diff --git a/auth/util/pom.xml b/auth/util/pom.xml
index b2cfc83ccf0..d6039f2ae9e 100644
--- a/auth/util/pom.xml
+++ b/auth/util/pom.xml
@@ -39,7 +39,7 @@
         <dependency>
             <groupId>org.wildfly.security</groupId>
             <artifactId>wildfly-elytron-auth</artifactId>
-        </dependency>    
+        </dependency>
         <dependency>
             <groupId>org.wildfly.security</groupId>
             <artifactId>wildfly-elytron-base</artifactId>
@@ -47,7 +47,7 @@
         <dependency>
             <groupId>org.wildfly.security</groupId>
             <artifactId>wildfly-elytron-credential</artifactId>
-        </dependency>        
+        </dependency>
         <dependency>
             <groupId>org.wildfly.security</groupId>
             <artifactId>wildfly-elytron-auth-server</artifactId>
@@ -60,17 +60,17 @@
             <groupId>org.wildfly.security</groupId>
             <artifactId>wildfly-elytron-security-manager-action</artifactId>
         </dependency>
-        
+
         <dependency>
             <groupId>org.wildfly.common</groupId>
             <artifactId>wildfly-common</artifactId>
             <!-- scope is compile ELY-1153 -->
         </dependency>
-        
+
         <dependency>
             <groupId>org.jboss.logging</groupId>
             <artifactId>jboss-logging</artifactId>
-        </dependency>        
+        </dependency>
         <dependency>
             <groupId>org.jboss.logging</groupId>
             <artifactId>jboss-logging-annotations</artifactId>
@@ -86,6 +86,17 @@
             <artifactId>sshd-common</artifactId>
         </dependency>
 
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.jmockit</groupId>
+            <artifactId>jmockit</artifactId>
+            <scope>test</scope>
+        </dependency>
+
     </dependencies>
 
-</project>
+</project>
\ No newline at end of file
diff --git a/auth/util/src/main/java/org/wildfly/security/auth/util/MappedRegexRealmMapper.java b/auth/util/src/main/java/org/wildfly/security/auth/util/MappedRegexRealmMapper.java
index baaba86721c..078d881cb6c 100644
--- a/auth/util/src/main/java/org/wildfly/security/auth/util/MappedRegexRealmMapper.java
+++ b/auth/util/src/main/java/org/wildfly/security/auth/util/MappedRegexRealmMapper.java
@@ -26,8 +26,8 @@
 import org.wildfly.security.evidence.Evidence;
 
 /**
- * A simple mapping regular expression-based realm mapper.  The pattern is used to find the realm portion
- * of the user name.  Then, a map is consulted to map this realm portion to an actual configured realm name.
+ * A simple mapping regular expression-based realm mapper. The pattern is used to find the realm portion
+ * of the user name. Then, a map is consulted to map this realm portion to an actual configured realm name.
  *
  * @author <a href="mailto:david.lloyd@redhat.com">David M. Lloyd</a>
  */
diff --git a/auth/util/src/test/java/org/wildfly/security/auth/util/MappedRegexRealmMapperTest.java b/auth/util/src/test/java/org/wildfly/security/auth/util/MappedRegexRealmMapperTest.java
new file mode 100644
index 00000000000..63c052bc119
--- /dev/null
+++ b/auth/util/src/test/java/org/wildfly/security/auth/util/MappedRegexRealmMapperTest.java
@@ -0,0 +1,63 @@
+/*
+ * JBoss, Home of Professional Open Source.
+ * Copyright 2016 Red Hat, Inc., and individual contributors
+ * as indicated by the @author tags.
+ *
+ * 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 org.wildfly.security.auth.util;
+
+import java.security.Principal;
+import java.util.Collections;
+import java.util.Map;
+import java.util.regex.Pattern;
+
+import org.junit.Assert;
+import org.junit.Test;
+import org.wildfly.security.auth.principal.NamePrincipal;
+import org.wildfly.security.x500.X500PrincipalBuilder;
+
+/**
+ * @author <a href="mailto:pesilva@redhat.com">Pedro Silva</a>
+ */
+public class MappedRegexRealmMapperTest {
+
+    @Test
+    public void shouldReturnNullForNonNamePrincipalInstance() {
+        Map<String, String> realmNameMap = Collections.emptyMap();
+        Pattern pattern = Pattern.compile("([A-Z]-\\d{4})");
+        MappedRegexRealmMapper mappedRegexRealmMapper = new MappedRegexRealmMapper(pattern, realmNameMap);
+        Principal principal = new X500PrincipalBuilder().build();
+        Assert.assertNull(mappedRegexRealmMapper.getRealmMapping(principal, null));
+    }
+
+    @Test
+    public void shouldReturnNullCantFindValueInMap() {
+        Map<String, String> realmNameMap = Collections.singletonMap("A-0000", "new_realm");
+        Pattern pattern = Pattern.compile("([A-Z]-\\d{4})");
+        MappedRegexRealmMapper mappedRegexRealmMapper = new MappedRegexRealmMapper(pattern, realmNameMap);
+        Principal principal = new NamePrincipal("A-9999");
+        Assert.assertNull(mappedRegexRealmMapper.getRealmMapping(principal, null));
+    }
+
+    @Test
+    public void shouldReturnSpecificRealmMapping() {
+        String realmName = "new_realm";
+        Map<String, String> realmNameMap = Collections.singletonMap("A-9999", realmName);
+        Pattern pattern = Pattern.compile("([A-Z]-\\d{4})");
+        MappedRegexRealmMapper mappedRegexRealmMapper = new MappedRegexRealmMapper(pattern, realmNameMap);
+        Principal principal = new NamePrincipal("A-9999");
+        Assert.assertEquals(realmName, mappedRegexRealmMapper.getRealmMapping(principal, null));
+    }
+}