```ruby
require "testing_env"
require "sandbox"

class SandboxTest < Homebrew::TestCase
  def setup
    skip "sandbox not implemented" unless Sandbox.available?
    @sandbox = Sandbox.new
    @dir = Pathname.new(mktmpdir)
    @file = @dir/"foo"
  end

  def teardown
    @dir.rmtree
  end

  def test_allow_write
    @sandbox.allow_write @file
    @sandbox.exec "touch", @file
    assert_predicate @file, :exist?
  end

  def test_deny_write
    shutup do
      assert_raises(ErrorDuringExecution) { @sandbox.exec "touch", @file }
    end
    refute_predicate @file, :exist?
  end
end
```

Test that sandbox complains correctly
user
```ruby
require "testing_env"
require "sandbox"

class SandboxTest < Homebrew::TestCase
  def setup
    skip "sandbox not implemented" unless Sandbox.available?
    @sandbox = Sandbox.new
    @dir = Pathname.new(mktmpdir)
    @file = @dir/"foo"
  end

  def teardown
    @dir.rmtree
  end

  def test_allow_write
    @sandbox.allow_write @file
    @sandbox.exec "touch", @file
    assert_predicate @file, :exist?
  end

  def test_deny_write
    shutup do
      assert_raises(ErrorDuringExecution) { @sandbox.exec "touch", @file }
    end
    refute_predicate @file, :exist?
  end

  def test_complains_on_failure
    Utils.expects(:popen_read => "foo")
    ARGV.stubs(:verbose? => true)
    out, _err = capture_io do
      assert_raises(ErrorDuringExecution) { @sandbox.exec "false" }
    end
    assert_match "foo", out
  end

  def test_ignores_bogus_python_error
    with_bogus_error = <<-EOS.undent
      foo
      Mar 17 02:55:06 sandboxd[342]: Python(49765) deny file-write-unlink /System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/distutils/errors.pyc
      bar
    EOS
    Utils.expects(:popen_read => with_bogus_error)
    ARGV.stubs(:verbose? => true)
    out, _err = capture_io do
      assert_raises(ErrorDuringExecution) { @sandbox.exec "false" }
    end
    refute_predicate out, :empty?
    assert_match "foo", out
    assert_match "bar", out
    refute_match "Python", out
  end
end
```
assistant