Correctly reset DataCommunicator when its DataProvider is changed (#8138)

* Correctly reset DataCommunicator when its DataProvider is changed

* Improve ReplaceDataProviderTest

* Remove return type from AbstractListing.readItems

2 files changed, 120 insertions, 0 deletions

diff --git a/uitest/src/main/java/com/vaadin/tests/data/ReplaceDataProvider.java b/uitest/src/main/java/com/vaadin/tests/data/ReplaceDataProvider.java
new file mode 100644
index 0000000000..8a33cae95d
--- /dev/null
+++ b/uitest/src/main/java/com/vaadin/tests/data/ReplaceDataProvider.java
@@ -0,0 +1,67 @@
+package com.vaadin.tests.data;
+
+import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
+
+import com.vaadin.server.VaadinRequest;
+import com.vaadin.tests.components.AbstractTestUI;
+import com.vaadin.ui.Button;
+import com.vaadin.ui.Grid;
+
+public class ReplaceDataProvider extends AbstractTestUI {
+
+    private static class TestClass {
+        public String someField;
+        public int hash;
+
+        public TestClass(int hash) {
+            this.hash = hash;
+            someField = "a";
+        }
+
+        @Override
+        public int hashCode() {
+            return hash;
+        }
+
+        @Override
+        public boolean equals(Object obj) {
+            return true;
+        }
+    }
+
+    @Override
+    protected void setup(VaadinRequest request) {
+        Grid<TestClass> grid = new Grid<>();
+        grid.addColumn(item -> item.someField);
+
+        List<TestClass> listOfClasses = IntStream.range(0, 10)
+                .mapToObj(TestClass::new).collect(Collectors.toList());
+        for (int i = 0; i < 10; i++) {
+            listOfClasses.add(new TestClass(10));
+        }
+
+        grid.setItems(listOfClasses);
+
+        Button replaceBtn = new Button("replace data provider");
+        replaceBtn.addClickListener(clickEvent -> {
+            List<TestClass> newList = IntStream.range(0, 10)
+                    .mapToObj(TestClass::new).collect(Collectors.toList());
+            newList.get(0).someField = "b";
+            grid.setItems(newList);
+        });
+
+        Button replaceAndSelectBtn = new Button(
+                "replace data provider and select second");
+        replaceAndSelectBtn.addClickListener(clickEvent -> {
+            List<TestClass> newList = IntStream.range(0, 10)
+                    .mapToObj(TestClass::new).collect(Collectors.toList());
+            newList.get(0).someField = "b";
+            grid.setItems(newList);
+            grid.getSelectionModel().select(newList.get(1));
+        });
+
+        addComponents(replaceBtn, replaceAndSelectBtn, grid);
+    }
+}
diff --git a/uitest/src/test/java/com/vaadin/tests/data/ReplaceDataProviderTest.java b/uitest/src/test/java/com/vaadin/tests/data/ReplaceDataProviderTest.java
new file mode 100644
index 0000000000..7fa495cf24
--- /dev/null
+++ b/uitest/src/test/java/com/vaadin/tests/data/ReplaceDataProviderTest.java
@@ -0,0 +1,53 @@
+package com.vaadin.tests.data;
+
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+
+import com.vaadin.testbench.elements.ButtonElement;
+import com.vaadin.testbench.elements.GridElement;
+import com.vaadin.tests.tb3.SingleBrowserTest;
+
+public class ReplaceDataProviderTest extends SingleBrowserTest {
+
+    @Before
+    public void setUp() {
+        openTestURL();
+    }
+
+    @Test
+    public void test_grid_data_communication_with_replaced_data_provider() {
+        GridElement grid = $(GridElement.class).first();
+        ButtonElement replaceDataProviderButton = $(ButtonElement.class)
+                .first();
+
+        Assert.assertEquals(20, grid.getRowCount());
+        grid.getCell(0, 0).click();
+        assertCellText("a", 0, 0);
+
+        replaceDataProviderButton.click();
+
+        Assert.assertEquals(10, grid.getRowCount());
+        assertCellText("b", 0, 0);
+        for (int i = 1; i < 10; i++) {
+            assertCellText("a", i, 0);
+        }
+
+        Assert.assertFalse(grid.getRow(0).isSelected());
+
+        grid.getCell(0, 0).click();
+        assertCellText("b", 0, 0);
+
+        // This button should replace the data provider and do a server side
+        // select on the second item
+        $(ButtonElement.class).get(1).click();
+        grid.getRow(1).isSelected();
+    }
+
+    private void assertCellText(String text, int rowIndex, int colIndex) {
+        String firstCellText = $(GridElement.class).first()
+                .getCell(rowIndex, colIndex)
+                .getText();
+        Assert.assertEquals(text, firstCellText);
+    }
+}