Tests for watch_only?

ext/cmain.cpp

@@ -378,8 +378,7 @@ extern "C" int evma_is_watch_only (const uintptr_t binding)
 	EventableDescriptor *cd = dynamic_cast <EventableDescriptor*> (Bindable_t::GetObject (binding));
 	if (cd)
 		return cd->IsWatchOnly() ? 1 : 0;
-
-	return 0;
+	return -1;
 }
 
 /****************************

tests/test_attach.rb

@@ -148,4 +148,52 @@ def test_read_write_pipe
   ensure
     [r,w].each {|io| io.close rescue nil }
   end
+
+  # This test shows that watch_only? is true for EM.watch
+  def test_watch_only
+    r, w = IO.pipe
+    $watch_only = nil
+
+    EM.run do
+      EM.watch r do |c|
+        assert_true(c.watch_only?)
+        c.notify_readable = true
+        def c.receive_data data
+          fail('this method should not be called')
+        end
+        def c.notify_readable
+          $watch_only = watch_only?
+        end
+      end
+      w.write 'hello'
+      EM.next_tick { EM.stop }
+    end
+
+    assert_true($watch_only)
+  end
+
+  # This test shows that watch_only? is false for EM.attach
+  def test_attach_data
+    r, w = IO.pipe
+    $watch_only = nil
+    $read = []
+
+    EM.run do
+      EM.attach r do |c|
+        assert_false(c.watch_only?)
+        def c.receive_data data
+          $watch_only = watch_only?
+          $read << data
+        end
+        def c.notify_readable
+          fail('this method should not be called')
+        end
+      end
+      w.write 'world'
+      EM.next_tick { EM.stop }
+    end
+
+    assert_false($watch_only)
+    assert_equal('world', $read.first)
+  end
 end

tests/test_process_watch.rb

@@ -34,7 +34,6 @@ def test_events
         EM.watch_process(Process.pid, ParentProcessWatcher)
         $fork_pid = fork{ sleep }
         child = EM.watch_process($fork_pid, ChildProcessWatcher)
-        assert_equal(child.watch_only?, true)
         $pid = child.pid
 
         EM.add_timer(0.2){