@Before
  public void setUp() throws Exception {
    Hashtable table = new Hashtable();
    table.put(Context.INITIAL_CONTEXT_FACTORY,
        "org.apache.geode.internal.jndi.InitialContextFactoryImpl");
    initialContext = new InitialContext(table);
    initialContext.bind("java:gf/env/datasource/oracle", "a");
    gemfireContext = (Context) initialContext.lookup("java:gf");
    envContext = (Context) gemfireContext.lookup("env");
    dataSourceContext = (Context) envContext.lookup("datasource");
  }
Tests all basic methods of ContextImpl.
geode-core/src/test/java/org/apache/geode/internal/jndi/ContextJUnitTest.java