Black Box Testing

By TestNBug in Manual Testing Basics 0 Comment
Black-Box-Testing

 

What does ‘Black Box Testing’ actually mean? Why is it required and its importance? let’s find out in this tutorial.

 

Black Box Testing:

It’s a method of software testing that examines the functionality of an application, without looking into its internal structures or workings (code or mechanism). Black box testing is done from the customer’s point of view with the help of specifications.

For example consider a door lock as shown in the below figure. we do not know how the internal mechanism in the lock works ?

 

Door lock

We only know only specific set of inputs :

1. Number of keys

2. Sequence of using numbers (like # to be used in the middle)

3. Direction of key (clockwise to lock and anti clock to open) after entering the PIN.

To use the lock one need not require any knowledge of how the internals of the system work. However, we need to understand the external functionality of the lock like : features of the lock, functions, inputs, expected output etc.Blackbox testing requires only the functional knowledge of the system under test. Hence, It is also known as functional or behavioral testing.

 

Login form
Similarly, for user login page what does the user need to know ?

1. Valid user name

2. valid password

3. Clicking on ‘Sign In’ should allow user to login .

4. If not a member , then ‘Sign up’.

Hence , Black box testing is more about the functionality of the application rather than the internal code . In this example, we are not worried about what happens in the back-end, what is the programming language used, what database etc.

From the black box testing point of view, we need certain inputs to test and the expected result. If the expected result matches the actual result, we call as ‘test case’ passed.

 

exhaustive testing is not possible

 

As we are testing the external functionality, there is a need to arrive at the set of test cases to test, to find many defects as possible. This may be a tough task, but the following ‘Black Box Testing Techniques‘ will make our life easier.

 

The various Black box testing techniques are :

  • Requirements based testing
  • Positive and negative testing
  • Boundary Value analysis
  • Decision Tables
  • Equivalence Partitioning
  • State Based testing
  • Compatibility testing
  • User documentation testing
  • Domain testing

These techniques are very much required for designing the test cases. We will discuss about these techniques in detail in the next posts. black box testing techniques part 1,BBT part 2)

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