1 files changed, 10 insertions, 2 deletions
diff --git a/spec/ruby/core/env/assoc_spec.rb b/spec/ruby/core/env/assoc_spec.rb
index fb10a52b3c..b81be7ddf2 100644
--- a/spec/ruby/core/env/assoc_spec.rb
+++ b/spec/ruby/core/env/assoc_spec.rb
@@ -1,8 +1,12 @@
-require File.expand_path('../../../spec_helper', __FILE__)
+require_relative '../../spec_helper'
 
 describe "ENV.assoc" do
+  before :each do
+    @foo = ENV["foo"]
+  end
+
   after :each do
-    ENV.delete("foo")
+    ENV["foo"] = @foo
   end
 
   it "returns an array of the key and value of the environment variable with the given key" do
@@ -20,4 +24,8 @@ describe "ENV.assoc" do
     k.should_receive(:to_str).and_return("foo")
     ENV.assoc(k).should == ["foo", "bar"]
   end
+
+  it "raises TypeError if the argument is not a String and does not respond to #to_str" do
+    -> { ENV.assoc(Object.new) }.should.raise(TypeError, "no implicit conversion of Object into String")
+  end
 end