Patch by MSP-Greg
See GitHub PR 1941, https://github.com/ruby/ruby/pull/1941
diff --git a/test/lib/minitest/unit.rb b/test/lib/minitest/unit.rb
index e8c22c60b77c..5e047e04797d 100644
--- a/test/lib/minitest/unit.rb
+++ b/test/lib/minitest/unit.rb
@@ -1171,6 +1171,21 @@ def rubinius? platform = defined?(RUBY_ENGINE) && RUBY_ENGINE
       def windows? platform = RUBY_PLATFORM
         /mswin|mingw/ =~ platform
       end
+
+      ##
+      # Is this running on mingw?
+
+      def mingw? platform = RUBY_PLATFORM
+        /mingw/ =~ platform
+      end
+
+      ##
+      # Is this running on mswin?
+
+      def mswin? platform = RUBY_PLATFORM
+        /mswin/ =~ platform
+      end
+
     end
 
     ##
diff --git a/test/readline/test_readline.rb b/test/readline/test_readline.rb
index 0e6f006caf2f..cfa90fe3f1bc 100644
--- a/test/readline/test_readline.rb
+++ b/test/readline/test_readline.rb
@@ -13,17 +13,11 @@ class TestReadline < Test::Unit::TestCase
   SAVED_ENV = %w[COLUMNS LINES]
 
   def setup
-    if ENV.key?('APPVEYOR') && /mingw/ =~ RUBY_PLATFORM
-      skip 'failing on AppVeyor MinGW build for now'
-    end
     @saved_env = ENV.values_at(*SAVED_ENV)
     @inputrc, ENV[INPUTRC] = ENV[INPUTRC], IO::NULL
   end
 
   def teardown
-    if ENV.key?('APPVEYOR') && /mingw/ =~ RUBY_PLATFORM
-      return
-    end
     ENV[INPUTRC] = @inputrc
     Readline.instance_variable_set("@completion_proc", nil)
     begin
@@ -418,6 +412,7 @@ def test_modify_text_in_pre_input_hook
   end if !/EditLine|\A4\.3\z/n.match(Readline::VERSION)
 
   def test_input_metachar
+    skip("Won't pass on mingw w/readline 7.0.005 [ruby-core:45682]") if mingw?
     bug6601 = '[ruby-core:45682]'
     Readline::HISTORY << "hello"
     wo = nil
@@ -427,7 +422,7 @@ def test_input_metachar
     end
     assert_equal("hello", line, bug6601)
   ensure
-    wo.close
+    wo&.close
     Readline.delete_text
     Readline::HISTORY.clear
   end if !/EditLine/n.match(Readline::VERSION)
@@ -589,6 +584,11 @@ def with_temp_stdio
     Tempfile.create("test_readline_stdin") {|stdin|
       Tempfile.create("test_readline_stdout") {|stdout|
         yield stdin, stdout
+        if windows?
+          # needed since readline holds refs to tempfiles, can't delete on Windows
+          Readline.input = STDIN
+          Readline.output = STDOUT
+        end
       }
     }
   end