import _ast
import unittest


def srcExprToTree(source):
    return compile( source, '<module>', 'eval', _ast.PyCF_ONLY_AST )



class ASTTest (unittest.TestCase):
    def testAST(self):
        expr = srcExprToTree( 'a < b < c' )
        compare = expr.body
        self.assert_( isinstance( compare.ops[0], _ast.Lt ) )
        self.assert_( isinstance( compare.comparators[0], _ast.Name ) )
        self.assert_( isinstance( compare.ops[1], _ast.Lt ) )
        self.assert_( isinstance( compare.comparators[1], _ast.Name ) )
        self.assert_( isinstance( compare.ops[1:][0], _ast.Lt ) )
        self.assert_( isinstance( compare.comparators[1:][0], _ast.Name ) )
        z = zip( compare.ops[1:], compare.comparators[1:] )
        self.assert_( isinstance( z[0][0], _ast.Lt ) )
        self.assert_( isinstance( z[0][1], _ast.Name ) )
        
        



if __name__ == '__main__':
    unittest.main()