Fix compatibility ComboBox filtering when page length is zero. (#12016)

Issue #11246, slightly modified cherry-pick from #11247

compatibility-server/src/main/java/com/vaadin/v7/ui/ComboBox.java

@@ -620,7 +620,9 @@ public class ComboBox extends AbstractSelect
         // page length usable for non-null items
         int effectivePageLength = pageLength
                 - (needNullSelectOption && (currentPage == 0) ? 1 : 0);
-        return Math.min(size - 1, first + effectivePageLength - 1);
+        // zero pageLength implies infinite page size
+        return pageLength == 0 ? size - 1
+                : Math.min(size - 1, first + effectivePageLength - 1);
     }
 
     /**

uitest/src/main/java/com/vaadin/v7/tests/components/combobox/ComboboxPageLengthZeroFilter.java

@@ -0,0 +1,89 @@
+/*
+* Copyright 2000-2020 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.v7.tests.components.combobox;
+
+import com.vaadin.server.VaadinRequest;
+import com.vaadin.tests.components.AbstractTestUI;
+import com.vaadin.v7.data.util.BeanContainer;
+import com.vaadin.v7.ui.AbstractSelect.ItemCaptionMode;
+import com.vaadin.v7.ui.ComboBox;
+
+/**
+ * Test for issue #11246 where ComboBox set to render from Property does not
+ * filter correctly when page size is 0
+ *
+ * @author Vaadin Ltd
+ */
+@SuppressWarnings("deprecation")
+public class ComboboxPageLengthZeroFilter extends AbstractTestUI {
+
+    public static class Topping {
+        private int id;
+        private String name;
+
+        public Topping(int id, String name) {
+            this.id = id;
+            this.name = name;
+        }
+
+        public void setId(int id) {
+            this.id = id;
+        }
+
+        public int getId() {
+            return id;
+        }
+
+        public void setName(String name) {
+            this.name = name;
+        }
+
+        public String getName() {
+            return name;
+        }
+    }
+
+    @Override
+    protected void setup(VaadinRequest request) {
+        BeanContainer<Integer, Topping> container = new BeanContainer<Integer, Topping>(
+                Topping.class);
+        container.setBeanIdProperty("id");
+        for (int i = 0; i < 12; i++) {
+            container.addBean(new Topping(i, "Topping " + i));
+        }
+
+        final ComboBox comboBox = new ComboBox();
+        comboBox.setPageLength(0);
+        comboBox.setItemCaptionMode(ItemCaptionMode.PROPERTY);
+        comboBox.setItemCaptionPropertyId("name");
+        comboBox.setContainerDataSource(container);
+        comboBox.setInvalidAllowed(false);
+        comboBox.setNullSelectionAllowed(false);
+        comboBox.setTextInputAllowed(true);
+
+        getLayout().addComponent(comboBox);
+    }
+
+    @Override
+    protected Integer getTicketNumber() {
+        return 11246;
+    }
+
+    @Override
+    protected String getTestDescription() {
+        return "Filtering should work even when ComboBox page length is zero.";
+    }
+}

uitest/src/test/java/com/vaadin/v7/tests/components/combobox/ComboboxPageLengthZeroFilterTest.java

@@ -0,0 +1,28 @@
+package com.vaadin.v7.tests.components.combobox;
+import java.util.List;
+
+import org.junit.Assert;
+import org.junit.Test;
+
+import com.vaadin.testbench.By;
+import com.vaadin.testbench.elements.ComboBoxElement;
+import com.vaadin.tests.tb3.MultiBrowserTest;
+
+public class ComboboxPageLengthZeroFilterTest extends MultiBrowserTest {
+
+    @Test
+    public void testOptionsNotEmpty() {
+        openTestURL();
+
+        List<String> suggestions = getFilterSuggestions("T");
+
+        Assert.assertEquals("All items should be presented!", 12,
+                suggestions.size());
+    }
+
+    private List<String> getFilterSuggestions(String string) {
+        ComboBoxElement comboBox = $(ComboBoxElement.class).first();
+        comboBox.findElement(By.vaadin("#textbox")).sendKeys(string);
+        return comboBox.getPopupSuggestions();
+    }
+}