Why is a TextEditChange() in bUnit suddenly not working

Question

This was working and now does not. This is for a pretty simple page. I use DevExpress and emailTextBox is a DxTextBox.

This is successful

var emailTextBox = allTextBoxes.Single(x => x.Instance.InputId == "email");

emailTextBox.TextEditChange("");
button.Click();
var li = renderedComponent.Find("li.validation-message");
Assert.NotNull(li);
Assert.Equal("Your Email is required", li.InnerHtml);
Assert.Equal("", pageModel.Email);

Then this code immediately follows - and fails.

emailTextBox.TextEditChange("bogus");
button.Click();
li = renderedComponent.Find("li.validation-message");
Assert.NotNull(li);
Assert.Equal("The Email field is not a valid e-mail address.", li.InnerHtml);
Assert.Equal("bogus", pageModel.Email);

The problems are:

1. The error message it finds is the message for an empty field.
2. pageModel.Email is "".
3. In the debugger I look at emailTextBox.Text and it is "".

Is TextEditChange() not the right way to set the value in DxTextBox?

Update:

And sometimes randomly the above 2nd test passes, but then the next test, which is similar, fails. These tests assume that not only the <input> value is being set, but that the <DataAnnotationsValidator/> and <ValidationSummary/> have then run.

Update 2:

The following works:

emailTextBox.TextEditChange("bogus");
button.Click();
renderedComponent.Render();
li = renderedComponent.Find("li.validation-message");
Assert.NotNull(li);
Assert.Equal("The Email field is not a valid e-mail address.", li.InnerHtml);
Assert.Equal("bogus", pageModel.Email);

Is it required to call renderedComponent.Render() after the TextEditChange/Click?

Answer 1

I got a lot of help from the bUnit team on this and the fundamental answer is twofold.

First, I need to make each TextEditChange() & Click() test a separate unit test. Doing several in a row is asking for trouble because the page elements all stay the same and it's just the text that changes.

Second, do a WaitFor, usually on the renderedComponent.Find() with a timeout. The unit test thereby tests for the expected change not by asserting the value, but by throwing an exception if the expected change does not get rendered before the timeout.

emailTextBox.TextEditChange("bogus");
button.Click();
var li = renderedComponent.WaitForElement("li.validation-message", Timeout);
Assert.NotNull(li);