Random StringIndexOutOfBoundsException when calling TitleAreaDialog.getMessage

[henryju]

Hi,

I have a test failing from time to time with this exception:

java.lang.StringIndexOutOfBoundsException: String index out of range: -1
	at java.base/java.lang.String.substring(String.java:1841)
	at org.eclipse.reddeer.jface.dialogs.TitleAreaDialog.getMessage(TitleAreaDialog.java:96)

I don't know how to reproduce.

We are waiting for an error message to be displayed in our Wizard:

// test code
 wizard.next();
 new WaitUntil(new DialogMessageIsExpected(wizard, "Authentication failed"));

// utility class
public class DialogMessageIsExpected extends AbstractWaitCondition {

  private final TitleAreaDialog dialog;
  private final String expectedMessage;

  public DialogMessageIsExpected(TitleAreaDialog dialog, String expectedMessage) {
    this.dialog = dialog;
    this.expectedMessage = expectedMessage;
  }

  @Override
  public boolean test() {
    return dialog.getMessage().equals(expectedMessage);
  }

}

The recording of the test shows that the message is present (but possibly the exception already occurred):

I guess it could be a race condition in TitleAreaDialog.getMessage:

public String getMessage() {
		checkShell();
		// Page Message is 5th Text within first Composite of TitleAreaDialog and is inactive 
		Control textControl = handler.getChildren(getShellComposite())[4];
		String message = "";
// -> At this moment the message and image are still empty
		if (textControl instanceof org.eclipse.swt.widgets.Label) {
			message = getMessageLabel(textControl).getText(); // message = ""
		} else {
			message = getMessageText(textControl).getText();
		}
// --> Here the message and image are changed to Error icon + "Authentication failed", but the message variable has already been assigned
		if(getMessageImage() != null){ // image is not null
			message = message.substring(1); // StringIndexOutOfBoundsException
		}
		return message;
	}

If I'm correct, a fix could be to add a guard before calling message.substring(1):

		if(getMessageImage() != null && message.length > 0){ //if image is shown TitleAreaDialog adds whitespace before message
			message = message.substring(1);
		}

Except if you can think of an atomic way of getting both the image and the message at the same time?