Introduce instruction::Target in test crate

core/src/widget/operation/text_input.rs

@@ -5,12 +5,20 @@ use crate::widget::operation::Operation;
 
 /// The internal state of a widget that has text input.
 pub trait TextInput {
+    /// Returns the current _visible_ text of the text input
+    ///
+    /// Normally, this is either its value or its placeholder.
+    fn text(&self) -> &str;
+
     /// Moves the cursor of the text input to the front of the input text.
     fn move_cursor_to_front(&mut self);
+
     /// Moves the cursor of the text input to the end of the input text.
     fn move_cursor_to_end(&mut self);
+
     /// Moves the cursor of the text input to an arbitrary location.
     fn move_cursor_to(&mut self, position: usize);
+
     /// Selects all the content of the text input.
     fn select_all(&mut self);
 }