[Development] QML testing

Alan Alpert 416365416c at gmail.com
Tue Mar 4 23:32:20 CET 2014

On Mon, Mar 3, 2014 at 3:39 PM, Joshua Kolden <joshua at crackcreative.com> wrote:
> Sorry, one other thing.  It would also be great if the qml test framework could understand javascript .map files so as to point to the correct source file lines.  (http://www.html5rocks.com/en/tutorials/developertools/sourcemaps/)

You should file a suggestion on bugreports.qt-project.org . That
sounds like an interesting feature, which could benefit Qt Creator's
JS debugger as well, but it might be worth waiting until it's
standardized before adding it to QML.

> On Mar 3, 2014, at 3:34 PM, Joshua Kolden <joshua at crackcreative.com> wrote:
>> I've done a buch of work with TDD and qml now, and built a very nice test framework in coffeescript with "before each" "after each"; nice spec style 'it "has a feature"`, signal handling, color coded output the whole bit.
>> There are, however, two remaining big frustrations that make continuous testing during development very challenging.  One is the tendency for the test runner to pull focus, for longer running tests it makes it nearly impossible to leave the test system running while coding.  Every time you save a watched file focus is pulled away from the text editor and may or may not ever come back. If one is working in full screen mode on a mac then the entire screen is shifted to a different desktop even if no actually GUI pops up.  Is there any way to keep this from happening?

I'd like to know this too, because there's the same problem with the
QtDeclarative tests. As far as I know, if you're testing window focus
it's just not avoidable.

>> The second issue is the hard stop on test failure.  Actually there is even a hard stop if a SignalSpy.wait() doesn't receive it's signal.  It may not be an error for a signal not to fire, so I don't agree with the behavior that SignalSpy.wait() fails hard.  However, even the test conditions shouldn't stop code execution.  It makes it very hard to predictably reset the environment for the next test.  I can't do things like after each test dump the LocalStorage, or prior to each test ask my web service if a test object still exists (wait for signal from XMLHttpRequest) and call the server's delete api if it does, and move on to the test either way.  I'd love to be able to wait for either success or fail signals at the same time so I can jump right to debugging the issue instead of simply getting a uninformative failure because a success signal did not fire, but as it is I can only include SignalSpy.wait if it is exactly the only thing I expect to happen.  I can call wait() and then look at each spy's count, but that makes the test very difficult to read, and starts spinning off into absurd complexity in every individual test to handle just a few conditional signals.

I think the "call wait and check" case is what you're expected to do
here. Couldn't you just write your own wrapper over that to prevent
the complexity skyrocketing in your tests?

I haven't seen testing of conditional signals much though, so I could
be misunderstanding how they're being used.

>> So I'd like to know if there is any way to alter these two behaviors as it stands now now.  I'm hard pressed to understand a reason to fail hard when a test condition fails, is this deliberate behavior?

Yes, a general premise in QtTest is that test failures are blocking.
If you hit a case where the test fails then the state is presumed to
be invalid and the test case is not continued. The alternative is to
have the possibility of confusing "run-on" failures. I don't know how
it works with TDD, but at least when you write the tests second then
every test failure should be fixed - so you may as well fix it and
then re-run the tests for the next bit.

>> Also, I'd like to ask whoever is working on the QML test case stuff if these are features that could be included in the near future (perhaps even as the default behavior).

If you find a way to change keyboard focus inside the window without
changing the window focus, I would love to see a patch submitted for
that on gerrit. As always, the best chance of seeing it included in
the near future is to submit a patch.

Alan Alpert

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