SUBMARINE-551. Add a test of user identity verification

### What is this PR for?
To test the LDAP for user verification.
The user in this open LDAP server can be verified successfully.

### What type of PR is it?
Improvement

### Todos
* [ ] - Task

### What is the Jira issue?
https://issues.apache.org/jira/browse/SUBMARINE-551

### How should this be tested?
* First time? Setup Travis CI as described on https://submarine.apache.org/contribution/contributions.html#continuous-integration
* Strongly recommended: add automated unit tests for any new or changed behavior
* Outline any manual steps to test the PR here.
https://travis-ci.org/github/Eroschang/submarine/builds/703852786

### Screenshots (if appropriate)
![image](https://user-images.githubusercontent.com/43379142/86231254-d92fe400-bbc4-11ea-8000-ed12af7a2f3e.png)

### Questions:
* Does the licenses files need update? /No
* Is there breaking changes for older versions? No
* Does this needs documentation? No

Author: Eroschang <sanchang274@gmail.com>

Closes #337 from Eroschang/SUBMARINE-551 and squashes the following commits:

ff78c95 [Eroschang] Add a test of user identity verification.
cbb9d28 [Eroschang] Add a test of user identity verification.
0fca95a [Eroschang] Add a test of user identity verification.

submarine-commons/commons-unixusersync/src/test/java/org/apache/submarine/commons/unixusersync/EmbeddedLdapRuleTest.java

@@ -35,13 +35,16 @@
 import org.zapodot.junit.ldap.EmbeddedLdapRule;
 import org.zapodot.junit.ldap.EmbeddedLdapRuleBuilder;
 
+import javax.naming.AuthenticationException;
 import javax.naming.Context;
 import javax.naming.NameClassPair;
 import javax.naming.NamingEnumeration;
 import javax.naming.directory.DirContext;
+import javax.naming.directory.InitialDirContext;
 import javax.naming.directory.SearchControls;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Hashtable;
 import java.util.StringTokenizer;
 
 import static org.junit.Assert.assertEquals;
@@ -133,6 +136,36 @@ public void testList() throws Exception {
     context.close();
   }
 
+  @Test
+  public void testauth() throws Exception {
+    DirContext ctx = null;
+    Hashtable<String, String> HashEnv = new Hashtable<String, String>();
+
+    String loginId = "uid=curie,dc=example,dc=com";
+    String password = "password";
+
+    HashEnv.put(Context.SECURITY_AUTHENTICATION, "simple");
+    HashEnv.put(Context.SECURITY_PRINCIPAL, loginId);
+    HashEnv.put(Context.SECURITY_CREDENTIALS, password);
+    HashEnv.put(Context.INITIAL_CONTEXT_FACTORY, "com.sun.jndi.ldap.LdapCtxFactory");
+    HashEnv.put("com.sun.jndi.ldap.connect.timeout", "3000");
+    HashEnv.put(Context.PROVIDER_URL, "ldap://ldap.forumsys.com:389");
+
+    try {
+      ctx = new InitialDirContext(HashEnv);
+      LOG.info("Pass");
+    }
+    catch (AuthenticationException e) {
+      LOG.error(e.getMessage(), e);
+    }
+    catch (javax.naming.CommunicationException e) {
+      LOG.error(e.getMessage(), e);
+    }
+    catch (Exception e) {
+      LOG.error(e.getMessage(), e);
+    }
+  }
+
   @Test
   public void testContextClose() throws Exception {
     final Context context = embeddedLdapRule.context();