Display the caption of the Empty selection in NativeSelect (#11191)

* Fixes #10937

- Previously if selected value is null, then index is set to -1; in current implementation if value is null and emptySelection is allowed then set the index to 0. (The position for the empty selection)

- Also, if changing the allowEmptySelection on the fly, ensure, that either index is to-reset to -1 by setting the selected value to null on the client-side (the value before was null) or preserve the value(value was different than empty).

* Change the test case

Since in this pr the behaviour of the NS is changed, therefore old test need to be adjusted.

Change: setting null as value will select empty selection. Before that nothing would be selected and value will be cleared.

Behaviour change in PR: Allow selecting null as value

1 files changed, 59 insertions, 0 deletions

diff --git a/uitest/src/test/java/com/vaadin/tests/components/nativeselect/NativeSelectSetNullTest.java b/uitest/src/test/java/com/vaadin/tests/components/nativeselect/NativeSelectSetNullTest.java
new file mode 100644
index 0000000000..90afe9f463
--- /dev/null
+++ b/uitest/src/test/java/com/vaadin/tests/components/nativeselect/NativeSelectSetNullTest.java
@@ -0,0 +1,59 @@
+package com.vaadin.tests.components.nativeselect;
+
+import com.vaadin.testbench.elements.NativeSelectElement;
+import com.vaadin.tests.tb3.MultiBrowserTest;
+import org.junit.Before;
+import org.junit.Test;
+import org.openqa.selenium.By;
+import org.openqa.selenium.WebElement;
+
+import static junit.framework.TestCase.assertEquals;
+
+public class NativeSelectSetNullTest extends MultiBrowserTest {
+
+    @Before
+    public void setUp() {
+        openTestURL();
+    }
+
+    @Test
+    public void testCaptionSelected() {
+        getButtonOnId("setNull");
+        assertEquals(NativeSelectSetNull.EMPTY_SELECTION_TEXT,
+                getSelect().getValue());
+    }
+
+    @Test
+    public void changeSelectedValue() {
+        getButtonOnId("changeSelect").click();
+        assertEquals(3, Integer.valueOf(getSelect().getValue()).intValue());
+    }
+
+    @Test
+    public void clearSelection() {
+        getButtonOnId("clear").click();
+        assertEquals(NativeSelectSetNull.EMPTY_SELECTION_TEXT,
+                getSelect().getValue());
+    }
+
+    @Test
+    public void valuePreservedAfterAllowEmptySelectionChanged() {
+        getSelect().setValue("2");
+        getButtonOnId("disable").click();
+        assertEquals(2, Integer.valueOf(getSelect().getValue()).intValue());
+
+        getButtonOnId("disable").click();
+        getButtonOnId("setNull").click();
+        assertEquals(NativeSelectSetNull.EMPTY_SELECTION_TEXT,
+                getSelect().getValue());
+
+    }
+
+    protected NativeSelectElement getSelect() {
+        return $(NativeSelectElement.class).first();
+    }
+
+    protected WebElement getButtonOnId(String id) {
+        return findElement(By.id(id));
+    }
+}