Improve role usage in grid (#10206)

* add role="row" and role="gridcell"

* optimize code and add additional rows for the header

* add simple test

* improve code and add rowgroup

* add debug log

* add more log to test

* remove debug test info and add role before appending to tr

* wording - change contains to contain

* create enum for magic strings, change comments and method signature

* rename enum to be singular and rename param roleName to role

* update javadoc, rename and make enum public

client/src/main/java/com/vaadin/client/widgets/Escalator.java

@@ -1131,7 +1131,8 @@ public class Escalator extends Widget
      * The following WAI-ARIA attributes are added through this class:
      *
      * <ul>
-     * <li>aria-rowcount (since 8.2)</li>
+     *     <li>aria-rowcount (since 8.2)</li>
+     *     <li>roles provided by {@link AriaGridRole} (since 8.2)</li>
      * </ul>
      *
      * @since 8.2
@@ -1189,6 +1190,48 @@ public class Escalator extends Widget
 
             getTable().setAttribute("aria-rowcount", String.valueOf(allRows));
         }
+
+        /**
+         * Sets the {@code role} attribute to the given element.
+         *
+         * @param element     element that should get the role attribute
+         * @param role        role to be added
+         *
+         * @since
+         */
+        public void updateRole(final Element element, AriaGridRole role) {
+            element.setAttribute("role", role.getName());
+        }
+    }
+
+    /**
+     * Holds the currently used aria roles within the grid for rows and cells.
+     *
+     * @since
+     */
+    public enum AriaGridRole {
+
+        ROW("row"),
+        ROWHEADER("rowheader"),
+        ROWGROUP("rowgroup"),
+        GRIDCELL("gridcell"),
+        COLUMNHEADER("columnheader");
+
+        private final String name;
+
+
+        AriaGridRole(String name) {
+            this.name = name;
+        }
+
+        /**
+         * Return the name of the {@link AriaGridRole}.
+         *
+         * @return String name to be used as role attribute
+         */
+        public String getName() {
+            return name;
+        }
     }
 
     public abstract class AbstractRowContainer implements RowContainer {
@@ -1218,6 +1261,7 @@ public class Escalator extends Widget
         public AbstractRowContainer(
                 final TableSectionElement rowContainerElement) {
             root = rowContainerElement;
+            ariaGridHelper.updateRole(root, AriaGridRole.ROWGROUP);
         }
 
         @Override
@@ -1238,6 +1282,34 @@ public class Escalator extends Widget
          */
         protected abstract String getCellElementTagName();
 
+        /**
+         * Gets the role attribute of an element to represent a cell in a row.
+         * <p>
+         * Usually {@link AriaGridRole#GRIDCELL} except for a cell in
+         * the header.
+         *
+         * @return the role attribute for the element to represent cells
+         *
+         * @since
+         */
+        protected AriaGridRole getCellElementRole() {
+            return AriaGridRole.GRIDCELL;
+        }
+
+        /**
+         * Gets the role attribute of an element to represent a row in a grid.
+         * <p>
+         * Usually {@link AriaGridRole#ROW} except for a row in
+         * the header.
+         *
+         * @return the role attribute for the element to represent rows
+         *
+         * @since
+         */
+        protected AriaGridRole getRowElementRole() {
+            return AriaGridRole.ROW;
+        }
+
         @Override
         public EscalatorUpdater getEscalatorUpdater() {
             return updater;
@@ -1476,15 +1548,14 @@ public class Escalator extends Widget
                 final TableRowElement tr = TableRowElement.as(DOM.createTR());
                 addedRows.add(tr);
                 tr.addClassName(getStylePrimaryName() + "-row");
+                ariaGridHelper.updateRole(tr, getRowElementRole());
 
                 for (int col = 0; col < columnConfiguration
                         .getColumnCount(); col++) {
                     final double colWidth = columnConfiguration
                             .getColumnWidthActual(col);
-                    final TableCellElement cellElem = createCellElement(
-                            colWidth);
+                    final TableCellElement cellElem = createCellElement(colWidth);
                     tr.appendChild(cellElem);
-
                     // Set stylename and position if new cell is frozen
                     if (col < columnConfiguration.frozenColumns) {
                         cellElem.addClassName("frozen");
@@ -1632,6 +1703,7 @@ public class Escalator extends Widget
                 cellElem.getStyle().setWidth(width, Unit.PX);
             }
             cellElem.addClassName(getStylePrimaryName() + "-cell");
+            ariaGridHelper.updateRole(cellElem, getCellElementRole());
             return cellElem;
         }
 
@@ -2416,6 +2488,16 @@ public class Escalator extends Widget
             return "th";
         }
 
+        @Override
+        protected AriaGridRole getRowElementRole() {
+            return AriaGridRole.ROWHEADER;
+        }
+
+        @Override
+        protected AriaGridRole getCellElementRole() {
+            return AriaGridRole.COLUMNHEADER;
+        }
+
         @Override
         public void setStylePrimaryName(String primaryStyleName) {
             super.setStylePrimaryName(primaryStyleName);

uitest/src/test/java/com/vaadin/tests/components/grid/GridAriaRowcountTest.java

@@ -18,9 +18,9 @@ package com.vaadin.tests.components.grid;
 import com.vaadin.testbench.elements.ButtonElement;
 import com.vaadin.testbench.elements.GridElement;
 import com.vaadin.tests.tb3.SingleBrowserTest;
-import org.junit.Assert;
 import org.junit.Test;
 
+import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
 
 /**
@@ -36,6 +36,14 @@ public class GridAriaRowcountTest extends SingleBrowserTest {
 
         grid = $(GridElement.class).first();
 
+        // default grid should contain at least one of each role
+        String gridHtml = grid.getHTML();
+        assertTrue("Grid should contain a role=\"rowheader\"", gridHtml.contains("role=\"rowheader\""));
+        assertTrue("Grid should contain a role=\"columnheader\"", gridHtml.contains("role=\"columnheader\""));
+        assertTrue("Grid should contain a role=\"row\"", gridHtml.contains("role=\"row\""));
+        assertTrue("Grid should contain a role=\"gridcell\"", gridHtml.contains("role=\"gridcell\""));
+        assertTrue("Grid should contain a role=\"rowgroup\"", gridHtml.contains("role=\"rowgroup\""));
+
         // default with 1 header row and 2 body rows.
         assertTrue("Grid should have 3 rows", containsRows(3));