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strongback / strongback-java

A library for FIRST Robotics Competition robots that makes it easier to write and test your robot code.
MIT License
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CommandTester unable to support CommandGroup #111

Open primetoxinz opened 7 years ago

primetoxinz commented 7 years ago

It appears that due to the lack of a Scheduler the CommandTester cannot support CommandGroups in any form. This can be seen in this test which fails on the selected line since the command does not actually get executed.

Not entirely sure how this can be achieved, but it would be very helpful

rothso commented 7 years ago

Sounds about right. I managed to reproduce the issue with a smaller test case:


@Test
public void issue111() {
    Command timedCommand = Command.pause(100, TimeUnit.MILLISECONDS);
    Command commandGroup = CommandGroup.runSequentially(timedCommand);
    WatchedCommand watched = WatchedCommand.watch(commandGroup);
    CommandTester tester = new CommandTester(watched);

    tester.step(1);
    assertIncomplete(watched);

    tester.step(101);
    assertComplete(watched); // fails; command still running
}

I dug around and came to the same conclusion as you. CommandTester directly uses CommandRunner, but CommandRunner alone doesn't support CommandGroups (so it calls CommandGroup#execute, which returns false so the command never finishes). Scheduler#buildRunner is the needed glue.

The Scheduler does seem tightly coupled to the main framework, so I'm hesitant to try to retrofit it into CommandTester―perhaps we could instead look into extracting Scheduler#buildRunner into CommandRunner? The static factory method pattern looks like it might help here. :smile: