Difference Between Testing and Debugging

What is the Difference Between Testing and Debugging [2024 Updated]

As programmers, although we know how to code a program, we often don’t know the technical terms related to it. But considering how often they’re thrown around, it’s handy to know some important ones. If you’re new to coding, you might not know the difference between testing and debugging yet. 

Debugging is when you know your code has a bug, and you implement techniques to find it out. Whereas Testing is when you’re not aware of any certain bug, but are in search of finding one, just in case one pops up. 

Both processes include being patient and making your piece of software as error and bug-free as possible. Throughout this post, we’ll delve deeper into the topic and provide tips on optimizing both processes. 

Comparison Table of Testing and Debugging

Before going into the detailed explanations of testing and debugging, let’s first articulate testing vs debugging into a neat table: 

It’s the process of checking if a bug exists.It’s the process of eliminating the bug after it has been found during testing
Testing doesn’t necessarily need to be done by a programmer Debugging must be done by a programmer, preferably the person who wrote the code
No programming or design knowledge is requiredProgramming knowledge is a must, and design knowledge helps
Testing isn’t secretive: anyone outside the company may be allowed to testDebugging is strictly secretive and must be done by people within the company
It can be automated or manualIt’s strictly manual
Testing can be done even after a project is completeDebugging is done while developing a project
Costs of labor and buying testing tools are included.It doesn’t cost anything, besides the efforts of the programmer

Difference Between Testing and Debugging: In-Depth Comparison

As mentioned in our one-liner, debugging is knowing actively that an error exists and trying to exterminate it, whereas testing is setting out on a journey of trying to find any perceivable error. Let’s now get into the nitty-gritties of testing vs debugging. 

What is Testing?

Testing is the process of making sure that a piece of software is completely error-free. This activity isn’t necessarily done by the programmer himself but rather can be outsourced to someone else who has ideas about a project. 

Features of Testing

While testing, quite literally every possible incurable scenario is emulated. In input fields, values that a user might not usually put in are entered just to check if the code can handle it. Corner cases are checked, like whether integer overflow occurs and how the software deals with it. Out-of-bounds and other boundary cases are examined too.

Testing features also include checking design requirements, judging how well the software interacts on different sets of devices, and so on. 

Overall, testing examines and verifies whether a program is ready enough to be published publicly and for the users to use so that there’s no room for them to send in complaints.

Types of Testing

Testing is systematically carried out depending on the category. Depending on the tester, testing is of two types: manual and automated testing. 

Manual Testing 

As the name suggests, manual testing is done manually by a human being. They don’t necessarily have to be software programmers or have coding knowledge, but it obviously helps. 

The only required knowledge is the steps for software testing going through the program and testing every bit of nook and cranny in search of a bug.

Manual testing is quite expensive, as you’re using human time and might need to pay the testers at an hourly rate. Humans are also not the most efficient, and it’s easily possible for the human tester to leave out certain cases or that bugs don’t catch their eye. 

Sub-category: Beta Testing

To mitigate this, some popular companies make smart of their big fan base. When launching an app, they start a beta testing campaign, where enthusiast fans get to try out the app before anyone else, play around with it, and report back to the developers if they find anything fishy. 

One of the most popular apps now, Discord, has its own beta testing campaign, where the community chimes in and help the developers.

This is a win-win strategy in both ways: the fans feel included in the company’s decision-making process, and the company just got real human testers without having to pay a professional.

Automated Testing 

The exact opposite of manual testing, automated testing includes using special computer programs or artificially intelligent algorithms to test their programs for them. This approach is much quicker and can handle higher datasets in less time. The script for automated testing is written by the programmer, who tries to go through every use case possible and test his software on rigorous workloads. 

A downside of automated testing is the lack of human touch. As everything is done with yes’s and no’s, it’s not quite possible to know how a user would perceive or encounter the error. Furthermore, the automated script writer knows beforehand which errors to look out for. So it has its pros and cons. 

In the second category, we have the actual processes carried out while testing on different components of the software, such as: 

  • Unit Tests: As the name suggests, unit tests deal with testing the fundamental “unit” elements of the software, such as the main functions, classes, components, and models. These can easily be carried out through automated testing. 
  • Integration Tests: This checks the inter-processes integration between various elements of the software and verifies if everything is working in proper synchrony. 
  • Functional Tests: Following suit of integration tests, functional tests verify the actual functioning capability of the element, i.e, whether it’s returned the expected output to the user. In these checks, the functionality the element provides to the user is checked.
  • End-to-end Tests: This is the complete package: checking if the software is ready to handle multiple users, logins, and multiple queries at once without errors.
  • Acceptance Tests: The business acceptance tests check if the software was made within the set guidelines of the company and is ready to be put to use in a business.
  • Performance Tests: This handles the performance of the software across various machines, which includes website response time, CPU usage, memory usage, query complexity and efficiency, and such.
  • Smoke Test: The final of the most common tests, smoke testing, is quick and short, checking whether the program is functioning and providing the basic expected output. After passing smoke tests, usually more complicated, expensive tests are run. 

What Are The Steps for Automated Software Testing?

The ways for testing a piece of software will differ from company to company and the type of software, but all follow a similar suite as follows:

  • Step 1: A Smoke Test and overall overview of the code is run before running it, checking for generic bugs.
  • Step 2: Unit tests are run, checking the software more deeply.
  • Step 3: Integration tests are done across various machines and display sizes.
  • Step 4: End-to-end tests are done. Afterward, a performance test is done, and a performance tabulation is created.
  • Step 5: With the performance sheet in hand, the software is sent out for acceptance testing. When it’s passed, it’s declared to be ready for making public.

How to Optimize Testing Process

To optimize the steps for software testing, you, of course, have to first figure out which types of testing would work well for your project or software. Automated tests take far less time and money, and will make your testing process both cheaper and more efficient. Later on, you can implement the following: 

  1. Create an action plan with the type of your software and what testing schemes it would benefit from. A structured plan will help shorten the time and ensure you check out all the boxes while testing. 
  2. Start with test automation by first automating the processes which can easily be run via a script. This will not only save money, but also a large chunk of your time. You’ll also be able to carry out more tests in a shorter period of time. 
  3. Implementing testing tools is also important. For simpler tests, you can get the head programmer to write a simple script. But for other tests, investing in a proper testing tool is imperative. Find a tool that was made for your business category and see if it can be employed to test your software.
  4. Getting the right people on board is crucial; they know about the project and can add a human touch to your testing process. But be sure to automate as many processes as possible and leave a selected few for your employees. 

What is Debugging?

Debugging is what comes after testing. Once you’ve found a bug in your software in the testing phase, now it’s the work of the programming team to look through the code and fix the code. 

Features of Debugging

The programmer who wrote the piece of code where the error had been found is usually the one who carries out the debugging. He first reads the entire code carefully, checks for basic errors, and runs stress tests on the code to find out which block of code is causing the error. 

Once found, either the block of code is rewritten or tweaks are made to handle and fix the edge case for the bug. 

Debugging is a time-consuming process. Although the block of code at fault may only be 30 or so lines in length, figuring out where the problem lies usually takes more than 30 minutes. 

The programmer has to brainstorm and truly dig deep to find why a line of code isn’t behaving the way it should be. And in the end, the features of debugging are set by the programmer himself.

Types of Debugging

Usually, the programmer already has the experience and debugs a code in his certain, unique way. Often this is done unconsciously, without following any specific type, but the debugging approaches always fall into certain categories:

Brute Forcing

Making quite literal use of the name, brute force means using multiple print statements, for loops, and such within the code and manually figuring out the values almost every variable is producing. Once the programmer has all the data, he can usually spot if something is off. 

This is by far the least efficient method, but also by far one of the most popular techniques used by programmers. Nowadays, multiple print statements or loops aren’t necessarily needed, as modern editors like Visual Studio Code already have built-in, more advanced brute force debuggers.


This includes first finding an error-prone block of code and running the code backward manually to find whether values, variables, or processes are not working how they’re supposed to. This can be helpful in short blocks of code, but as they get longer, the amount gets overwhelmingly large and isn’t a viable option anymore.

Crossing Out Checklist of Causes

Here, a checklist is created at first with all possible causes that may have led to the problem. Next, the programmer tests each problem, crossing them out from the checklist in hopes that the exact error will be found.

Stress Testing

A popular approach of debugging is stress-testing. It implies testing the main, efficient code, yet flawed code against an inefficient, yet almost fool-proof correct code. Usually, with trying to optimise the complexity of a code, some corner cases are left out. Stress testing simultaneously compares the wrong efficient code and the right inefficient code and compares their output to see if their outputs differ. Once the programmer knows for which test case his code has failed, it’s easily for him to find the bug or create separate exception-handling.

Slicing a Program

In the last type of debugging, here, the program is sliced or cut up into different parts, and each part is thoroughly checked at once. The slicing is done in such a way that part 2 is independent of part 1, and part 1 has been checked and declared error-free before moving on to part 2. 

What Are The Steps of Debugging

The steps of debugging are pretty straightforward, and every programmer does it in his own way. But usually, it looks like this: 

  1. After finding the bug, identify which block of the code is responsible for it. 
  2. Slice the program and highlight the block of responsible code.
  3. Brainstorm and find a fix for the code using the different approaches of debugging.
  4. Re-run and re-test to see if the bug has been fixed. 

How to Optimize The Debugging Process

Debugging is a must-have of any programming project. No matter how good of a programmer you are, you can’t really avoid it, it’s a natural part of programming to make mistakes. That being said, you can be smart about how you carry out debugging so that you don’t have to do too much at the very end. 

Test Code in Small Blocks From The Start

Experienced programmers often follow this, where they test out their code as they go. A final can have anywhere from 500 to 800 lines of code in a large project. Rather than testing it at the very end and struggling to debug all 500 to 800 lines, it’s better to test every now and often to see if everything’s in shape. 

After implementing a feature of, say, 50 to 100 lines, test it at the very spot. If you find errors, it’d now be easier to debug. 

Use A Modern Code Editor

Editors such as Visual Studio Code, PyCharm, and similar nowadays have built-in debuggers. These show values of variables, which variables are being passed into functions and processes natively in the editor. This brings down the work of the programmer and makes brute force debugging a much smoother process.

Sit With A Pen And Pencil

Sometimes, manually running the code by hand saves a lot of time in comparison to looking at a screen and banging your head for a solution. Try drawing and sketching the graphs and trees on a piece of paper and emulating the code. Then, you can move on more systematically and find the bug much easier.

Use a Debugging Tool

Debugging tools are highly helpful if you’ve just gotten into debugging and aren’t quick or confident enough with brute force debugging. The top three popular debugging tool sets are: 

  1. GDB: This is a built-in tool found in Linux. If you’re already on linux, this is the way to go. It’s used in Unix Programming and is a more versatile debugging tool, with tons of commands which can be run with huge flexibility. It doesn’t have a GUI.
  2. DDD: It stands for Data Display Debugger, and is the GUI version from GDB. For beginners who aren’t yet comfortable with the versatile command prompt from Linux, the GUI version can be less intimidating and still get the job done.
  3. Eclipse: Eclipse can be found in both Linux and Windows. It mainly includes IDE’s, which in themselves have tons of debugging tools, like pre-highlighting, showing values of variables off the top, clicking to view calculations and variables at use currently, and much more. In this category, modern IDEs such as CodeBlocks, JetBrains IDE, PyCharm, and so on are included. 

As a beginner, it’s usually recommended to start off with an IDE, although they might be more heavy-weight.

Frequently Asked Questions

If you have any more questions, check out the FAQs below to have your queries cleared.

What are the stages of testing?

The general stages of testing are unit tests, integration tests, performance tests, functional tests, end-to-end tests, and finally, acceptance tests. To learn them in detail, refer to the Stages of the Testing section in our article. 

What are the 4 levels of testing?

The 4 levels of testing include the Unit Test, which is first done with the code, and the Integration Test, done to check compatibility and integration on various platforms. Then comes the System Test, testing the entire system. Finally, it’s sent out for the Acceptance Test, and verified if it fulfilled all the given guidelines. 

What are the stages of debugging?

Simply put, the debugging phase looks as follows:

  1. Identify the bug
  2. Find the block of code responsible for it.
  3. Isolate the block and find the error.
  4. Fix the error.
  5. Run a re-test.

What are the benefits of debugging?

Debugging ensures that a code is bug-free and prevents future bugs or undefined behavior from occurring in the future.

What are the debug tools?

Debug tools are either native code editor tools or external third-party software manually integrated into the code editor to aid in the manual debugging process. Most modern-day editors such as Visual Studio Code or JetBrains already have built-in debugging tools.

What are the testing tools?

Testing tools are special software created to automate the testing process. Depending on the type of business or aim of the software, a testing tool helps cross out every testable element of that software and shows errors if found. Usually, testing tools cost money, but save a lot of time and can run a lot of tests in a short amount of time. 

Wrapping Up

In the end, testing and debugging are dependent on each other. Debugging takes place only after testing has been successfully completed. And if a programmer has programmed everything carefully and debugged beforehand, ensuring no failures and errors, the testing process is short and doesn’t need much effort. 

Overall, every software project has some form of testing and debugging in place. As novices, it’s important to know their differences, and how to carry them out successfully. This is what we hope you have taken away the difference between testing and debugging from this article. Good luck with your coding projects!

Rahnuma Tasnim

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