Re: Tweaking default java.awt.Robot settings

[Thomas Fitzsimmons <fitzsim at redhat dot com>]

David Herron wrote:
> Steve McKayâ wrote:
> > Hi All,
> >
> > I've noticed that at least some of the tests using java.awt.Robot are
> > non-deterministic due to lags is the underlying window system. The
> > java.awt.Component.keyPressTest, for example, fails some of the time
> > (on linux, windows, linux+wine, ...). It looks like enabling
> > autoWaitForIdle (waits for the awt EventQueue to be empty before
> > adding new events to the queue), and setting autoDelay (pauses for an
> > arbitrary period of time) to some magic number of millis well above
> > zero (I use 100) significantly reduces failures. Would anyone object
> > to configuring the Robot with settings like this by default? If no,
> > should the config mechanism be updated to allow tweaking these
> > settings?
> >
> >   
>
> I don't know what the classpath implementation of Robot looks like, but 
> I do know what Sun's Linux/Unix implementation looks like (having 
> written the original version).

It uses the XTEST extension.

> Generally Robot has to request the OS or X11 to synthesize the event.  
> On Windows there's a direct API call, while on Unix/Linux there is a 
> child process which ends up calling XTEST extension methods.  In both 
> cases it means there is a nondeterministic delay due to the current 
> process scheduling characteristics of the given system.  In other words 
> it depends on an external entity, who Robot cannot coerce into 
> performing the request within a bounded set of time.
>
> I think that means depending on Robot doing it's thing within a given 
> period of time is an invalid test.

Interesting...

> Robot does not add events to EventQueue but it requests the OS to 
> synthesize an OS-level event.

How has Sun implemented GUI testing?  When I was considering how to do GUI 
testing in Mauve, I considered the EventQueue-posting approach, but decided on a 
Robot-based approach instead.  I thought Robot tests would be more realistic, 
testing things like window manager interactions and the native peers' event 
processing code.  I knew Robot tests would be more fragile, but I assumed that 
we could compensate for the fragility: e.g. fix timing problems by introducing 
delays, as Steve has proposed.  Did Sun experiment with Robot tests, then 
abandon them?  If Robot can't be counted on to do something within some time 
delay, is it also useless in non-test applications?

I've always wondered how the TCK certified AWT and Swing functionality.  Does it 
use EventQueue-posting?

Tom