WW-5331 Covers new logic with tests

core/src/main/java/org/apache/struts2/dispatcher/RequestMap.java

@@ -94,6 +94,7 @@ public class RequestMap extends AbstractMap<String, Object> implements Serializa
      * @param key the name of the request attribute.
      * @return the request attribute or <tt>null</tt> if it doesn't exist.
      */
+    @Override
     public Object get(final Object key) {
         if (key == null) {
             return null;

core/src/test/java/org/apache/struts2/dispatcher/RequestMapTest.java

@@ -0,0 +1,75 @@
+package org.apache.struts2.dispatcher;
+
+import org.junit.Test;
+import org.springframework.mock.web.MockHttpServletRequest;
+
+import javax.servlet.http.HttpServletRequest;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNull;
+
+public class RequestMapTest {
+
+    @Test
+    public void shouldAccessRequestAttributes() {
+        // given
+        HttpServletRequest request = new MockHttpServletRequest();
+        request.setAttribute("attr", "value");
+
+        // when
+        RequestMap rm = new RequestMap(request);
+        Object value = rm.get("attr");
+
+        // then
+        assertEquals("value", value);
+    }
+
+    @Test
+    public void shouldReturnNullIfKeyIsNull() {
+        // given
+        HttpServletRequest request = new MockHttpServletRequest();
+
+        // when
+        RequestMap rm = new RequestMap(request);
+        Object value = rm.get(null);
+
+        // then
+        assertNull(value);
+    }
+
+    @Test
+    public void shouldRemoveAttributeFromRequest() {
+        // given
+        HttpServletRequest request = new MockHttpServletRequest();
+        request.setAttribute("attr", "value");
+
+        // when
+        RequestMap rm = new RequestMap(request);
+        Object value = rm.remove("attr");
+
+        // then
+        assertEquals("value", value);
+        assertNull(request.getAttribute("attr"));
+    }
+
+    @Test
+    public void shouldClearAttributes() {
+        // given
+        HttpServletRequest request = new MockHttpServletRequest();
+        request.setAttribute("attr", "value");
+
+        // when
+        RequestMap rm = new RequestMap(request);
+        Object value = rm.get("attr");
+
+        // then
+        assertEquals("value", value);
+
+        // when
+        rm.clear();
+
+        // then
+        assertNull(request.getAttribute("attr"));
+    }
+
+}