Software Test Design Techniques: What are Black Box and White Box Tests?

We can consider software test design techniques under two headings as Black Box and White Box tests. In this blog, we have compiled the subcategories of test design techniques by summarizing the advantages, disadvantages and how they are performed.

What are Black Box Tests?

Black Box Testing from software test design techniques; It is a test technique that is used to measure the functionality of the system without knowing the internal structure of the software, that is, without looking at the code. It can be applied without having knowledge of the architectural structure or source code, by seeing the related system as a black box. The purpose of black box tests is to measure whether outputs that meet the requirements are received. Outputs that we do not expect should be tested as well as the outputs we expect to receive from the system.

This test design technique is one that testers often use. Black box testing; It can be used at all levels of testing such as unit, integration, system and user acceptance testing. Black box testing technique has advantages as well as disadvantages. Let’s examine the advantages and disadvantages.

Advantages of Black Box Tests:

• No code knowledge is needed as it is made by testers.
• Since the developer and tester of the code are different, it can be tested from different perspectives and even invisible errors can be found easily.
• Tests can be administered quickly and effectively.
• Test scenarios can be created right after the requirements are determined.
• When this method is used in large-scale systems, very high efficiency is obtained.

Disadvantages of Black Box Tests

• Since the internal structure of the system is not known, it becomes difficult to find clustered errors in the source code.
• It can be repeated by the developer’s own tests already.
• Cannot be used in software containing complex code blocks.
• It is not possible to check all possibilities, so there may be untested functions.

7 Different Black Box Test Techniques

1. Equivalence Division Design

It can also be called the equivalence fractionation test technique. In its simplest definition, it is grouping test conditions that have the same characteristics and testing applications, with a limited data set selected from each of the determined groups.

2. Boundary Value Technique Design

It is a boundary value technique. It is the tests done by checking the lower and upper limits of the variable instead of focusing on a single point in the software to find the errors in the software. Furthermore, it is used because the probability of error in the limit values of the software is slightly higher.

3. Decision Table Test Design

It is a decision table testing technique. It is used for multi-condition complex software with specified requirements. The business rules are written on a table, and the values that can be taken for the inputs and which output can be taken for which input are shown in this table. All possible test scenarios are written in this table.

4. Classification Tree Test Design

Classification tree is a test design technique. It is a technique that models the object used for testing in a tree view of hierarchical equivalence shares and generates test scenarios based on the relations of these shares with each other.

5. Paired Test Design Technique

It is a paired test design technique. It is a testing technique that significantly reduces the number of test scenarios in cases where the function of the software being tested has more than one combination. Rather than scenarios where one input and one output are entered, two inputs increase error detectability. This technique saves a lot of time.

6. State Transition Test Design Technique

It is a state transition test design technique. It is done by evaluating the past and current conditions of the software. Transitions between states are tested. Successful transitions and unsuccessful transitions are plotted into a diagram. It is a technique often used on embedded or electro-mechanical systems.

7. Use Case Test Design Technique

In this technique, a test scenario is produced using functional and non-functional requirements. The most important feature of this technique is that the scenarios are clear and detailed. Basically, the test method measures a user and whether the situations that this user expects from the system occur.

What is White Box Testing?

One of the software test design techniques, White Box Testing, can also be called transparent box testing. Just like its name, it is a technique in which test scenarios are designed by knowing and measuring the internal structure of the software’s code by looking through a white box. The main purpose of this method is to test the code snippets one by one and see that they can be run in a healthy way even in the smallest particle. It is tested whether the inputs determined as a result of the requirements meet the outputs in a part of the code. The functionality of the software is not tested.

It is mostly used by software developers as well as by software testers. This method is used at the unit, integration, and walk test levels. When we examine the advantages and disadvantages of the white box testing technique;

Advantages of White Box Tests

• Since the tests are designed and made while the software is being developed, it can be intervened early.
• The reliability of the code is high as the developers review their code snippets many times.
• Code optimization is more.

Disadvantages of White Box Tests

• Finding a qualified software tester who knows how to read code is difficult and costly.
• There may be points that may be overlooked because the developer does his own testing.
• Tests can take a long time because they are very comprehensive and detailed.

2 Different White Box Test Design Techniques

1. Command Test Design Technique

A command is a function that we want to perform directly in the code. Int y=5 is a command. Command test design, on the other hand, is achieved by going through all the commands in the software at least once and testing all of them.

2. Decision Test Design Technique

Decision scope is the decision points in our code that can generate more than one result, such as if else, while, switch. In this test design technique, the cases where the decision points are passed over each condition once are evaluated. Decision points must be passed over.