As you heard from lecture, debugging is a very useful and necessary tool for developing software and solving problems. In this homework assignment you will be tasked with fixing errors in serveral methods. Each method solves a different problem such as finding the minimum in an array or running a binary search. The algorithm for each problem will be given, but there are small bugs littered in the code preventing the test cases from passing.
This homework will be due on 10/2/2020.
You will know that you have finished when all the test cases pass and your code is visible on GitHub. There will be hidden test cases that checks for any hardcoded solutions.
Picture this: You land a great internship as a Freshman thanks to all the skills you learned in CS193, and are put to the task of picking up where last year's IU intern left off.
Needless to say, they've left a mess of things. It's up to you to identify what's wrong with their code!
Without getting too deep into the commands of git, we want to "clone" our repository and edit it locally like any other file (if you are interested, check out this guide)
IntelliJ has a great deal of support for exactly this! We can store a local version of our repository, and push any changes to the remote repo easily!
- Close any projects you currently have open
File -> Close Project
You should now see the main IntelliJ screen (It looks like the picture below).
NOTE: If you just clone without letting IntelliJ configure everything for you, it's a pain in the butt to fix. Please let IntelliJ create everything for you!
- Checkout a project from Version Control. This is done from the welcome screen in Intellij!
Click Check out from Version Control -> Git -> Log in to GitHub...
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Click 'Clone'
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Enter your GitHub credentials if asked for. (Note: The order of steps 3 and 4 might be flipped)
- Confirm checkout from version control. Click 'yes'
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IntelliJ will now ask you if you want to customize setup or rely on the default. You can just click 'Yes' or 'Confirm' on the screens that follow
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Make some changes to the documents
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- Configure IntelliJ for JUnit
You just need to hit ALT + ENTER and choose "Add JUnit4 to classpath". ALT + ENTER is your friend in IntelliJ :)
- Run all the test cases
You can run all test cases by right clicking the test case file.
is good, because you passed all checks
means you got a wrong result in a test case
means an exception was encountered when running the case
- Run a particular test case
You can also isolate a single test case and run only that one by right-clicking it.
This results in:
- Find the line where it goes wrong
Once the test case fails, you can pinpoint the exact issue by double-clicking the failed case. This will show you either the assert statement you got incorrect, or the line where an exception was encountered.
- Set method and line breakpoints and start test case in Debug mode
Set some breakpoints in the methods you suspect this test case has touched, and then run the test case in Debug mode.
- Continue stepping through the code and find the issue
You can see the step-by-step execution of your code, as well as the values of variables and how they change.
To move onto the next breakpoint sector, you have to resume the program.
- Take advantage of the information you find, and just keep stepping!
Use print statements, the debugger, or any strategy you'd like to fix the bugs in the methods and pass the test cases. You might also want to try to understand the algorithms, such as binary search, as they commonly show up in technical interviews (although you're not required to do this). You are NOT allowed to make any changes to the testcase file. If you feel there is a need to make changes, please email your TA or post on Piazza. It will be an automatic 0 if changes are made
Click here for Intellij's debugger documentation
- Commit and push your changes. Note: Depending on version, the pull and commit may look like blue and green arrows instead.
- Confirm you'd like to push changes
NOTE: Each time you open this project, you should PULL to make sure your local repository is up to date with the remote repository
As with every other homework, if your code isn't on GitHub we won't be able to grade it! Once you're happy with the fixes you've made to the code (likely when all the test cases pass), save your work to GitHub.
The last 4 questions will be extra credit totalling up to 5 extra credit points!! We encourage you all to try it out.
| Task | Points |
|---|---|
| Task 1 | 2 |
| Task 2 | 2 |
| Task 3 | 3 |
| Task 4 | 3 |
| Task 5 | 5 |
| Task 6 | 5 |
| Task 7 | 2(EC) |
| Task 8 | 1(EC) |
| Task 9 | 1(EC) |
| Task 10 | 1(EC) |
| Total | 20 |
As always, feel free to ask questions on piazza, in pso, and/or office hours. Good luck!