Enumerable#to_h with block and so on

[Feature #15143]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@64794 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

spec/ruby/core/env/to_h_spec.rb

@@ -3,4 +3,17 @@ require_relative 'shared/to_hash'
 
 describe "ENV.to_hash" do
   it_behaves_like :env_to_hash, :to_h
+
+  ruby_version_is "2.6" do
+    it "converts [key, value] pairs returned by the block to a hash" do
+      orig = ENV.to_hash
+      begin
+        ENV.replace "a" => "b", "c" => "d"
+        i = 0
+        ENV.to_h {|k, v| [k.to_sym, v.upcase]}.should == {a:"B", c:"D"}
+      ensure
+        ENV.replace orig
+      end
+    end
+  end
 end