Bug 211839 String grouping unit type needs to support interval range.
Build ID: I20071101-2000 As Chart has supported, the String grouping unit type can be set interval range, the interval range means that the string group will base on row count distinction. For instance, let's say we have a,b,c,d,e,f,g , and set interval range to 2, the grouping result should be a,c,e,g. Now it is a requirement that DtE support the grouping type.
data/org.eclipse.birt.data.tests/test/org/eclipse/birt/data/engine/binding/DataSetCacheTest.java
this.appContextMap.put( DataEngine.DATA_SET_CACHE_ROW_LIMIT, new Integer(4) );
		this.testUseCache1();
	}
	
	/**
	 * Test acquire saved cache result meta 
	 *
	 */
	public void testUseCachedMeta1() throws BirtException
	{
		this.appContextMap.put( DataEngine.DATA_SET_CACHE_ROW_LIMIT, new Integer( 1 ) );
		this.genCache();
		myDataEngine = newDataEngine( );
		IResultMetaData meta = myDataEngine.getCachedDataSetMetaData(dataSource, dataSet);
		assertTrue( meta!= null );
		assertTrue( meta.getColumnCount() == 6 );
	}
	
	/**
	 * Test acqurire inexist save cache result meta 
	 *
	 */
	public void testUseCachedMeta2() throws BirtException
	{
		this.appContextMap.put( DataEngine.DATA_SET_CACHE_ROW_LIMIT, new Integer( 0 ) );
		this.genCache();
		myDataEngine = newDataEngine( );
		IResultMetaData meta = myDataEngine.getCachedDataSetMetaData(dataSource, dataSet);
		assertTrue( meta == null );