@Test
public void testPower4() {

    String inputExpression = "y ** ( 5 * 3 )";
    BaseNode infix = parse( inputExpression, mapOf(entry("y", BuiltInType.NUMBER)) );
    assertThat( infix, is( instanceOf( InfixOpNode.class ) ) );
    assertThat( infix.getResultType(), is( BuiltInType.NUMBER ) );
    assertThat( infix.getText(), is( inputExpression ) );
    InfixOpNode exp = (InfixOpNode) infix;
    assertThat( exp.getLeft(), is( instanceOf( NameRefNode.class ) ) );
    assertThat( exp.getLeft().getText(), is( "y" ) );
    assertThat( exp.getOperator(), is( InfixOpNode.InfixOperator.POW ) );
    assertThat( exp.getRight(), is( instanceOf( InfixOpNode.class ) ) );
    assertThat( exp.getRight().getText(), is( "5 * 3" ) );
    InfixOpNode mult = (InfixOpNode) exp.getRight();
    assertThat( mult.getLeft(), is( instanceOf( NumberNode.class ) ) );
    assertThat( mult.getLeft().getText(), is( "5" ) );
    assertThat( mult.getOperator(), is( InfixOpNode.InfixOperator.MULT ) );
    assertThat( mult.getRight(), is( instanceOf( NumberNode.class ) ) );
    assertThat( mult.getRight().getText(), is( "3" ) );
}