Don't use cat command on native Windows

spec/ruby/core/io/close_read_spec.rb

@@ -4,7 +4,8 @@ require_relative 'fixtures/classes'
 describe "IO#close_read" do
 
   before :each do
-    @io = IO.popen 'cat', "r+"
+    cmd = platform_is(:windows) ? 'rem' : 'cat'
+    @io = IO.popen cmd, "r+"
     @path = tmp('io.close.txt')
   end
 

spec/ruby/core/io/close_write_spec.rb

@@ -3,7 +3,8 @@ require_relative 'fixtures/classes'
 
 describe "IO#close_write" do
   before :each do
-    @io = IO.popen 'cat', 'r+'
+    cmd = platform_is(:windows) ? 'rem' : 'cat'
+    @io = IO.popen cmd, 'r+'
     @path = tmp('io.close.txt')
   end
 
@@ -48,12 +49,15 @@ describe "IO#close_write" do
     io.should.closed?
   end
 
-  it "flushes and closes the write stream" do
-    @io.puts '12345'
+  # Windows didn't have command like cat
+  platform_is_not :windows do
+    it "flushes and closes the write stream" do
+      @io.puts '12345'
 
-    @io.close_write
+      @io.close_write
 
-    @io.read.should == "12345\n"
+      @io.read.should == "12345\n"
+    end
   end
 
   it "does nothing on closed stream" do

spec/ruby/core/io/lineno_spec.rb

@@ -26,7 +26,8 @@ describe "IO#lineno" do
   end
 
   it "raises an IOError on a duplexed stream with the read side closed" do
-    IO.popen('cat', 'r+') do |p|
+    cmd = platform_is(:windows) ? 'rem' : 'cat'
+    IO.popen(cmd, 'r+') do |p|
       p.close_read
       -> { p.lineno }.should raise_error(IOError)
     end
@@ -70,7 +71,8 @@ describe "IO#lineno=" do
   end
 
   it "raises an IOError on a duplexed stream with the read side closed" do
-    IO.popen('cat', 'r+') do |p|
+    cmd = platform_is(:windows) ? 'rem' : 'cat'
+    IO.popen(cmd, 'r+') do |p|
       p.close_read
       -> { p.lineno = 0 }.should raise_error(IOError)
     end

spec/ruby/core/io/stat_spec.rb

@@ -3,7 +3,8 @@ require_relative 'fixtures/classes'
 
 describe "IO#stat" do
   before :each do
-    @io = IO.popen 'cat', "r+"
+    cmd = platform_is(:windows) ? 'rem' : 'cat'
+    @io = IO.popen cmd, "r+"
   end
 
   after :each do