Welcome to the Treehouse Community

The Treehouse Community is a meeting place for developers, designers, and programmers of all backgrounds and skill levels to get support. Collaborate here on code errors or bugs that you need feedback on, or asking for an extra set of eyes on your latest project. Join thousands of Treehouse students and alumni in the community today. (Note: Only Treehouse students can comment or ask questions, but non-students are welcome to browse our conversations.)

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and a supportive community. Start your free trial today.

Java Unit Testing in Java What to Test Rules rule!

Exercise timeout

Hi, I am trying to resolve exercise (it is the second exercise) in third part of the Unit Testing in Java course. But the exercise always times out and offers reload - but after that times out again.

Please can you help me - is there a problem with my code, or is the exercise bugged? Thank you. Petr

package com.teamtreehouse.vending;

import org.junit.Before;
import org.junit.Rule;
import org.junit.Test;
import org.junit.rules.ExpectedException;

import static org.junit.Assert.*;

public class AlphaNumericChooserTest {

    private AlphaNumericChooser chooser;

    // I added this rule setup code for you, thank me later. ;)
    public ExpectedException thrown = ExpectedException.none();

    public void setUp() throws Exception {
        chooser = new AlphaNumericChooser(26, 10);

    public void validInputReturnsProperLocation() throws Exception {
        AlphaNumericChooser.Location loc = chooser.locationFromInput("B4");

        assertEquals("proper row", 1, loc.getRow());
        assertEquals("proper column", 3, loc.getColumn());

    @Test(expected = InvalidLocationException.class)
    public void choosingWrongInputIsNotAllowed() throws Exception {

    @Test(expected = InvalidLocationException.class)
    public void choosingLargerThanMaxIsNotAllowed() throws Exception {

    public void constructingLargerThanAlphabetNotAllowed() throws Exception {
        thrown.expectMessage("Maximum rows supported is 26"); 
        new AlphaNumericChooser(27, 10);
package com.teamtreehouse.vending;

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class AlphaNumericChooser extends AbstractChooser {
    private int ALPHA_FIRST = (int) 'A';
    private int ALPHA_LAST = (int) 'Z';

    public AlphaNumericChooser(int maxRows, int maxColumns) {
        super(maxRows, maxColumns);
        int maxAllowedAlpha = (ALPHA_LAST - ALPHA_FIRST) + 1;
        if (maxRows > maxAllowedAlpha) {
            throw new IllegalArgumentException("Maximum rows supported is " + maxAllowedAlpha);

    public Location locationFromInput(String input) throws InvalidLocationException {
        Pattern pattern = Pattern.compile("^(?<row>[a-zA-Z]{1})(?<column>[0-9]+)$");
        Matcher matcher = pattern.matcher(input);
        if (!matcher.matches()) {
            throw new InvalidLocationException("Invalid buttons");
        int row = inputAsRow(matcher.group("row"));
        int column = inputAsColumn(matcher.group("column"));
        return new Location(row, column);


    private int inputAsRow(String rowInput) {
        rowInput = rowInput.toUpperCase();
        return (int) rowInput.charAt(0) - ALPHA_FIRST;


    private int inputAsColumn(String columnInput) {
        int columnAsInt = Integer.parseInt(columnInput);
        return columnAsInt - 1;
package com.teamtreehouse.vending;

public abstract class AbstractChooser {
    private final int maxRows;
    private final int maxColumns;

    public class Location {
        private final int row;
        private final int column;

        protected Location(int row, int column) throws InvalidLocationException {
            if (row > maxRows || column > maxColumns) {
                throw new InvalidLocationException("Invalid Location");
            this.row = row;
            this.column = column;

        public int getRow() {
            return row;

        public int getColumn() {
            return column;

    public AbstractChooser(int maxRows, int maxColumns) {
        this.maxRows = maxRows;
        this.maxColumns = maxColumns;

    public abstract Location locationFromInput(String input) throws InvalidLocationException;
package com.teamtreehouse.vending;

public class InvalidLocationException extends Exception {
    public InvalidLocationException(String s) {