What Is Blackbox Testing?

Black box testing is performed on a system to see how it responds to expected and unexpected commands. It also tests the system’s response time, reliability, and usability issues. The tester will usually add input and then observe the system’s output.

Remember that black box testing involves software without prior knowledge of the internal structure.

Black box testing is extremely powerful and reliable because it exercises a system with end-to-end results. The tester will try to simulate user activity in test cases and then see whether the system responds adequately.

There are various test cases, but black box testing usually tests on web servers, databases, dependencies, and integrated systems. To learn more about black box testing techniques and how they relate to software testing, continue reading ahead.

What Is The Difference Between Black Box And White Box Testing?

Contrary to popular belief, these aren’t two sides of the same coin. There are a lot of differences between the two. Here are some worth mentioning.

White box testing is often done simultaneously as black box testing. It differs from the latter as it involves testing an application after having complete information. The tester is aware of source codes, configurations, and even architecture.

White box testing can also expose security vulnerabilities, data flow issues, and broken paths in the internal structure. Compared with black box testing, the white box provides more comprehensive tests.

Types Of Black Box Testing

Black box testing is applied to three different types of tests. Here is all you need to know about them:

Functional Testing

Functional testing allows testers to focus on the most important aspects of software, thus identifying critical errors. It also checks to ensure that it is possible to log in with correct credentials and not get in with incorrect ones. Some examples of functional testing include:

Smoke Testing

This is done to test critical aspects of the software.

Integration Testing

This is done to see the integration between important components.

System Testing

This is done to check for errors in the whole system.

Non-Functional Testing

Both functional and non-functional types of black box tests relate to software testing. A functional test sees if the software can perform a specific action, and non-functional testing sees how a specific action is performed. Through this type, you can check for features beyond the common functionality of the software. The tester can assess whether the software is:

  • User-friendly and easily understandable by the user.
  • Performs under peak loads.
  • Vulnerable to security threats.
  • Compatible with operating systems, browsers, and different screen sizes.

Regression Testing

This black box test is done to see whether the new versions of a particular software show degradation, regression, or are capable of both.

The good thing about regression testing is that it can test both functional and non-functional aspects of particular software.

How Is Black Box Testing Done?

While you need professional help for black box testing, knowing how it is done is useful. Here are some general steps that all testers follow when they make black box test cases:

  1. The system is examined to see all the requirements and specifications needed for testing.
  2. The tester chooses valid and invalid inputs to see whether they are processed accurately.
  3. The tester also determines the right outputs for the inputs. This helps them compare expected results with the achieved results.
  4. Next, the tester will create test cases to assess some more inputs. The test cases are then executed and results generated.
  5. Defects are identified.

What Are The Most Common Black Box Testing Techniques?

To adequately test systems, test cases need to be prepared by professionals. Here are the most common black box testing techniques used to create these test cases:

Equivalence Partitioning

Equivalence partitioning is also known as equivalence class partitioning. When creating test cases using this technique, the system’s or your application’s input values will be divided into different classes or groups.

This division is done based on the similarities of the outcome. This technique requires less time and effort because now, instead of testing every input of every group, the tester will only have to test one input value from each group. If the results are positive, the tester won’t have to deal with all test cases and can move on to the other group quickly.

Boundary Value Analysis

Many applications face issues with values on the boundaries. Boundary refers to specific values that are present at the extreme ends. Since they are close to the limits, they determine when the system’s behavior changes. This technique hence focuses on values at boundaries. This technique includes both valid and invalid inputs in test cases to verify the main issue.

For instance, if you want to test a field where values range from 1 to 100, you will test boundaries that are close to either 1 or 100. In this case, you will use 2, 99, or even 101 and -1. Both valid and invalid values are added to generate a complete result.

Decision Table Testing

This technique is used in test cases where logical relationships exist. Any relationship with action 1 (condition=true) will determine action 2 (condition=false). The tester will start by identifying two outputs, like action 1 and action 2, for two conditions (either true or false). Next, a specific decision table is created to test different scenarios and the responses they generate.

State Transition Testing

This technique of black box testing is used where different states of the same system need to be tested. The system’s state will keep changing depending on external events or conditions. These outside scenarios trigger a change in the system’s state, which the tester will scrutinize.

There are two ways to do this: the tester can make a systematic state transition diagram or a complex one. Depending on the intensity and frequency of change, the tester makes this choice.

Error Guessing

Also known as experience-based testing, this technique will require the tester to use his profound experience to test the functionalities and application behavior and identify all the areas prone to errors. Any good developer will be able to find common errors found in systems.

Some common mistakes developers can forget during the creation of programs include division by zero and handling of null values in text fields file uploads without attachments. These are identified using the error guessing technique.

Graph-Based Testing

As the name suggests, a graph is prepared to test different objects. Since all objects are made of a set of objects, pictorial representation is helpful and makes it easy for the test to find unique errors. The relationship between the objects in your test cases is drawn using this object graph. The results are then written accordingly.

Comparison Testing

Last, this black box testing mechanism is simple and uses independent versions of the same program or software to see which works better.

Benefits Of Black Box Testing

A black box test is a software testing method that is reliable and efficient. Here are some benefits to using a black box test:

  • Testers are not required to have expert programming skills or advanced technical knowledge.
  • Testers are not required to learn implementation details or the internal workings of a system.
  • There is a very low chance of false positives.
  • Allows for both functional tests and non-functional tests.


What Is Gray Box Testing?

Gray box testing is the middle ground between black box and white box testing. Where the former gives the tester no insight into the system and the latter complete insight, gray box testing tries to achieve a compromise between the two. It gives testers partial and incomplete knowledge of the system to test environments and their effects on applications and systems.

The most common use of gray box testing includes end-to-end system testing, penetration testing, and integration testing.

Why Is Software Testing Important?

Software development requires finesse. This is why the development team goes an extra length to check for bugs or errors before delivering the software. Through a black box test, the company can ensure that the system’s functional and non-functional requirements are met.

Final Words

Black box testing is usually done during software development to see if the test cases generate the correct output. The test designer selects objects in a software system and performs various black box tests.

Through unit testing and boundary value analysis, the tester compares the actual output with the expected output to see how well the system works. So if you want to check the system’s functionality, you may want to try black box testing techniques.

Derik Belair

As President and CEO, Derik leads the vision, strategy and growth of Augmentt. Prior to founding Augmentt, Derik was the Vice President at SolarWinds, leading the digital marketing strategy for SolarWinds’ Cloud division. Derik has been working in the channel for over 20 years, starting his career as a channel sales rep at Corel Corp. and eventually becoming the first employee at N-able Technologies in April of 2000.
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