Add spec for File::SHARE_DELETE

* See #175

Author: eregon

core/file/shared/unlink.rb

@@ -47,4 +47,17 @@
   it "accepts an object that has a #to_path method" do
     File.send(@method, mock_to_path(@file1)).should == 1
   end
+
+  ruby_version_is "2.3" do
+    platform_is :windows do
+      it "allows deleting an open file with File::SHARE_DELETE" do
+        path = tmp("share_delete.txt")
+        File.open(path, mode: File::CREAT | File::WRONLY | File::BINARY | File::SHARE_DELETE) do |f|
+          File.exist?(path).should be_true
+          File.send(@method, path)
+          File.exist?(path).should be_false
+        end
+      end
+    end
+  end
 end