Black Box vs. White Box Testing: Understanding The Differences

If you want an edge over competition in the software market, you must test your products for vulnerabilities and bugs. Automated testing, black box testing, and white box testing are all essential tools your business can use to ensure software and systems run as they should and are of guaranteed quality.

There are several kinds of white box and black box testing, and each general testing category has its uses. Misusing them can return incomplete results, but using them correctly will help you improve your software. 

Before you choose a testing method, you need to understand why and when to use them. Here’s what you need to know about black box vs. white box testing. 

⬛️ What Is Black Box Testing?

You can’t see inside a black box. That’s the point of a black box test. 

Black box testing methods let you test a system without knowing how it works internally. It doesn’t require any programming knowledge. 

A test provider provides the input and then watches the output produced by the system. The purpose is to see how the system responds to user actions that are both expected and unexpected. Additionally, black box testing reveals:

• Usability issues
• Reliability issues
• Response time

Black box testing techniques are effective for comprehending a system’s function from start to finish without knowledge of its architecture or coding. All subsystems, such as web servers, application servers, integrated systems, and databases, undergo testing.

🔑 Key Characteristics and Principles of Black Box Testing

There are several key characteristics of black box testing. 

• The tester has no knowledge of the internal structure of the software system
• The test is based on specifications
• The test focuses on functionality against the required specifications

Black box testing helps determine if, when, or why a problem happens through functional testing, nonfunctional testing, and regression testing. It looks at input and output only. This is in contrast to white box testing, which determines only why a problem happens. 

Black box testing can be performed by individuals or teams and doesn’t require a deep understanding of code or a system’s architecture. It is less time-consuming, and it’s possible to use black box testing for random testing and error guessing, boundary value analysis, and equivalence partitioning. 

⬜️ What Is White Box Testing?

White box testing lets testers verify and test a system’s inner workings, including:

• Coding
• Infrastructure
• External system integrations

White box testing is common in the Continuous Integration and Continuous Delivery (CI/CD) development pipeline. It is often used with automated build processes. You may come across it in the context of Static Application Security Testing (SAST), which involves reviewing source codes and binaries to identify potential vulnerabilities and bugs.

There are several methods of testing, including:

• Static code analysis, a type of code-based testing that identifies coding errors and vulnerabilities in static code
• Mutation testing, which looks for consistency of code and makes small changes to see if the code can still pass the test
• White box penetration testing, during which an ethical hacker attempts to attack the app based on knowledge of the software’s internal workings
• Unit testing, which includes tests that are part of the application code
• Integration testing, which looks at integration points between internal components or external systems

White box testing requires a much deeper look into your software and its “inner workings” — it figures out why a problem is occurring within scripts or the software’s coding.

🔑 Key Characteristics and Principles of White Box Testing

White box testing is a more precise kind of testing that allows you to verify your software’s code, integrations, and infrastructure — it requires specialized coding knowledge to get started. 

White box testing doesn’t just look at inputs and outputs. It also considers how the inner workings of code influence everything between the time a test case is input and the output is received. 

White box testing has some notable benefits:

• Covers all aspects of a piece of software’s code
• Reduces communication overhead between developers and testers
• Allows you to focus on improving your code and developing a quality piece of software

↔ Differences Between Black Box and White Box Testing

There are a few key differences between black box and white box testing. White box testing helps you look at structural issues with your coding and can find hidden issues and bugs that make the components of a piece of software function incorrectly. 

Black box testing ensures the entire system works as it should, approaching the test to look only at the output rather than the process of getting to that output. 

Knowledge of the Internal Structure

The first difference is that you don’t need knowledge of the inner workings of the software or system if you use black box testing. If you do white box testing, you’ll be looking at coding and infrastructure directly. 

Focus of Testing

Black box testing is performed on any software program. Three levels of testing are possible:

1. Functional testing: Testing that specifies if certain features will perform with given inputs
2. Nonfunctional testing: Testing that determines how certain features perform with given inputs
3. Regression testing: Testing that shows how a product changes from an older to a newer version (can be used with functional and nonfunctional testing)

White box testing has a different focus on the functionality of the software. It looks at the code and is normally performed before software releases to ensure it’s free of bugs. 

The test also cannot look at expected functionality for functions that aren’t directly in the coding. Essentially, white box testing cannot perform a test from a user’s perspective. Black box testing is a user experience testing approach.

Effort Required

The amount of effort required varies based on the kind of test, too. You don’t need coding knowledge for a black box test, so anyone can perform the test. White box testing does require knowledge of coding and more intensive training. You must work with someone who understands code and be cautious about making changes. 

Black box testing is behavioral testing, meaning you only look at the output. White box testing looks at all aspects of a system, which means you’ll spend more time on the testing process. 

It is also much harder to automate white box testing than black box testing. 

Effectiveness

The effectiveness of each type of testing is different. White box testing is more “surgical,” meaning it provides more specific data. Black box testing is less precise. 

White box testing is used to find all hidden errors internally, so it can have an advantage over black box testing, which only looks at the software’s responses to stimuli. Both tests are necessary to produce software that runs as expected. 

⏳ When To Use Black Box and White Box Testing

Black box and white box testing have different purposes, so your testing technique will vary based on your goals. You can use black box testing for all tests that don’t require an intensive understanding of coding or the data patterns within the software. Black box tests are not as in-depth as white box tests, so you need white box testing to better understand the vulnerabilities or bugs. Another important distinction is that black box testing isn’t used for algorithms (white box testing is). 

Software Development Lifecycle Differences

In software development, testing can be performed during two kinds of life cycles. The first is the systems development life cycle, which includes the following stages:

• Planning
• Coding 
• Testing
• Deployment

The software testing life cycle is different. It includes multiple testing stages:

• Test planning
• Test case development
• Test execution
• Test closure

White box testing is a necessity during the coding and testing phases. It can also be used for security testing or structural testing. On the other hand, you’ll often use black box testing for system and acceptance testing. Since it’s less specific and requires no coding knowledge, you’d only want to use it to check the software’s features and how they function.

Get the Black Box Testing Tools You Need for Testing Automation

Black and white box testing have their purposes, and you may need to do both. When you’re troubleshooting and need general answers without deep knowledge of the underlying code, it’s black box testing you need to turn to. 

Ranorex can help. We provide the solutions, so you can focus on black box testing, unit testing, integration tests, and more to make sure your software is working as it should. Contact us today.