Test Design Techniques You Need to Know

test design techniquesBusiness software development is getting very complex these days due to the constant change in technology and tight schedules. If you want to ensure that your software is delivered with top notch quality, then it is essential to implement some of the effective test design techniques. The purpose of test design techniques is to test the functionalities and features through some effective test cases. It is a better option to use these test designs based on the kind of software you are building rather than picking the test designs out of the air. Generally, software systems have a high level description along with some informational representations. The purpose of this tutorial is to provide guidelines for implementing effective test design techniques for testing your business software that needs to be implemented across different applications of varying complexity. Before going into the details of test design techniques, let’s briefly discuss about software testing in general.

Software Testing

Software testing is the process of identifying the correctness and quality of any software. This includes the process of executing the software with the intent of finding errors. From the developer’s point of view, software testing is performed to determine if the designed software meets the specifications. From the view of a business owner, software testing is performed to determine if the software meets the operational needs of the business. Our course on software testing will help your team learn how to plan, design and execute tests in different environments. A number of factors are considered for effective test design techniques such as accuracy, traceability, completeness and testability. You can use the below approach for an effective test design: 1. You should first gather and understand the requirements of your clients 2. Derive all the business scenarios that you find to be important 3. Design an appropriate test scenario for the business scenarios that you derived in the above step 4. Particularize the test scenarios to build different test cases For example, if you’re building a mobile app, you need to cover all the scenarios an end user may get into with your app. This calls for both an effective mobile app design (like in this course), and an effective mobile app testing strategy. This course helps explain software testing strategies, specifically for mobile apps.

Test Design Techniques

To get it right within the lifecycle of any software development, accurate and complete information are the essential elements. They ensure that your products meet the expectations of your business and customers by enabling the test team to work in a systematic manner. Effective testing goes hand in hand with the process of analysing the requirements from your business viewpoint. The ambiguity testing technique is one of the best testing design techniques that identify the accuracy completeness of the information. This testing technique helps developers to eliminate defects in the requirement phase of the software development life cycle. This kind of approach prevents defects from spreading to the other stages of software development.

You can learn more about test driven software development in this course. Though the course talks about Java development, the principles hold good for any kind of software development.

If you want to develop a business product of the best quality, you need to implement effective testing techniques after understanding the requirements of your business. At this stage, you need to design a perfect business scenario where you need to draft the requirements as per the sequence of actions to be performed on the product. The actual business flow of the product is included in the business scenario. It is recommended to have the business scenarios signed off to make sure that the desired functionality is completely covered. Find out more on test design techniques in our course on effective software testing techniques .

Categories of Test Design Techniques

Test design techniques can be defined as high level verification steps that are created to design a product or software that is free from all kinds of defects. Test design techniques can be derived from business scenarios and are categorized based on the type of testing. Based on the criticality of your business scenario, test design techniques are prioritized into low, medium and high. The test design techniques allow the developers to execute the tests based on the risk factor. If you are programmer, or manager, our Agile Testing training course will help you master the process of software testing. Below are some of the test design techniques that most development companies use:

Black-Box Test Design Technique

This technique is also called specification-based test design technique and uses external descriptions of the software such as technical specifications, design, requirements of the customers etc. Even if the tester doesn’t have any knowledge of the code of software or internal structure, he/she can perform the test using the following popular methods:

  1. Boundary value analysis – This is the best test design technique wherein the developer tests the input values at the boundaries. The input values are tested at the initial stages because there is a significant chance of causing errors in the functionality of the system if the input values are recognized at extreme ends. The boundary values include – minimum, maximum, error values and inside/outside boundaries.
  2. Decision table testing – This is used to identify the condition of the test based on the decision tables that are associated with different conditions. Each and every decision corresponds to a relation, variable or predicate. Many decision tables include the symbol ‘hyphen’ means ‘don’t cares’, which mean the decision tables have little influence on the actions that are being performed. The main advantage of using this technique is that it provides great confidence of the test cases.
  3. State transition testing – It’s used to identify the conditions of the test from a state table. The state table can be considered as a truth table, wherein some inputs represent the current state, while other inputs represent the next state. This test design technique is appropriate for applications that have implemented workflow within them. Find out more about black-box testing in our course on Software Testing.
  4. Equivalence class partitioning – This test design is designed with the purpose of reducing the number of tests by dividing the different tests. After division, the system will behave in the same way for all the tests with equivalence partition. The test inputs are selected on the basis of each equivalence partition.
  5. Use case testing –This method is used to derive the test condition from the use case. The test conditions derived from this technique are end to end business cases. In this kind of testing, the test cases are designed to execute business scenarios and user-end functionalities.

White-Box Test Design Technique

These techniques are based on the internal structure of the program and software code, going into the minute details of the developed code and testing them one by one. Here, the tester should have proper knowledge of coding and internal structure.

  1. Condition coverage – A major percentage of the outcomes of test conditions are exercised by this technique. Condition testing is a white box test design technique, wherein the test cases are designed in such a way that the condition outcomes are executed.
  2. Decision coverage – Here the test design technique exercises the percentage of the outcome of the decisions and designed in such a way that decision outcomes are executed.
  3. Statement coverage – This technique is involved in calculating the percentage of executable statements that are being exercised by the test suite.

Experience Based Test Design Technique

This kind of test design technique is not involved with internal and external structure, but is based on experience. The following methods of testing are can be adopted:

  1. Exploratory testing –Used to test the applications without any test case documentation, it is usually conducted by a business analyst and other business experts
  2. Fault attack – This is one of the widely used techniques in experience based testing wherein the testers are allowed to anticipate the errors based on their experience, availability of the defect data and common knowledge on why a product normally fails.

While writing a test for a business scenario, it is advisable to keep the following points in mind:

  • To attain 100% logical coverage, it is advised to use decision test design technique
  • If you want to cover a broad array of inputs, you can use boundary value analysis and equivalence partitioning
  • For field level validations, combinations and permutations may be used

The above test design techniques help testers to select a good set of tests based on the number of possible tests for any given product. All the above test design techniques have their own strength and weakness. Each individual technique is good at finding certain kinds of defects, whereas poor at finding others. However, you must choose the best set of test design techniques to achieve maximum coverage. With the right combination of all the above techniques, you will surely be able to discover the best test scenario for all your testing requirements.