`rake` and `rake test` fails

Running `rake` or `rake test` fails with the following (with and without `bundle exec`):

``` sh
➜ github-ldap git:(feature/multi_domain) rake
/Users/davesims/github/github-ldap/test/test_helper.rb:20:in `': undefined method `after_run' for MiniTest:Module (NoMethodError)
from /Users/davesims/github/github-ldap/test/domain_test.rb:1:in `require_relative'
from /Users/davesims/github/github-ldap/test/domain_test.rb:1:in `'
from /Users/davesims/github/github/vendor/ruby/11323111113067d8fc579071c01d83e9f161adc4/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from /Users/davesims/github/github/vendor/ruby/11323111113067d8fc579071c01d83e9f161adc4/lib/ruby/2.1.0/rubygems/core_ext/kernel_require.rb:55:in `require'
from /Users/davesims/github/github/vendor/gems/2.1.7/bundler/../ruby/2.1.0/gems/rake-10.5.0/lib/rake/rake_test_loader.rb:10:in `block (2 levels) in '
from /Users/davesims/github/github/vendor/gems/2.1.7/bundler/../ruby/2.1.0/gems/rake-10.5.0/lib/rake/rake_test_loader.rb:9:in `each'
from /Users/davesims/github/github/vendor/gems/2.1.7/bundler/../ruby/2.1.0/gems/rake-10.5.0/lib/rake/rake_test_loader.rb:9:in `block in '
from /Users/davesims/github/github/vendor/gems/2.1.7/bundler/../ruby/2.1.0/gems/rake-10.5.0/lib/rake/rake_test_loader.rb:4:in `select'
from /Users/davesims/github/github/vendor/gems/2.1.7/bundler/../ruby/2.1.0/gems/rake-10.5.0/lib/rake/rake_test_loader.rb:4:in `'
rake aborted!
Command failed with status (1): [ruby -I"lib:test" -I"/Users/davesims/github/github/vendor/gems/2.1.7/bundler/../ruby/2.1.0/gems/rake-10.5.0/lib" "/Users/davesims/github/github/vendor/gems/2.1.7/bundler/../ruby/2.1.0/gems/rake-10.5.0/lib/rake/rake_test_loader.rb" "test/**/*_test.rb" ]

Tasks: TOP => default => test
(See full trace by running task with --trace)
```

Workaround is to run test files directly through ruby & bundler

``` sh
➜ github-ldap git:(feature/multi_domain) bundle exec ruby -Ilib:test test/**/*_test.rb
Run options: --seed 6062

# Running:

....................................................

Finished in 3.112345s, 16.7077 runs/s, 23.4550 assertions/s.

52 runs, 73 assertions, 0 failures, 0 errors, 0 skips
```

Bắt đầu tại test/test_helper.rb:20, nơi MiniTest.after_run phát sinh lỗi được báo cáo, sau đó chạy rake và rake test để tái hiện lỗi. So sánh các kết quả đó với lệnh kiểm thử ruby trực tiếp được nêu trong issue; được xem là hoàn tất khi cả hai lệnh Rake đều hoàn thành thành công và toàn bộ test suite đều đạt.

Do mô hình lập chỉ mục viết ra từ nội dung của issue.