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Frequently Asked Questions
before your test
I got an invitation to take a Codility test.
What is it?
Codility test is an automated test of programming skills. You have been invited to take the test to demonstrate your programming ability on some small coding assignments. You will be presented with a few tasks that will require you to write or correct some code. You can run and test your solutions in our online environment or use your editor of choice.
- Can I open the link now but take the test later?
Yes, you can open the link and read the introductory information. Unless you press "Start the test" button, you can leave and come back when you are ready. Once you start the test, you will not be able to stop the timer.
- How much time does a Codility test take?
Tests usually last between half an hour and two hours. The exact length is set by your recruiter and depends on the number of tasks. Keep in mind that once you begin the test you cannot stop the timer.
- What sort of code will I write during the test?
Each test consists of several tasks that require you to write or modify short programs (usually 10–20 lines). Tasks differ in difficulty and scope. Follow your test link now to view the number of tasks in your test and the list of languages that you can use.
- How will my solutions be assessed?
After you finish the test, we will run your solutions against multiple test cases to verify their correctness (e.g. whether your code handles corner cases) and scalability (whether your code remains practical as the data size grows). Afterwards the results will be presented to your recruiter. See an example report here.
- Will I see my results?
Some recruiters will share the results with you, but others may choose to keep them confidential.
- Do I have to take the test immediately after receiving an invitation?
You should take your test within the next day or two. If you need to delay your test, contact your recruiter.
- Do I need to install any software?
You only need a supported browser. You don’t need to install any applications or browser plug-ins. The Codility interface contains a coding environment that provides everything you need to solve the tasks (you can edit, compile and run your solutions many times before you submit your code). If you prefer to use other programming tools, see Can I use my own IDE?.
- What browsers are supported?
Chrome ≥ 60, ChromiumEdge ≥ 79, Firefox ≥ 59, Opera ≥ 48, Safari ≥ 11.
You must use a supported browser for the test. If we detect that you are attempting the test on an unsupported browser, we will tell you.
during your test
Can I modify the initial code?
Be careful. You need to leave the function signature just as it is provided, because otherwise our assessment engine will not be able to run your program. With that in mind, feel free to add helper functions, imports/includes...
(In some tasks there are extra restrictions on how much code you are allowed to change - the goal is to understand the code and make a minimal edit that fixes the given problem.)
- How can I test my solution before submitting it?
Our environment enables you to compile and execute your code against an example test case. You can add your own test cases too. See how it works in our demo test.
- I clicked ‘Run’ and it says “OK”. Will I score 100%?
That’s not sufficient! Clicking ‘Run’ only verifies whether your code compiles and returns the correct result for the example test case. You need to make sure that your code works correctly and efficiently with all possible inputs.
- May I consult a book/website/colleague?
During the test you should work on your own; you may not consult anybody. You may use books and websites unless your recruiter explicitly tells you not to.
- Can I use my own IDE?
Yes, you can write your solution in an editor of your choice and paste the solution back into the Codility interface. Use the ‘Run’ button to make sure that the code has been copied properly and that Codility is able to compile and execute it. Your compiler is not necessarily the same as ours, so remember to write portable, standards-compliant code. The supported language version is displayed in the Codility interface.
- Should I verify the validity of input data?
No, you don’t need to check whether any assumptions given in the task are true.
If we say, for example, that N is a positive integer, your code does not need to verify that it really is.
Will my coding style affect my score?
Yes. Your recruiter may read and review your code and your style may be taken into account when computing your final score.
- How do I save my code?
Codility saves your code automatically. If you close the browser window and open it again, you will resume where you left off. When you have completed one of the tasks and you are sure your solution is ready, click the ‘Submit’ button. Note that you won’t be able to modify this task’s solution after doing so.
- What if I run out of time?
As soon as the time runs out, Codility saves your code and assesses it.
- Will I lose points for syntax errors?
If your final submission doesn’t compile, we won’t be able to assess your program and you will not get any points. Be sure to use the ‘Run’ button to check for compilation errors while working on the solution. See How can I test my solution before submitting it?
- How many points did I score?
Please contact your host for any feedback related to your Codility session, also in the context of the recruitment process you participate in.
What is CodeLive?
CodeLive is a recorded collaborative programming session. You will be able to work together on programming questions selected by your host.
- My CodeLive session is not active yet - when will I be able to enter?
Once your host starts the session you will be able to enter. If you are having a problem entering the CodeLive session, please contact your host to allow you to enter.