Avoid client side exception on DnD for empty table (#13655).

Change-Id: I71c18e87760ecbff34cfe215f56390fd75f3e55c

3 files changed, 131 insertions, 2 deletions

diff --git a/client/src/com/vaadin/client/ui/VScrollTable.java b/client/src/com/vaadin/client/ui/VScrollTable.java
index 6f575ca1c0..38f8ff8644 100644
--- a/client/src/com/vaadin/client/ui/VScrollTable.java
+++ b/client/src/com/vaadin/client/ui/VScrollTable.java
@@ -7101,7 +7101,11 @@ public class VScrollTable extends FlowPanel implements HasWidgets,
             dropDetails = new TableDDDetails();
             Element elementOver = drag.getElementOver();
 
-            VScrollTableRow row = Util.findWidget(elementOver, getRowClass());
+            Class<? extends Widget> clazz = getRowClass();
+            VScrollTableRow row = null;
+            if (clazz != null) {
+                row = Util.findWidget(elementOver, clazz);
+            }
             if (row != null) {
                 dropDetails.overkey = row.rowKey;
                 Element tr = row.getElement();
@@ -7127,7 +7131,12 @@ public class VScrollTable extends FlowPanel implements HasWidgets,
         private Class<? extends Widget> getRowClass() {
             // get the row type this way to make dd work in derived
             // implementations
-            return scrollBody.iterator().next().getClass();
+            Iterator<Widget> iterator = scrollBody.iterator();
+            if (iterator.hasNext()) {
+                return iterator.next().getClass();
+            } else {
+                return null;
+            }
         }
 
         @Override
diff --git a/uitest/src/com/vaadin/tests/components/table/DndEmptyTable.java b/uitest/src/com/vaadin/tests/components/table/DndEmptyTable.java
new file mode 100644
index 0000000000..baac7ce057
--- /dev/null
+++ b/uitest/src/com/vaadin/tests/components/table/DndEmptyTable.java
@@ -0,0 +1,71 @@
+/*
+ * Copyright 2000-2013 Vaadin Ltd.
+ * 
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License. You may obtain a copy of
+ * the License at
+ * 
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations under
+ * the License.
+ */
+package com.vaadin.tests.components.table;
+
+import com.vaadin.event.dd.DragAndDropEvent;
+import com.vaadin.event.dd.DropHandler;
+import com.vaadin.event.dd.acceptcriteria.AcceptAll;
+import com.vaadin.event.dd.acceptcriteria.AcceptCriterion;
+import com.vaadin.server.VaadinRequest;
+import com.vaadin.tests.components.AbstractTestUI;
+import com.vaadin.ui.DragAndDropWrapper;
+import com.vaadin.ui.DragAndDropWrapper.DragStartMode;
+import com.vaadin.ui.Label;
+import com.vaadin.ui.Table;
+
+/**
+ * Test UI for empty table: empty table (without any data) throws client side
+ * exception if it's a target for DnD.
+ * 
+ * @since
+ * @author Vaadin Ltd
+ */
+public class DndEmptyTable extends AbstractTestUI {
+
+    @Override
+    protected void setup(VaadinRequest request) {
+        Label source = new Label("label");
+        DragAndDropWrapper wrapper = new DragAndDropWrapper(source);
+        wrapper.setDragStartMode(DragStartMode.WRAPPER);
+        addComponent(wrapper);
+
+        Table target = new Table();
+        target.setWidth(100, Unit.PERCENTAGE);
+        addComponent(target);
+        target.setDropHandler(new DropHandler() {
+
+            @Override
+            public AcceptCriterion getAcceptCriterion() {
+                return AcceptAll.get();
+            }
+
+            @Override
+            public void drop(DragAndDropEvent event) {
+            }
+        });
+    }
+
+    @Override
+    protected String getTestDescription() {
+        return "Drag and drop into empty table should not throws client side exception.";
+    }
+
+    @Override
+    protected Integer getTicketNumber() {
+        return 13655;
+    }
+
+}
diff --git a/uitest/src/com/vaadin/tests/components/table/DndEmptyTableTest.java b/uitest/src/com/vaadin/tests/components/table/DndEmptyTableTest.java
new file mode 100644
index 0000000000..4c682637b1
--- /dev/null
+++ b/uitest/src/com/vaadin/tests/components/table/DndEmptyTableTest.java
@@ -0,0 +1,49 @@
+/*
+ * Copyright 2000-2013 Vaadin Ltd.
+ * 
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License. You may obtain a copy of
+ * the License at
+ * 
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * 
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations under
+ * the License.
+ */
+package com.vaadin.tests.components.table;
+
+import org.junit.Assert;
+import org.junit.Test;
+import org.openqa.selenium.WebElement;
+import org.openqa.selenium.interactions.Actions;
+
+import com.vaadin.testbench.By;
+import com.vaadin.tests.tb3.MultiBrowserTest;
+
+/**
+ * Test for empty table as a DnD target: it should not throws client side
+ * exception.
+ * 
+ * @since
+ * @author Vaadin Ltd
+ */
+public class DndEmptyTableTest extends MultiBrowserTest {
+
+    @Test
+    public void testDndEmptyTable() {
+        setDebug(true);
+        openTestURL();
+
+        WebElement source = driver.findElement(By.className("v-ddwrapper"));
+        WebElement target = driver.findElement(By.className("v-table-body"));
+        Actions actions = new Actions(driver);
+        actions.clickAndHold(source).moveToElement(target).release();
+
+        Assert.assertFalse(isElementPresent(By
+                .className("v-Notification-error")));
+    }
+
+}