Request data update before client response (#11341)

* Request data update before client response

* fix the accidental commit

* add tests

fixes #11320 

4 files changed, 107 insertions, 5 deletions

diff --git a/server/src/main/java/com/vaadin/data/provider/DataCommunicator.java b/server/src/main/java/com/vaadin/data/provider/DataCommunicator.java
index 449cbc5711..35dad20c49 100644
--- a/server/src/main/java/com/vaadin/data/provider/DataCommunicator.java
+++ b/server/src/main/java/com/vaadin/data/provider/DataCommunicator.java
@@ -530,6 +530,7 @@ public class DataCommunicator<T> extends AbstractExtension {
     public void reset() {
         // Only needed if a full reset is not pending.
         if (!reset) {
+            beforeClientResponse(true);
             // Soft reset through client-side re-request.
             getClientRpc().reset(getDataProviderSize());
         }
diff --git a/server/src/test/java/com/vaadin/data/provider/DataCommunicatorTest.java b/server/src/test/java/com/vaadin/data/provider/DataCommunicatorTest.java
index c187c91471..98ae758b6d 100644
--- a/server/src/test/java/com/vaadin/data/provider/DataCommunicatorTest.java
+++ b/server/src/test/java/com/vaadin/data/provider/DataCommunicatorTest.java
@@ -1,9 +1,5 @@
 package com.vaadin.data.provider;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertTrue;
-
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.concurrent.Future;
@@ -25,6 +21,9 @@ import com.vaadin.ui.UI;
 import elemental.json.Json;
 import elemental.json.JsonArray;
 import elemental.json.JsonObject;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
 
 /**
  * @author Vaadin Ltd
@@ -303,7 +302,7 @@ public class DataCommunicatorTest {
         // Mark communicator clean
         ui.getConnectorTracker().markClean(communicator);
 
-        assertTrue("Communicator should be marked for hard reset",
+        assertFalse("Communicator should not be marked for hard reset",
                 communicator.reset);
         assertFalse("DataCommunicator should not be marked as dirty",
                 ui.getConnectorTracker().isDirty(communicator));
diff --git a/uitest/src/main/java/com/vaadin/tests/components/combobox/ComboBoxItemSize.java b/uitest/src/main/java/com/vaadin/tests/components/combobox/ComboBoxItemSize.java
new file mode 100644
index 0000000000..ed30bac755
--- /dev/null
+++ b/uitest/src/main/java/com/vaadin/tests/components/combobox/ComboBoxItemSize.java
@@ -0,0 +1,51 @@
+package com.vaadin.tests.components.combobox;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Optional;
+
+import com.vaadin.annotations.Widgetset;
+import com.vaadin.data.provider.DataProvider;
+import com.vaadin.server.VaadinRequest;
+import com.vaadin.tests.components.AbstractTestUI;
+import com.vaadin.tests.widgetset.TestingWidgetSet;
+import com.vaadin.ui.Button;
+import com.vaadin.ui.ComboBox;
+import com.vaadin.ui.Label;
+
+@Widgetset(TestingWidgetSet.NAME)
+public class ComboBoxItemSize extends AbstractTestUI {
+    @Override
+    protected void setup(VaadinRequest request) {
+        List<String> items = new ArrayList<>(Arrays.asList("blue", "red",
+                "green", "purple", "grey", "orange"));
+
+        ComboBox<String> comboBox = new ComboBox<>();
+        comboBox.setId("combobox");
+        comboBox.setPageLength(0);
+        comboBox.setItems(items);
+        DataProvider<String, ?> dataProvider = comboBox.getDataProvider();
+        comboBox.setNewItemProvider(value -> {
+            items.add(value);
+            dataProvider.refreshAll();
+            return Optional.ofNullable(value);
+        });
+
+        Button button = new Button("get value");
+        Label label = new Label("value of combobox");
+        button.addClickListener(event -> label
+                .setValue("combobox value " + comboBox.getValue()));
+
+        Button reset = new Button("reset");
+        reset.addClickListener(event -> {
+            items.clear();
+            items.addAll(Arrays.asList("blue", "red", "green", "purple", "grey",
+                    "orange"));
+            dataProvider.refreshAll();
+            comboBox.setValue(null);
+        });
+
+        addComponents(comboBox, button, label, reset);
+    }
+}
diff --git a/uitest/src/test/java/com/vaadin/tests/components/combobox/ComboBoxItemSizeTest.java b/uitest/src/test/java/com/vaadin/tests/components/combobox/ComboBoxItemSizeTest.java
new file mode 100644
index 0000000000..cdb14ae420
--- /dev/null
+++ b/uitest/src/test/java/com/vaadin/tests/components/combobox/ComboBoxItemSizeTest.java
@@ -0,0 +1,51 @@
+package com.vaadin.tests.components.combobox;
+
+import org.junit.Test;
+import org.openqa.selenium.Keys;
+import org.openqa.selenium.interactions.Actions;
+
+import com.vaadin.testbench.By;
+import com.vaadin.testbench.elements.ComboBoxElement;
+import com.vaadin.tests.tb3.SingleBrowserTest;
+
+import static org.junit.Assert.assertEquals;
+
+public class ComboBoxItemSizeTest extends SingleBrowserTest {
+
+    ComboBoxElement comboBoxElement;
+
+    @Test
+    public void comboBoxItemSizeDisplayCorrectly() {
+
+        openTestURL();
+
+        comboBoxElement = $(ComboBoxElement.class).id("combobox");
+
+        // initial item size include the empty option
+        assertItemSizeInPopup(7);
+
+        comboBoxElement.clear();
+        sendKeysToInput("black");
+
+        assertItemSizeInPopup(8);
+
+    }
+
+    private void assertItemSizeInPopup(int expectedSize) {
+        comboBoxElement.findElement(By.className("v-filterselect-button"))
+                .click();
+        waitForElementPresent(By.className("v-filterselect-suggestpopup"));
+        int itemSize = findElement(By.className("v-filterselect-suggestmenu"))
+                .findElements(By.tagName("span")).size();
+        assertEquals("There should be " + expectedSize + "items in the popup.",
+                expectedSize, itemSize);
+    }
+
+    private void sendKeysToInput(CharSequence... keys) {
+        // ensure mouse is located over the ComboBox to avoid hover issues
+        new Actions(getDriver()).moveToElement(comboBoxElement).perform();
+        comboBoxElement.sendKeys(keys);
+        comboBoxElement.sendKeys(Keys.ENTER);
+        waitForElementNotPresent(By.className("v-filterselect-suggestpopup"));
+    }
+}