Black Box vs White Box Testing: What are the Key Differences?
Accentuating both quality and security while developing applications is the need of the hour. It helps ensure your application is free from all possible flaws and security loopholes that might lead to significant revenue losses. And that’s when two testing types come into the picture: black box and white box. They both undertake many functional and non-functional aspects of an application, and people often discuss them in competition. So, we have come up with a black box vs white box testing guide for you.
Table Of Contents
What is Black Box Testing?
Types of Black Box Testing
Black box testing mainly comprises three types of testing:
Functional testing: It involves testing specific functions or features of software under test. Functional testing includes unit testing, smoke testing, sanity testing, integration testing, and user acceptance testing.
Non-functional testing: It involves testing additional aspects of the software that are beyond features and functionalities. It helps check how well a system performs under high load and different environments. Non-functional testing includes performance testing, load testing, stress testing, volume testing, and security testing.
Regression testing: It involves testing the new version of software for any regression or degradation in capabilities. It can be applied to both functional and non-functional aspects of the software.
What are the Black Box Testing Techniques?
Testers use different techniques of black box testing based on the requirement:
Equivalence partitioning: In this technique, the inputs are divided into different groups or partitions, and one input from every group is tested to find the results.
Boundary value analysis: As the name suggests, the tests in this technique are designed to include representatives of boundary values (inner and outer limits) in a range.
Decision table testing: This technique helps test the system’s behavior for different input combinations. As the name suggests, the inputs are represented in tabular form.
State transition testing: It is a technique used to test different states of the system. It works well when there are different responses during the transition from one state to another.
Error guessing: The testers use this technique to guess the error-prone areas based on the application’s behavior and functionalities.
Example of Black Box Testing
Let’s quickly take a look at an ideal example of black box testing.
Imagine a situation where you are looking to buy a new car, and you have done a bit of research to come up with 3 options that suit your needs and budget. Now, how will you evaluate these 3 options that you have to finally choose the best from the lot?
You will most probably take test drives to find the best one. Here, you are not concerned about the internal machinery of the car. Instead, you rely on usability and functionality to reach a conclusion.
That’s exactly how black box testing works—analyzing the functional aspects of software.
Advantages of Black Box Testing
- It can easily be performed by testers with no technical background or programming knowledge.
- It can start as soon as the functional specifications are complete.
- Both the testers and developers work independently, so the testing is balanced and unbiased.
- It helps identify the defects and inconsistencies in the early stages of testing.
Disadvantages of Black Box Testing
- There is a high chance of not achieving any result at the end of the test.
- Writing test cases is slow and difficult as identifying all possible inputs in a limited time becomes challenging.
- It is not ideal to use for large and complicated applications as complete test coverage is not possible.
- As it is specification-dependent, building test cases without specifications become difficult.
What is White Box Testing?
White box testing is a type of software testing wherein the internal structure and design of the item being tested are well known to the tester. It helps the developers in finding out the internal flaws of the security.
Types of White Box Testing
Conditional testing: This type of testing checks the logical conditions for both true and false values.
Path testing: It is a testing approach that uses the source code of a program to find every possible executable path. It helps the testers achieve maximum path coverage with the least number of test cases.
Unit testing: It is a testing method wherein individual units of software are tested. It helps ensure that each component of the software works as intended.
Integration testing: It is a type of testing process in which individual software modules or components are tested as a group. It helps ensure that the modules work fine when merged.
Loop testing: This testing type that entirely focuses on validating the loop constructs used in the algorithms.
Know in detail here about Different Testing Types
What are the White Box Testing Techniques?
Testers use different techniques of white box testing, including:
Statement coverage: This technique makes sure that all executable statements in the code are run and tested at least once.
Branch coverage: In this technique, the code is mapped into the branches of conditional logic and ensures that unit tests cover every branch.
Path coverage: In this technique, the tester writes unit tests to execute all the possible paths through the program’s control flow in order to identify broken, redundant, and inefficient paths.
Control flow testing: It is a structural testing technique that helps determine the execution order of statements of the program through a control structure.
Example of White Box Testing
To understand white box testing better, let’s consider an example.
Imagine a situation wherein a customer needs to transfer money to a friend who lives abroad. S/he wants to use the mobile banking service provided by their bank to do this.
Testing the service involves identifying all the possible paths to help increase the test coverage, such as:
- Is the customer allowed to transact in the selected currency?
- Does the friend’s account exist as a beneficiary?
- Is the amount to be transferred within the transaction limit?
- Is the customer subject to any local or international sanctions or limits?
This is how white box testing works—by analyzing the internal functionality.
Advantages of White Box Testing
- White box testing helps find hidden errors in an application as it checks and works by internal functionality.
- It is much more thorough than traditional black-box testing.
- It helps get maximum test coverage while writing test scenarios, as the tester has programming knowledge.
Disadvantages of White Box Testing
- White box testing is an exhaustive method of testing as it takes a significant amount of time to develop the test cases.
- It might miss testing certain functionalities as only the available code is tested.
- It requires skilled testers having programming knowledge to perform white box testing.
- It is costly as compared to black box testing.
Key Similarities Between Black Box Testing and White Box Testing
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Both black box and white box testing identify defects in the overall application
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They are performed by the testers who interact with the software to understand its functioning
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Both of them help discover the root cause of the problem
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They both focus on running the software and observing its behavior
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You use them to compare the actual results with expected results
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They both can be automated
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Both of their functions are to ensure that the software works properly
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Black box and white box require clear understanding of software specifications
Black Box vs White Box Testing
| Black Box Testing | White Box Testing |
| It is known as a higher level of testing as it analyzes the functional and non-functional aspects of software. | It is performed at a lower level of testing, for instance, unit testing and integration testing. |
| It is done without any knowledge of the internal system. | It is done to test the internal structure or working of an application. |
| Test cases in this method are based on the requirement specifications document. | Test cases in this method are based on the detailed design document. |
| Testing techniques include equivalence partitioning, boundary value analysis, decision table testing, state transition testing, etc. | Testing techniques include conditional testing, loop testing, control flow testing, data flow testing, branch testing, etc. |
| It is performed by professional testers. | It is performed by developers or testers having coding knowledge. |
| It is the least time-consuming. | It requires a significant amount of time to perform. |
Conclusion
Frequently Asked Questions
Which tool is used for white box testing?
Some of the most popular tools for white box testing are –
- JUnit: It is a testing framework for the Java programming language.
- Cucumber: It is one of the leading tools for BDD (Behavior Driven Development).
What are the tools for black box testing?
Tools that are quite popular among testers for black box testing are –
- Selenium: It is an open-source tool and probably the most common for black box testing in web applications.
- Appium: Appium is also an open-source tool that is fully cross-platform, as it supports both Android and iOS and a wide range of mobile browsers
- Ranorex: It is a commercial tool that is known to automate bug tracking and accelerate your software release cycles
When do we do black box testing?
Black box testing is generally done at the final stages of the testing process to validate the entire software development life cycle. It is done keeping the end-user in mind and helps ensure that the final software is working as intended.
When do we use white box testing?
White box testing is used when testers want to examine the inner workings of software, including code, infrastructure, and integration with external systems. It helps to verify logical conditions and their values and detects bugs at different levels.
