What is Black Box Testing?

Black Box testing is a testing technique in which the functionality of the system is tested without looking at the code structure of the applications under test. The name of this technique comes from here, we have a black box and we cannot see the structure inside unless we open it and look. The tester cannot see the code structure of the application under test and is often unaware of the architecture of the code. The Black Box test method is based on validation of the results obtained after applying various inputs to the application under test with expected system outputs.

We mentioned the software testing processes in an article in the blog page. This technique can be a part of 5th step of processes chart.

Black Box testing techniques can be generated from requirements documents or design specifications. So testing can start right after the requirements are out. With Black Box testing method, we can test any system such as Linux, Website, Database or our own applications. Our aim is not to focus on the functionality of the code, but only on the inputs and outputs, and in this way, we can use our time more efficiently.

Now let’s talk about Black Box software testing techniques.

What are Black Box Testing Techniques?

Boundry Value Testing

In this technique, the behavior of the applications under test is tested at the boundary values. When checking a value range, after selecting a section that is valid for our system, the behavior of the current sections of the program at the limit values ​​is checked.

To give a simple example,

Let’s say we have a system with a lower limit of 1 and an upper limit of 10 people, (if 1<x<10)

For this we should test our system with lower bound [1,2] upper bound [9,10] for valid range, and lower bound[0], upper bound [11] for invalid range.

Equivalance Partitioning Testing

The purpose of the equivalence classification testing technique is to eliminate sets of input data that make the system behave in the same way and produce the same result when testing a system. Our aim is not to perform the test repeatedly for the inputs that we will get the same result because of the time constraint. The equivalence classification test enables the dataset that gives the same result when executing a program to be defined as an input condition and classify them as an equivalent dataset. If we classify on the basis of the above example, we create clusters such that a value between [1–10] within the valid range, a value from the range for values ​​less than 1, entering a negative value, and a value for values ​​greater than 10, and determine the test entries.

State Transition Testing

In such tests, the system will treat all test input variations within a partition in the same way. If the system passes one of the entry conditions, it also passes all the other entry conditions in the section. If it fails one of the entry conditions, it fails all the other conditions within the partition.

Decision Table Testing

It is a software testing technique used to test system behaviors with different combinations of inputs. This is a schematic approach where different combinations of inputs and their corresponding system behavior are shown in tabular form. It is also called a cause-and-effect table because it shows cause and effect.

What are the Black Box Test Types?

We will discuss each of the Black Box test types in detail in our upcoming articles. But now we would like to talk briefly.

Functional Black Box Testing

This black box testing technique is related to the functional requirements of the system. Software is written in modules and components. It is a test to make sure that the modules that make up a whole system work as expected. We can give an example like this, we have a module that performs currency conversions, simply our test entries should be like this.

1- Decimal number

2- Positive number

3- Negative number

4- Zero

5- An empty entry

6- A value that is not a number

It can be seen from the above input values ​​that 4 inputs should be valid and the last 2 inputs should give an error message. Tests performed in this way are called functional tests.

Nonfunctional Black Box Testing

In this test method, the quality of the software to be tested is usually checked. Quality depends on the time, accuracy, stability and durability of a product under various adverse conditions. In fact, they are tests made to ensure that the developed software works smoothly and efficiently in all conditions according to the expectations of the user.

Regression Testing

This type of testing is to ensure that if we make changes to the software anywhere during software development, it doesn’t unexpectedly affect other parts of the system.