@Test
public void testInvalidNumbers() {        

    try {
        new ExtendedParser("a").readNumber();
        fail("Expected invalid number error");
    } catch (ParserException e) {
        // Expected
    }
    
    try {
        new ExtendedParser("-").readNumber();
        fail("Expected invalid number error");
    } catch (ParserException e) {
        // Expected
    }
    
    try {
        new ExtendedParser("0.").readNumber();
        fail("Expected invalid number error");
    } catch (ParserException e) {
        // Expected
    }
    
    try {
        new ExtendedParser(".0").readNumber();
        fail("Expected invalid number error");
    } catch (ParserException e) {
        // Expected
    }
}