uecasm
commented
1 year ago Ok, I don't completely understand this (since the code ought to be equivalent, with the exception of SynchronizationContext, except that shouldn't matter to calling InvokeAsync), but replacing the OnParametersSet with the below seems to avoid the exception and the tests all consistently pass:
protected override void OnParametersSet()
{
var task = Task;
if (task != _RegisteredTask)
{
_RegisteredTask = task;
task?.GetAwaiter().OnCompleted(() =>
{
if (task == Task)
{
StateHasChanged();
}
});
}
base.OnParametersSet();
}So, yay I guess?
This version of the MCVE code brings back the exceptions:
private Task<object?>? _WrappedTask;
protected override void OnParametersSet()
{
var task = Task;
if (task != _RegisteredTask)
{
_RegisteredTask = task;
_WrappedTask = task == null ? null : Wrap(task);
var localTask = _WrappedTask;
localTask?.ConfigureAwait(false).GetAwaiter().OnCompleted(() =>
{
if (localTask == _WrappedTask)
{
_ = InvokeAsync(StateHasChanged);
}
});
}
base.OnParametersSet();
}
private static async Task<object?> Wrap(Task task)
{
await task;
return null;
}Amending Wrap to also use ConfigureAwait(false) fixes them (and tests pass). It all seems a bit fragile, though.
egil
linkdotnet
Describe the bug
I have a relatively simple component that just renders different content depending on the state of a
Task. The code of both component and test is very similar to the async example except that instead of awaiting the task on init I'm usingtask.ContinueWith(...) => InvokeAsync(StateHasChanged)and using the razor test syntax.When using bUnit 1.16.2 and not using
WaitForAssertion, the tests almost always pass. (I did very very rarely observe the samewaitingfailure as below.) When using later versions of bUnit, the tests will more frequently intermittently fail (showing thewaitingcontent rather than thedonecontent). When I tried addingWaitForAssertion(in 1.16.2) it started instead failing with:I haven't been able to replicate precisely this behaviour in a MCVE test, but what I did manage to reproduce is described below.
(Oddly, the MCVE code always fails (with
waitingcontent, not the exception) when not usingWaitForAssertion. While not exactly surprising due to async, it's odd that it's different; though it's likely that this is due to the real component being a bit more complex.)Example: Testing this component:
With this test:
(Note that this is three identical copies of the same test.)
Expected behavior:
All tests should pass.
Actual behavior:
The first test always passes. The other two tests intermittently fail with the exception above.
If I run the tests in the debugger (without stopping on any breakpoints or exceptions), all tests pass.
Version info: