public void Test_07_TestGetExtension( )
{
FileFilters filter = new FileFilters( );
string filters = ( "Word (*.doc)|*.doc|WordX (*.docx)|*.docx||" );
filter.PopulateCollections( filters );
Assert.AreEqual( ".doc", filter.GetExtension( 0 ) );
Assert.AreEqual( ".docx", filter.GetExtension( 1 ) );
Assert.AreEqual( "should throw IndexOutOfRangeExctption", filter.GetExtension( 2 ) );
}