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Black Box Testing

Software testing depends on various types of techniques. They may or may not require
the knowledge of internal logic and coding of the software. Black box testing is the one in
which the focus is on validating the output generated from the software after it is fed
with an input data set.

What is Black Box Testing?

The black box testing is the testing type in which the tester is unaware of internal
working of the software and focuses mainly on verifying if its features and functionalities
are as per the user requirements.

Different Types of Black Box Testing

The different types of black box testing are listed below −

Functional Testing

It is a type of testing done to verify if every software functionalities are working as per
expectations. It is not dependent on the code on which the software is developed. A set
of inputs are passed and outputs generated are compared to verify the functionalities. It
can be done manually or by automation.

Regression Testing

It is a type of testing done to verify if any code changes have not introduced new bugs in
the software.

Read More: Regression Testing

Non-functional Testing

It is a type of testing done to verify if the non-functional requirements of the software

are working as expected. It tests if it is usable, scalable, secure, robust, responsive, and
stable enough to be shipped to the customers.

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Advantages of Black Box Testing

The advantages of black box testing are listed below −

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The testers do not require programming and technical skills to start working on
the black box testing.

It is effective in adopting black box testing in large systems.

Every test conducted here is done from the customer’s perspective.

Tests are easy to replicate in the software.

It helps to detect ambiguous and incorrect requirements while doing a black box
testing.

Disadvantages of Black Box Testing

The disadvantages of black box testing are listed below −

The similar tests may be repeated while performing black box testing.

It is not possible to create test cases with incomplete requirements.

It is not easy to carry out black box testing with multiple sets of input data at the
various testing stages.

It is not possible to detect the root cause of a defect.

The intermediate stages of the software go untested.

It is time consuming to perform black box testing with large chunks of data.

Difference Between Black Box and White Box Testing

Sr.No Black Box Testing White Box Testing

The internal working of the software is The internal working of the software
1
not known to the testers. is known to the testers.

It only deals with the inputs fed to the It deals with the independent code
2 software and the outputs generated snippets, algorithms, methods,
from them. functions etc.

It only verifies the software

It verifies the internal working of the
3 functionalities and if they are working
software.
as per the user requirements.

It does not require technical skills and It requires technical skills and
4 programming knowledge of the programming knowledge of the
testers. testers.

5 It uses methods like equivalence It uses methods like statement

partitioning, boundary value analysis, coverage, boundary value analysis,

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error guessing etc. data flow, control flow etc.

It mainly focuses on the unit,

It mainly focuses on the functional
6 integration, and system level testing
periphery of the software.
of the software.

What is Gray Box Testing?

The gray box testing is the one which is an amalgamation of the black and white box
testing. In this technique, the testers are aware of the internal structure of the software
to some extent. They use the algorithms and logic used in the code to create the test
cases. It mainly detects context driven errors.

Thus the gray box testing uses the benefits of both the black box and white testing
techniques. It takes the inputs from both the developers and testers which help in
enhancing the overall quality of the software.

How to Perform the Black Box Testing?

The black box testing can be done using the below ways −

Syntax-Driven Testing

It is applied to a software which can be syntactically described with some language.

Equivalence class Partitioning

It is observed that multiple inputs yield similar results while they are fed to a software.
In such a situation, instead of providing all the alike inputs, a range of data which
generates the same outcomes are grouped together, such that only a single data within
that group is sufficient to test the software. Thus the input data are segregated into
various equivalent classes and then verified.

Let us take an example of an application which only accepts positive numbers. The input
data can be divided into set segments - valid and invalid. The example of an input data
within a valid range from 0 to 100, is 50, and data in the invalid range is any negative
number, say -2.

Boundary Value Analysis

It is seen that boundary values in a range have higher probability of finding errors. The
test cases created to verify the boundary values make them very effective and increase
the probability of detecting bugs in the software.

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Let us take an example of an application, which accepts the age of children from 1 to 5
years range. The test data should include the invalid data as 0 and 5.1, and valid data as
3.

Cause Effect Graphing

This is used to create relationships between inputs and outputs generated by the
software. The inputs are also called as the causes and the effect is the outputs generated
by feeding those inputs. The causes and effects can be converted to boolean graphs. The
steps to create test cases from cause effect graph are listed below −

Consider all the causes which are identified as the inputs and effects which are
identified as the outputs.

Create a cause effect graph from step1.

Convert the graph to a decision table.

Concert the decision table to a test case.

Requirement Based Testing

This is done to verify the requirements specified for the software.

Compatibility Testing

This is done not only to verify the software but also to validate configurations and
infrastructures needed to run it. In case of any modifications in the infrastructures, the
software should continue working as expected. For example, if the firmware of the
software is updated, there should not be any impact on its functionalities.

Different Black Box Testing Tools

The different black box testing tools are listed below −

Selenium − It is an automation tool used for web testing.

Appium − It is an automation tool based on Selenium.

UFT − It is a licensed automation tool.

Which Errors are Detected using Black Box Testing?

The below errors are detected using the black box testing −

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It identifies incorrect, missing functionalities and GUI errors.

It detects errors at the database.

It identifies the non-functional errors in the software.

Features of Black Box Testing

The features of black box testing are listed below −

It is performed by testers who do not have knowledge on the internal structure of

the software. Hence they have an unbiased approach towards testing.
It is done with respect to the software requirements and from the end users
perspective.

It is mostly focused on the external characteristics of the software and not in its
intermediate steps.

It is solely performed with the help of requirements hence it ensures maximum

test coverage.

It includes functional, non-functional, regression, and other testing techniques.

These test cases can be converted into automation thereby reducing time of
execution.

It does not require the programming knowledge of testers.

Conclusion
This concludes our comprehensive take on the tutorial on Software Black box Testing.
We’ve started with describing what is black box testing, what are the different types of
black box testing, advantages and disadvantages of black box testing, what are the
differences between black box and white box testing, what is gray box testing, how to
perform the black box testing, what are the different black box testing tools, which
errors are detected using black box testing and what are features of black box testing.

This equips you with in-depth knowledge of Software Black box Testing. It is wise to keep
practicing what you’ve learned and exploring others relevant to Software Testing to
deepen your understanding and expand your horizons.

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