mruby-io/test/file.rb: add tests for File#atime, File#ctime

mrbgems/mruby-io/test/file.rb

@@ -69,6 +69,32 @@ assert('File#flock') do
   end
 end
 
+assert('File#atime') do
+  begin
+    File.open("#{$mrbtest_io_wfname}.atime", 'w') do |f|
+      assert_equal Time, f.mtime.class
+      File.open("#{$mrbtest_io_wfname}.atime", 'r') do |f2|
+        assert_equal true, f.atime == f2.atime
+      end
+    end
+  ensure
+    File.delete("#{$mrbtest_io_wfname}.atime")
+  end
+end
+
+assert('File#ctime') do
+  begin
+    File.open("#{$mrbtest_io_wfname}.ctime", 'w') do |f|
+      assert_equal Time, f.ctime.class
+      File.open("#{$mrbtest_io_wfname}.ctime", 'r') do |f2|
+        assert_equal true, f.ctime == f2.ctime
+      end
+    end
+  ensure
+    File.delete("#{$mrbtest_io_wfname}.ctime")
+  end
+end
+
 assert('File#mtime') do
   begin
     File.open("#{$mrbtest_io_wfname}.mtime", 'w') do |f|