Integration Testing with ContextTestCase

[feester]

About a month ago--I don't remember where--someone provided a JUnit TestCase implementation that loaded a Spring ApplicationContext then set instance variables via java reflection. I liked the concept, but have come up with a couple of refinements of my own. Maybe others will find following implemenation useful.

ContextTestCase will only load the ApplicationContext once, for a test class. If all the test classes in a test suite have same context files then ApplicationContext only loads once for the entire test suite. If the context files change from test class to test class a new ApplicationContext will be loaded/reloaded as needed.

First, create a test class that inherits from ContextTestCase.

To initialize the context call initialize method in setUp():

  public void setUp() throws Exception
  { 
    initialize( "contextFile1.xml,contextFile2.xml" );
  }

To get an instance to test call getBean():

  public void testMethod() throws Exception
  {
    final MyClass ref = (MyClass)getBean("myClassBean");
    // proceed to test
  }

Hope you find following implementation useful:

import java.util.StringTokenizer;
import junit.framework.TestCase;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

/**
 * A JUnit TestCase extension that simplifies integration testing by making
 * available a Spring application context.  This class short-circuits the 
 * 'set all instance variables null before every test method' mechanism in favor 
 * of loading Spring environment only once before executing any test methods.
 */
public class ContextTestCase extends TestCase 
{
  private static String[] contextFiles = null;
  private static ApplicationContext context = null;
  
  protected final static Object getBean( String bean )
  {
    return context.getBean(bean);
  }

  protected final static ApplicationContext getContext()
  {
    return context;
  }
  
  /**
   * Alternate form to initialize/load context
   * @param xmlFiles in comma delimited string
   */
  protected final synchronized void initialize( String xmlFiles )
    throws Exception
  {
    String[] contextFiles = toStringArray( xmlFiles );
    initialize(contextFiles);
  }
  
  /**
   * @param xmlFiles  context files that specify objects available 
   *                  in Spring application environment.
   */
  protected final synchronized void initialize( String[] xmlFiles ) 
     throws Exception
  {
    if( context == null || !same( xmlFiles, contextFiles ) ) {
      contextFiles = xmlFiles;
      context = new ClassPathXmlApplicationContext( xmlFiles ); // load context
      
      StringBuffer msg = new StringBuffer&#40;"<<< CONTEXT LOADED >>> &#91;"&#41;;
      for&#40; int i = 0; i < xmlFiles.length; i++ &#41; &#123;
        if &#40; i > 0 &#41; &#123; msg.append&#40;" "&#41;; &#125;
        msg.append&#40; xmlFiles&#91;i&#93; &#41;;
      &#125;
      msg.append&#40;"&#93; IN class='"&#41;;
      msg.append&#40; this.getClass&#40;&#41;.getName&#40;&#41; &#41;;
      msg.append&#40;"'"&#41;;
      System.out.println&#40; msg.toString&#40;&#41; &#41;;
    &#125;
  &#125;
   
  private boolean same&#40; String&#91;&#93; files1, String&#91;&#93; files2 &#41;
  &#123;
    boolean ret = true;
    ret = files1 != null && files2 != null && files1.length == files2.length; 
    // true if both not null & same length arrays
    
    // loop stops if ret==false
    for&#40; int i = 0; ret && i < files1.length; i++ &#41; &#123; 
      ret = files1&#91;i&#93;.equals&#40; files2&#91;i&#93; &#41;;
    &#125;
    return ret;
  &#125;
  
  private String&#91;&#93; toStringArray&#40; String listing &#41;
  &#123;
    String&#91;&#93; ret = null;
    
    StringTokenizer t = new StringTokenizer&#40; listing, "," &#41;;
    final int count = t.countTokens&#40;&#41;;
    ret = new String&#91;count&#93;;
    
    for&#40; int i = 0; i < count; i++ &#41; &#123;
      ret&#91;i&#93; = t.nextToken&#40;&#41;.trim&#40;&#41;;
    &#125;
    return ret;
  &#125;
&#125;

[mperham]

You might find this interesting also:

http://opensource.atlassian.com/conf...bled+test+case

[rstearns01]

I've been using the SpringEnabledTestCase for a couple months, but I've relegated it to a integration-type test due to:
a) the time it takes to parse the xml file(s)
b) I dislike the dependence on the IoC container for unit tests

Normally I only have a couple collaborators to mock/stub, and I use DI rather than DL, so I just wire it by hand in setUp().

I also stash the target in an instance variable to avoid repetitions of:

final MyClass ref = (MyClass)getBean("myClassBean");

in each test method.

I like the improvement of only building the context once, though. Thanks!

Regards,

Randy