CSCI 2134 Assignment 3
Due date: 11:59pm, Friday, March 19, 2021, submitted via Git
Objectives
Practice debugging code, using a symbolic debugger, and fixing errors.
Preparation:
Clone the Assignment 3 repository
https://git.cs.dal.ca/courses/2021-winter/csci-2134/assignment3/.git
where is your CSID.
Problem Statement
Take a piece of buggy code, debug it, and fix it.
Background
You have inherited some buggy code for computing shortest path solutions to the board game
Ticket to Ride. Your boss has fired the previous developer because they did not do any testing
and did not fix the bugs! She has hired you to debug and fix the code. She will provide you with
some unit tests (some of which fail), sample input and sample output of what should be produced.
Your job is to fix the bugs: Both the bugs exhibited by the unit tests and the ones by the
input. Good luck!
You will be provided with a full buggy codebase for JSON comparison, a specification, a set of unit
tests using JUnit5, sample input and expected output. Your job is to identify and fix all the bugs.
Given a game board of rail segments and a list of routes (pairs of cities), the code is supposed to
compute the total cost of building a network between the given routes, assuming that the shortest
distance for each route is chosen. This can be computed by computing shortest paths for each
route using Dijkstra’s shortest path algorithm.
You will be provided with a full buggy codebase for distance computation, a specification, a set
of unit tests using JUnit5, sample input and expected output. Your job is to identify and fix all
the bugs.
Task
1. Review the specification (specification.pdf) in the docs directory. You will absolutely
need to understand it and the code you are debugging. The main method for the program
is in RouteCost.java. Note that your boss finally got the buggy makeTree method in
City.java from the previous developer. Spend some time tracing through the code and creating
a diagram of how the classes and code are put together. This will help you a lot later on!
2. Fix all bugs that are identified by the tests generated by the unit tests in the following classes:
• City.java
• CityComparator.java
• Link.java
3. See buglist.txt file in the docs directory. One sample entry is included. For each bug
that you fix add an entry to this file that includes:
a. The file/class name where the bug was.
b. The method where the bug was
c. The line number(s) where the buggy code was
d. A description of what the bug was
e. A description of what the fix was.
4. The previous developer made a set of example input and expected output in the input_tests
directory. These tests will likely not pass yet even after fixing the bugs identified
by the unit tests.
• See the README.txt in this directory for help running the tests. The easiest method is to
copy your .java files from src to this directory and run the test.sh script in a terminal or git
bash command line shell.
• Compare the output in the .out files with the expected .gold files.
• For each output that differs from the expected output, debug the code and determine
the reason for the mismatch. Fix any identified bugs missed by the unit tests.
5. Record any new bugs found and fixed from Step 4 in the previously created buglist.txt
6. Commit and push back the bug fixes and the buglist.txt file to the remote repository.
Submission
All fixes and files must be committed and pushed back to the remote Git repository.
Grading
The following grading scheme will be used:
Task 4/4 3/4 2/4 1/4 0/4
Bugs found
[unit tests]
(20%)
4 to 5 bugs are
correctly identified
and documented.
Three (3) bugs
are correctly
identified and
documented.
Two (2) bugs
are correctly
identified and
documented.
One (1) bug is correctly
identified
and documented.
Zero (0) bugs
are correctly
identified and
documented.
Bugs fixed
[unit tests]
(20%)
4 to 5 bugs are
correctly fixed.
All unit tests
pass.
Three (3) bugs
are correctly
fixed.
Two (2) bugs
are correctly
fixed.
One (1) bug is correctly
fixed.
Zero (0) bugs
are correctly
fixed.
Bugs found
[input tests]
(20%)
2 to 3 bugs are
correctly identified
and documented.
N/A One (1) bug is
correctly identified
and documented.
N/A Zero (0) bugs
are correctly
identified and
documented.
Bugs fixed
[input tests]
(30%)
2 to 3 bugs are
correctly fixed.
All input tests
pass.
2 to 3 bugs are
correctly fixed.
One (1) bug is
correctly fixed.
Some input
tests pass
N/A Zero (0) bugs
are correctly
fixed.
Document
[buglist.txt]
Clarity
(10%)
Document
looks professional,
includes
all information,
and easy to
read
Document looks
ok. May be
hard to read or
missing some
information.
Document is
sloppy, inconsistent,
and has
missing information
Document is very
sloppy with significant
missing information
Document is
illegible or not
provided.
Hints
1. You will need to use a symbolic debugger to make headway. Using print-statements will be
possible but extremely painful.
2. You will need to step through the code to find the bugs.
3. There are about 2-3 bugs in the code (in addition to the ones identified by the unit tests). The
single bug report should cover all of them.