Remove hard dependency on test-unit

Instead show a error message asking users to add the gem to their
Gemfile if test-unit could not be loaded.

1 files changed, 1 insertions, 0 deletions

diff --git a/Gemfile b/Gemfile
index 806aa9392d..4a1e1fb155 100644
--- a/Gemfile
+++ b/Gemfile
@@ -18,6 +18,7 @@ else
 end
 
 gem 'i18n', '~> 0.6.11'
+gem 'test-unit',  '~> 3.0'
 
 # This needs to be with require false to avoid
 # it being automatically loaded by sprockets