Black Box vs. White Box Testing (What's the Difference?)

By Indeed Editorial Team

Published May 14, 2022

The Indeed Editorial Team comprises a diverse and talented team of writers, researchers and subject matter experts equipped with Indeed's data and insights to deliver useful tips to help guide your career journey.

A software development team can perform black box and white box testing to remove errors from a program's coding language and enhance the quality of a final product. It's important for a software professional to understand how these processes work to include them in a development process successfully. By learning the differences between these types of tests, you can determine which options can best address your needs. In this article, we discuss what black box vs. white box testing is, discover the differences between them, look at examples of different types of tests and the benefits of each one.

Understanding black box vs. white box testing

When attempting to understand the difference between black box vs. white box testing, it's helpful to look at what each testing method is.

Black box testing

Black box testing is a software testing method that a user can perform without programming knowledge or an understanding of the internal structure of a test item. Black box testing solely checks to see if a program is functional. It does not test if the program does what programmers designed it to do. Black box testing is quick, and users commonly complete it using trial and error. An example of black box testing is when users search keywords on Google to test their position in the search ranking.

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White box testing

White box testing is a software testing method in which the tester is aware of the internal structure and design of the test item while testing it. Developers with extensive knowledge of software programming complete white box testing since it's a structural test of the software. This style of testing is time-consuming to complete and tests the logic of the software. An example of white box testing is inputting data and testing to see if your program produces the correct output.

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The differences between black box vs. white box testing

Here are the key differences between black box and white box testing:

Software testers vs. developers

Typically, software testers complete black box testing while software programmers execute white box testing. This is because white box testing requires a higher level of programming knowledge, as the tester checks each line of code to see if it's functional. Black box testing requires less knowledge of programming, as it only tests the outcome. Many companies hire external software testers for black box testing to control what information the testers receive, reducing the possibility of bias in their evaluation processes.

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Usability vs. coding success

A black box tester typically adopts the perspective of the customer and focuses on whether the future customer can successfully use the software. This means black box testers may use similar devices and mimic the behaviours of the future consumer. White box testing only focuses on the successful implementation of the software. Developers conduct evaluations from their own perspective and use all necessary internal tools to address coding errors, improving a program's overall capabilities.

Input and output vs. code pathways

In black box testing, a user typically performs a task to test if it achieves the desired outcome. In white box testing, an individual examines an aspect of a program's code to ensure each line works sequentially and has the correct value or type of data. Black box testing looks closely at the outcome of an event, while white box testing looks at the process to get that outcome.

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Short-term vs. long-term

Black box testing takes a shorter amount of time to execute compared to white box testing. When a person conducts a black box test, the developers determine the length of each evaluation because they only test features a company chooses. White box testing might involve an in-depth analysis of different sections in a program's code. It's a detailed process that may require a lot more time to complete.

Manual methods vs. automated trials

Black box testing often requires some coordination between testers and software developers. As black box testers discover problems with the outcome of a program, they may communicate with programmers to establish the location of the problem in the code. White box testers can often use automated software to test the functionality of their code and focus on problem areas when the automation identifies them. They may conduct manual tests to isolate certain errors in a section of code but more often use technology to accomplish their tasks.

Program evaluation vs. structural testing

Black box testing involves running software to evaluate its functionality and performance. A tester may explore a program's various features through different trials and log errors they encounter to ensure it's ready for future customers. White box testing requires an individual to analyze individual lines of a coding language to check for errors and determine ways to improve its features. If a black box test uncovers an error, you can use a white box testing procedure to determine which area of code potentially caused it.

Types of black box testing

Here are a few types of black box testing processes:

Functional testing

Functional black box testing only focuses on the function of the program and how well the system carries out its functions. It is not concerned with the operation of the program or any errors it may encounter during the process, so long as the function performs as it's intended. For example, a tester may review whether you can log in to a network using the correct identification.

Non-functional testing

This type of testing aims to establish which aspects of a program are not functional and how they relate to the overall readiness of the system. Testers carry out this type of testing after functional testing has pinpointed any errors in the program. Developers can then revise any errors and can send the program for regression testing.

Regression testing

After black box testers run their evaluation, they can send any errors back to the programmer for revision. Regression testing retests the program to ensure programmers resolved the errors and that the program is functional. If testers identify any errors, regression testing prevents them from being published in the final version of the program.

Types of white box testing

Here are a few types of white box testing processes:

Unit testing

Unit testing is often the first type of white box testing that programmers use. It consists of programmers testing each block of code as they develop it to catch any errors before they continue with the code. Unit testing catches most of the errors and stops faults from building up as the code progresses. Programmers may also perform it between other tests to check if new errors arise.

Static analysis

Programmers run this type of test to determine if each line of code is functional, meaning other lines of code can use its output to perform their functions. This type of testing focuses solely on each line of code instead of the overall functionality of the code. For example, if a source code contains the correct font size and type, it can show up in a program's text.

Statement coverage

Programmers use static testing to check the internal coding and infrastructure of a program to see if they generate the correct number of successful outputs. Programmers can check this value against the total number of outputs to see if any are non-functional. The value is formulaic and allows a developer to design the parameters for other white box test cases.

Benefits of white box testing

Here are some advantages of white box testing:

  • Optimizes a program's code: Programmers can use white box testing procedures to discover errors and make alterations. They can determine the best strategies for improving the functionality of the code and its performance.

  • Presents a clear evaluation structure: White box testing requires a defined framework and clear rules to work successfully. As a result, a project team can better predict when they can finish a testing process, allowing them to make more accurate product release plans.

  • Streamlines test process creation: A tester often creates evaluation scenarios directly after receiving a program's final specifications. Black box testing allows testers to discover errors quickly and make suggestions for the development team to revise and implement.

Benefits of black box testing

Consider the following advantages of black box testing:

  • Offers multiple perspectives: A tester may have different information about a program than a software programmer or engineer, so they can identify more areas of improvement. They may also primarily work in a different industry, meaning they can target a product's usability to various groups of people.

  • Improves a program's specifications: Black box testers can identify ambiguous wording in a program's requirements, which describe the features it has to achieve its intended purpose. If a project team clarifies these requirements, they can create more precise features.

  • Streamlines communications: As internal teams frequently use white box testing, they can establish communication patterns and relationships ahead of time. This may streamline communication, as there may be fewer questions, and all parties often operate in the same building.

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