What is Black Box Testing | Techniques & Examples

Black box testing is a very important type of testing in which the tester is not aware of the internal architecture of the software but rely on their black box testing techniques for the process, i.e.

• How has the code been written?
• Which algorithms have been followed?
• What is the workflow of the application?

The main focus of this testing is checking the capability of the software to meet the requirements. Because it doesn’t matter how the application has been built if it couldn’t satisfy the purpose of what the application has been built and is not convenient to operate by the user. 

No programming knowledge is necessary for performing this test, so anyone who is experienced enough to understand what to expect from the software of a certain type. Various Black Box Testing techniques are used to perform them efficiently. The techniques we will discuss in this article will help in:

• Finding the most effective test cases
• Reducing testing time without compromising efficiency
• Having large test coverage

Types of Black Box Testing Techniques

Below are the different types of Black Box testing techniques:

1. Equivalence Class Partitioning

Equivalence class partitioning is a technique in which the inputs are decided into certain groups. These groups are made based on the idea that the outcome of a test condition for input in the group will be the same for the entire group. By this, it can be implied that, if the test fails for one input then the test will also fail for the rest of the inputs in the group.

Similarly, if the test is successful for input in the group then it will be successful for the entire group. Since, this technique reduces the number of tests cases required to be performed, hence reduces the testing time. Along with that, provide good test coverage by covering several possible inputs in one run. 

When using advanced testing methods like equivalence class partitioning, a software test company ensures efficient testing and optimal outcomes.

2. State Transition

The state transition technique is used to perform the test cases that require various state transitions in the software. This technique is very effective in finding situations where the system produces different outputs for the same input. This inconsistency in the output depends upon the events that occurred in the earlier states.

An example of this type of system is an Automatic Teller Machine, in which a user can withdraw a certain amount of cash again and again until the daily limit is reached. This shows that even after giving the same input, the machine will produce a different result, either withdrawal will be successful or daily limit reached message will be displayed.

3. Decision Table

The decision table technique is also known to be the Cause-Effect table. This technique is followed to test the system that produces different outputs based on the combination of inputs provided. 

The functionalities have a logical relationship between input i.e. if-else conditions. Test cases in this technique are generated based on the condition and action. Here, the condition is inputs provided to the system and actions are the output generated by the system. 

For example, it should be ensured that the user is allowed to log in to an Email account only if both the user ID and password are the same.

4. Boundary Value Analysis

In Boundary Value Analysis, the system’s response on the boundary values of the partition is tested. In a certain system, there are situations that it works perfectly on all the values in the input partition except the boundary values. 

So it is necessary to make sure that these inputs are also covered. The maximum and minimum values of each partition are considered as it’s boundary values to test the software on. The boundary values for a valid partition are called valid boundary values. 

The boundary values for an invalid partition are called invalid boundary values. For example, if a text box can accept the text of 8 to 14 characters, then the boundary value analysis will be performed by entering text once of length 8 characters and then of length 14 characters, to check if it’s working perfectly just like for a text of length more than 8 or less than 14 characters.

5. Exploratory Testing

Exploratory testing is a different kind of testing technique that is performed without any specific plan. In this, the tester finds defects in the software by just exploring and learning the software without having any knowledge about the system requirements. 

The success of this test depends upon the quality of the tester. A good tester can use his experience to find imperfections in the application. The tester operates the software as per the wish and investigates using different inputs. It does not involve the creation of test cases, it’s the tester’s ability to think of the actions that can expose the loopholes in the system.

6. Error Guessing

Error Guessing is another testing technique that does not require any specific plan to find the bugs and defects in the software. The tester uses his prior experience to find the system’s weaknesses.

For example, submitting a form without entering any input or trying to input numerical data in the text box expected to store alphabetical data. The tester should know about what to expect from a system of a particular type, and the errors that can be present in it. Analysis of historical data and test results will make the testing more effective.

Tools Used for Black Box Testing

The Black Box testing can be performed both manually and by using automated tools. Automated tools can increase the rate of testing and accuracy. With the aid of automated tools, the execution of a test can be made agile. These tools record the test cases using some of the scripts like TSL, Visual Basic, JavaScript, Perl, etc.

Some of the tools available for performing black box testing automatically:

1. Appium

2. HP QTP

3. Selenium

4. Applitools

5. Microsoft Coded UI

Conclusion

Black Box testing techniques are very useful in evaluating the performance of the software, and the experience a user will have while using the software. These types of black-box testing techniques help in reducing the testing time, efforts and focusing on creating test cases that can evaluate the software functionality most effectively and efficiently.

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