feat: add keepFilter option

vaadin-combo-box-flow-parent/vaadin-combo-box-flow-integration-tests/src/main/java/com/vaadin/flow/component/combobox/test/MultiSelectComboBoxKeepFilterPage.java

@@ -0,0 +1,29 @@
+package com.vaadin.flow.component.combobox.test;
+
+import com.vaadin.flow.component.checkbox.Checkbox;
+import com.vaadin.flow.component.combobox.MultiSelectComboBox;
+import com.vaadin.flow.component.html.Div;
+import com.vaadin.flow.router.Route;
+
+import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.IntStream;
+
+@Route("vaadin-multi-select-combo-box/keep-filter")
+public class MultiSelectComboBoxKeepFilterPage extends Div {
+    public MultiSelectComboBoxKeepFilterPage() {
+        MultiSelectComboBox<String> comboBox = new MultiSelectComboBox<>(
+                "Items");
+        List<String> items = IntStream.range(0, 100)
+                .mapToObj(i -> "Item " + (i + 1)).collect(Collectors.toList());
+        comboBox.setItems(items);
+
+        Checkbox keepFilter = new Checkbox("Keep filter");
+        keepFilter.setId("keep-filter");
+        keepFilter.addValueChangeListener(e -> {
+            comboBox.setKeepFilter(keepFilter.getValue());
+        });
+
+        add(comboBox, keepFilter);
+    }
+}

vaadin-combo-box-flow-parent/vaadin-combo-box-flow-integration-tests/src/test/java/com/vaadin/flow/component/combobox/test/MultiSelectComboBoxKeepFilterIT.java

@@ -0,0 +1,55 @@
+package com.vaadin.flow.component.combobox.test;
+
+import com.vaadin.flow.component.combobox.testbench.MultiSelectComboBoxElement;
+import com.vaadin.flow.testutil.TestPath;
+import com.vaadin.testbench.TestBenchElement;
+import com.vaadin.tests.AbstractComponentIT;
+import org.junit.Assert;
+import org.junit.Before;
+import org.junit.Test;
+import org.openqa.selenium.Keys;
+
+import java.util.List;
+
+@TestPath("vaadin-multi-select-combo-box/keep-filter")
+public class MultiSelectComboBoxKeepFilterIT extends AbstractComponentIT {
+    private MultiSelectComboBoxElement comboBox;
+    private TestBenchElement keepFilter;
+
+    @Before
+    public void init() {
+        open();
+        comboBox = $(MultiSelectComboBoxElement.class).waitForFirst();
+        keepFilter = $(TestBenchElement.class).id("keep-filter");
+    }
+
+    @Test
+    public void keepFilterDisabled_clearsFilterAfterSelection() {
+        comboBox.sendKeys("Item 1");
+        comboBox.waitForLoadingFinished();
+        List<String> filteredOptions = comboBox.getOptions();
+        Assert.assertEquals(12, filteredOptions.size());
+
+        comboBox.sendKeys(Keys.ENTER);
+
+        Assert.assertEquals("", comboBox.getInputElementValue());
+        Assert.assertEquals("", comboBox.getFilter());
+        Assert.assertEquals(100, comboBox.getOptions().size());
+    }
+
+    @Test
+    public void keepFilterEnabled_keepsFilterAfterSelection() {
+        keepFilter.click();
+
+        comboBox.sendKeys("Item 1");
+        comboBox.waitForLoadingFinished();
+        List<String> filteredOptions = comboBox.getOptions();
+        Assert.assertEquals(12, filteredOptions.size());
+
+        comboBox.sendKeys(Keys.ENTER);
+
+        Assert.assertEquals("Item 1", comboBox.getInputElementValue());
+        Assert.assertEquals("Item 1", comboBox.getFilter());
+        Assert.assertEquals(filteredOptions, comboBox.getOptions());
+    }
+}

vaadin-combo-box-flow-parent/vaadin-combo-box-flow/src/main/java/com/vaadin/flow/component/combobox/MultiSelectComboBox.java

@@ -506,6 +506,30 @@ public void setSelectedItemsOnTop(boolean selectedItemsOnTop) {
         getElement().setProperty("selectedItemsOnTop", selectedItemsOnTop);
     }
 
+    /**
+     * Gets whether the filter is kept after selecting items. {@code false} by
+     * default.
+     *
+     * @since 24.4
+     * @return {@code true} if enabled, {@code false} otherwise
+     */
+    public boolean isKeepFilter() {
+        return getElement().getProperty("keepFilter", false);
+    }
+
+    /**
+     * Enables or disables keeping the filter after selecting items. By default,
+     * the filter is cleared after selecting an item and the overlay shows the
+     * unfiltered list of items again. Enabling this option will keep the
+     * filter, which allows to select multiple filtered items in succession.
+     *
+     * @param keepFilter
+     *            whether to keep the filter after selecting an item
+     */
+    public void setKeepFilter(boolean keepFilter) {
+        getElement().setProperty("keepFilter", keepFilter);
+    }
+
     /**
      * Gets the internationalization object previously set for this component.
      * <p>

vaadin-combo-box-flow-parent/vaadin-combo-box-flow/src/test/java/com/vaadin/flow/component/combobox/MultiSelectComboBoxTest.java

@@ -321,4 +321,19 @@ public void setSelectedItemsOnTop() {
         Assert.assertTrue(
                 comboBox.getElement().getProperty("selectedItemsOnTop", true));
     }
+
+    @Test
+    public void setKeepFilter() {
+        MultiSelectComboBox<String> comboBox = new MultiSelectComboBox<>();
+
+        Assert.assertFalse(comboBox.isKeepFilter());
+        Assert.assertFalse(
+                comboBox.getElement().getProperty("keepFilter", false));
+
+        comboBox.setKeepFilter(true);
+
+        Assert.assertTrue(comboBox.isKeepFilter());
+        Assert.assertTrue(
+                comboBox.getElement().getProperty("keepFilter", true));
+    }
 }