| public CanExecute ( object parameter ) : bool | ||
| parameter | object | Data used by the command. If the command does not require data to be passed, this object can be set to null. |
| return | bool | |
public void CanExecuteDuringAsyncExecute2()
{
var tcs = new TaskCompletionSource<object>();
var canExecute = false;
var executeCalled = false;
var command = new AsyncDelegateCommand(() =>
{
executeCalled = true;
return tcs.Task;
}, () => canExecute);
Assert.IsFalse(command.CanExecute(null));
command.Execute(null);
Assert.IsFalse(executeCalled);
canExecute = true;
Assert.IsTrue(command.CanExecute(null));
command.Execute(null);
executeCalled = false;
Assert.IsFalse(command.CanExecute(null));
command.Execute(null);
Assert.IsFalse(executeCalled);
tcs.SetResult(null);
Assert.IsTrue(command.CanExecute(null));
command.Execute(null);
Assert.IsTrue(executeCalled);
}
public void CanExecuteDuringAsyncExecute()
{
AssertHelper.ExpectedException<ArgumentNullException>(() => new AsyncDelegateCommand((Func<Task>)null));
var tcs = new TaskCompletionSource<object>();
var executeCalled = false;
var command = new AsyncDelegateCommand(() =>
{
executeCalled = true;
return tcs.Task;
});
Assert.IsTrue(command.CanExecute(null));
command.Execute(null);
executeCalled = false;
Assert.IsFalse(command.CanExecute(null));
command.Execute(null);
Assert.IsFalse(executeCalled);
tcs.SetResult(null);
Assert.IsTrue(command.CanExecute(null));
command.Execute(null);
Assert.IsTrue(executeCalled);
}
public void CanExecuteDuringAsyncExecuteWithParameter()
{
var tcs = new TaskCompletionSource<object>();
string commandParameter = null;
var command = new AsyncDelegateCommand(p =>
{
commandParameter = (string)p;
return tcs.Task;
});
Assert.IsTrue(command.CanExecute(null));
command.Execute("test");
Assert.IsFalse(command.CanExecute(null));
tcs.SetResult(null);
Assert.IsTrue(command.CanExecute(null));
Assert.AreEqual("test", commandParameter);
}
public void RaiseCanExecuteChangedTest()
{
var executed = false;
var canExecute = false;
var command = new AsyncDelegateCommand(() => { executed = true; return Task.FromResult((object)null); }, () => canExecute);
Assert.IsFalse(command.CanExecute(null));
canExecute = true;
Assert.IsTrue(command.CanExecute(null));
AssertHelper.CanExecuteChangedEvent(command, () => command.RaiseCanExecuteChanged());
AssertHelper.CanExecuteChangedEvent(command, () => command.Execute(null), 2, ExpectedChangedCountMode.Exact); // Because during execution CanExecute returns false
Assert.IsTrue(executed);
}