C# Shall I make my windows form event related private functions public just for testing purpose?

This might be a very generic question about how to do the unit test for windows form application and with async functions.

I am writing the unit test case for a windows form application which has the async function everywhere.

I have all the event handler functions, for example, button click event function, private. I need to test these functions but I cannot call these functions directly outside to test them.

I tried to fire the event function from the unit test code via calling PerformClick(). It works fine with generic function but does not work properly with async function as I think PeformClick() doesn't await and I cannot verify the result in the testing code.

Here is a simple example of my code. We have two-layout structures. Form class to have only the form design. Form presenter to hold all the logic of functions. I need to test the BtnApplyChangeClick function in the presenter class.

public interface IStandForm
{
    Control.ControllCollections controls {get;}
}
public partial class Form1 : Form, IStandardForm
{
   public Form1()
   {
        InitializeComponent(); // It has a button called BtnDelete
   }
   public Control.ControlCollection controls
   {
        return this.Controls;
   }
}

public class FormPresenter
{   
    IStandardForm myForm;
    IDBController dbController;
    public FormPresenter(IStandardForm form, IDBController dbController)
    {
       this.myForm = form;
       this.dbController = dbController;

       //Assign the event to the button
       Button BtnDelete= (Button)myForm.Controls["BtnDelete"];
       BtnDelete.Click += new System.EventHandler(BtnDeleteClick);
    }

    private async void BtnDeleteClick(object sender, EventArgs e)
    {
        //some validation code   

       //Call db delete
        await dbController.Delete();  
    }
}

//Test Code
[TestFixture]
public class TestFormLogin
{
    [Test]
    public async Task Delete_With_Exception()
    {            
        Mock<IDbController> mockDbController = new Mock<IDbController>();
        mockDbController.Setup(c => c.Delete()).ThrowAsync<Exception>(new Exception("Test Exception"));
        IStandardForm myForm = new Form1;

        FormPresenter = new FormPresenter(mockDbController.Object, myForm);
        Button BtnDelete=(Button)myForm.Controls["BtnDelete"];

        Action act = () => BtnDelete.PerformClick();

        //This assertion will be failed as PeformClick won't wait
        act.Should().Throw<Exception>();  
    }
}

The last line Exception assertion won't work. If I could call event handler function BtnDeleteClick the assertion will be fine.

Would that be a bad idea to just simply make the private event handler function to be public just for testing purpose? It will make my life easier but doesn't sound make sense.