How to correctly unit test call a user interface method in another thread?

Question

After coding the extension method (based on a GUI update when you run the event handler class in a separate thread? ):

public static class ControlExtensions
{
    public static TResult InvokeEx<TControl, TResult> (this TControl control,
                                                       Func<TControl, TResult> func)
      where TControl : Control
    {
        if (control.InvokeRequired)
            return (TResult)control.Invoke (func, control);

        return func (control);
    }
}

I am trying to use unit test this method both from the user interface thread and from the normal thread, and I cannot achieve this.

Here is the unit test code:

[Test]
public void TestInvokeExWithMethodReturningResultOnOtherThread ()
{
    // Prepare
    string result = string.Empty;
    var form = new Form ();
    var thread = new Thread (() =>
                             {
                                 result = form.InvokeEx (f => f.Text);
                             });

    // Execute
    thread.Start ();
    thread.Join (1000);

    // Verify
    Assert.That (result, Is.EqualTo ("Some label"));
}

The test passes, but if I set a breakpoint in the InvokeEx method (and not in the call), I see that Control.InvokeRequired is incorrect, which leads to functions .

In addition, now the test failed because the result is not set.

, , func ( ), .

, , , unit test? ?

Answer 1

, :

[Test]
public void TestInvokeExWithMethodReturningResultOnOtherThread ()
{
    // Prepare
    string result = string.Empty;
    var form = new Form ();
    var uiThread = new Thread (() => Application.Run (form));
    uiThread.SetApartmentState (ApartmentState.STA);
    uiThread.Start();
    Thread.Sleep (100);
    var thread = new Thread (() => result = form.InvokeEx (f => f.Text));

    // Execute
    thread.Start ();
    thread.Join ();
    form.InvokeEx (f => f.Close ());
    uiThread.Join ();

    // Verify
    Assert.That (result, Is.EqualTo ("Some label"));
}

.

, InvokeEx void.