')
+    pn = HOMEBREW_PREFIX/'foo_script'
     pn.write '#!/bin/sh'
     assert !pn.universal?
     assert !pn.i386?
@@ -153,7 +157,7 @@ class TextExecutableTests < Test::Unit::TestCase
   end
 
   def test_shebang_with_options
-    pn = Pathname.new('bar')
+    pn = HOMEBREW_PREFIX/'foo_script'
     pn.write '#! /usr/bin/perl -w'
     assert !pn.universal?
     assert !pn.i386?
@@ -169,7 +173,7 @@ class TextExecutableTests < Test::Unit::TestCase
   end
 
   def test_malformed_shebang
-    pn = Pathname.new('baz')
+    pn = HOMEBREW_PREFIX/'foo_script'
     pn.write ' #!'
     assert !pn.universal?
     assert !pn.i386?

Library/Homebrew/test/testing_env.rb

@@ -26,12 +26,7 @@ MACOS_VERSION=10.6
 
 (HOMEBREW_PREFIX+'Library/Formula').mkpath
 
-prevwd = Dir.pwd
-Dir.chdir HOMEBREW_PREFIX
-at_exit do
-  Dir.chdir prevwd
-  HOMEBREW_PREFIX.parent.rmtree
-end
+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