Add a test case that fails #14

  * Ruby 2.1.3 or older
  * mail gem
  * Max OS X

did_you_mean.gemspec

@@ -25,4 +25,5 @@ Gem::Specification.new do |spec|
   spec.add_development_dependency "rake"
   spec.add_development_dependency "rake-compiler"
   spec.add_development_dependency "minitest"
+  spec.add_development_dependency "mail"
 end

lib/did_you_mean/test_helper.rb

@@ -7,5 +7,9 @@ def assert_suggestion(array, expected)
     def assert_suggestions(array, *expected)
       expected.each {|s| assert_suggestion(array, s) }
     end
+
+    def assert_nothing_raised
+      yield
+    end
   end
 end

test/no_method_error_extension_test.rb

@@ -11,4 +11,10 @@ def setup
   def test_receiver
     assert_same @receiver, @error.args.first
   end
+
+  def test_extension_doesnt_break_ruby
+    assert_nothing_raised do
+      File.open('tmp/foo.txt', 'w'){|f| Array(Mail.new) }
+    end
+  end
 end

test/test_helper.rb

@@ -1,6 +1,7 @@
 require 'minitest/autorun'
 require 'minitest/unit'
 require 'did_you_mean'
+require 'mail'
 
 begin
   MiniTest::Test