Always return cursor position 0 when displaying input prompt (#19766)

Change-Id: Ibca58259a0bbcda7141b996020bae8614f0c2114

client/src/main/java/com/vaadin/client/ui/VTextField.java

@@ -423,7 +423,7 @@ public class VTextField extends TextBoxBase implements Field, ChangeHandler,
      */
     protected boolean updateCursorPosition() {
         if (WidgetUtil.isAttachedAndDisplayed(this)) {
-            int cursorPos = getCursorPos();
+            int cursorPos = prompting ? 0 : getCursorPos();
             if (lastCursorPos != cursorPos) {
                 client.updateVariable(paintableId,
                         TextFieldConstants.VAR_CURSOR, cursorPos, false);

uitest/src/main/java/com/vaadin/tests/components/textfield/InputPromptAndCursorPosition.java

@@ -0,0 +1,42 @@
+package com.vaadin.tests.components.textfield;
+
+import com.vaadin.server.VaadinRequest;
+import com.vaadin.tests.components.AbstractTestUI;
+import com.vaadin.ui.Button;
+import com.vaadin.ui.Button.ClickEvent;
+import com.vaadin.ui.Label;
+import com.vaadin.ui.TextField;
+
+public class InputPromptAndCursorPosition extends AbstractTestUI {
+
+    @Override
+    protected void setup(VaadinRequest request) {
+        final TextField tf = new TextField();
+        tf.setColumns(40);
+        tf.setValue("Delete this text to reveal input prompt and update cursor position.");
+        tf.setInputPrompt("This is an input prompt");
+
+        final Label l = new Label("Cursor position: ?");
+        Button button = new Button("Update cursor position", new Button.ClickListener() {
+
+            @Override
+            public void buttonClick(ClickEvent event) {
+                l.setValue("Cursor position: " + tf.getCursorPosition());
+            }
+        });
+
+        addComponent(tf);
+        addComponent(l);
+        addComponent(button);
+    }
+
+    @Override
+    protected String getTestDescription() {
+        return "Cursor position should always be zero when input prompt is displayed.";
+    }
+
+    @Override
+    protected Integer getTicketNumber() {
+        return 19766;
+    }
+}

uitest/src/test/java/com/vaadin/tests/components/textfield/InputPromptAndCursorPositionTest.java

@@ -0,0 +1,30 @@
+package com.vaadin.tests.components.textfield;
+
+import static org.junit.Assert.assertEquals;
+
+import org.junit.Test;
+
+import com.vaadin.testbench.elements.ButtonElement;
+import com.vaadin.testbench.elements.LabelElement;
+import com.vaadin.testbench.elements.TextFieldElement;
+import com.vaadin.tests.tb3.MultiBrowserTest;
+
+public class InputPromptAndCursorPositionTest extends MultiBrowserTest {
+
+    @Test
+    public void verifyDatePattern() {
+        openTestURL();
+
+        // Clear the current value and reveal the input prompt.
+        TextFieldElement textFieldElement = $(TextFieldElement.class).get(0);
+        textFieldElement.setValue("");
+
+        // Update cursor position.
+        $(ButtonElement.class).get(0).click();
+
+        // The cursor position should now be zero (not the input prompt length).
+        LabelElement cursorPosLabel = $(LabelElement.class).get(1);
+        assertEquals(cursorPosLabel.getText(), "Cursor position: 0");
+    }
+
+}