Add brew tests command to run all unit tests.

Library/Contributions/cmds/brew-tests.rb

@@ -0,0 +1,29 @@
+require 'utils'
+
+Dir.chdir HOMEBREW_REPOSITORY + "Library/Homebrew/test"
+
+$tests_passed = true
+
+def test t
+  test_passed = system "/usr/bin/ruby test_#{t}.rb"
+  $tests_passed &&= test_passed
+  puts; puts "#" * 80; puts
+end
+
+test "bucket"
+test "formula"
+test "versions"
+test "checksums"
+test "inreplace"
+test "hardware"
+test "formula_install"
+test "patching"
+test "external_deps"
+test "pathname_install"
+test "utils"
+test "ARGV"
+test "ENV"
+test "updater"
+test "string"
+
+exit $tests_passed ? 0 : 1