What Is Test Design : Tools and Best Practices

OVERVIEW

Test design tools help testers identify and specify test cases by covering all aspects of a software product. Using them at the beginning of the test-design phase can produce effective test cases. Test design tools include features like studying and analyzing specifications and requirements to accomplish different tasks, like designing and creating high-level test cases, creating test input, and more.

When an application is sent to the testing team by the developers, it is not considered a “completely developed” application. By “completely developed,” we refer to an application ready to be shipped to the end user.

But since the testing team may find defects in the app, it may need to be sent back for a little more development or code trimming from a few places. It ultimately becomes the testing team’s responsibility to stamp an application as “defect proof.” This is a lot harder than it sounds because of the complexities of code and the time constraints we face during the testing phase.

To tackle such problems, the organizations came up with the idea of test design and using it to create test cases that are more meaningful and efficient than manual work. If we go the manual path, we are stuck in the same hardships of reading the code and writing test cases based on it.

Instead, we use tools designed specifically for these tasks and are popularly known as test design tools.

What is Test design?

To understand the effect of test design tools on the testing phase, we should know about the concept that lies in the core of their work, i.e., test design.

Let’s consider this logic diagram (which is not the only way or a standard to depict a test design but works for us now).

Bottom Up methodology

The above logic diagram of a test design is based on the state transition technique, which we will explore sometime later. Following are a few things you can fetch by observing the above logic diagram.

  • It is not a linear or a single scenario, i.e., you may see more than one scenario an end-user might face while interacting with this application.
  • Outcomes are clearly defined, which means you can guess what you will see when providing a specific action on the application.
  • Application may travel through six stages that may or may not be traversed in a single go.
  • Conditions are laid down for passwords, i.e., three attempts are given before blocking the user.
  • Transitions are provided, which means what you can expect from the application when providing a specific action at some stage.

Along with these, there may be more observations for you as a tester. Instead of providing the tester with the logic diagram, let's have a conversation where we verbally discuss the application's behaviors, actions, stages, and outcomes. Which of the following do you think would help the tester more in writing effective test cases?

A test case design is a design that helps you in writing test cases by looking at the design, observing the logic diagram, and writing the test cases. The result of this is that it speeds up the process as the parameters and the flow of the application is extremely clear to a tester.

Test designs depend on the type of test cases the tester wants to write. For example, the above test design is specific to a state transition. This means as a tester, you won’t be able to figure out the input types, input values, input constraints, etc., except knowing the stages the application flows in and the outcome you receive. So, this will result only in state-dependent test cases. To increase diversity, divide test designs into various segments.

Test design techniques

A tester tests an application from many corners rather than moving linearly in one methodology. Different methodologies target different behavior of applications helping uncover different types of bugs. To achieve that, start with partitioning test designs and help organize the test cases that come beneath them.

Following are the different types of test design techniques.

State transition test design

The first type of test design technique is the state transition test design, which relates to the theory of automation. The theory describes a general machine design that satisfies the current requirements with any type of input. When working on software, the requirement is what your application is serving. For instance, for a calculator application, uploading images is not a requirement.

In the state transition system, define states as the current stage you are on in an application. For example, if you are currently on the Login screen, term it “login state.” From this state, travel to other states or be in the same state depending on the type of input you receive. For the login screen, inputting the correct credentials will move you to the “dashboard state.” If you don’t, you will still be in the login state with an error message.

Ideology behind state transition test design - Errors occur while transitioning from one application state to another.

A state transition diagram may look as follows:

Bottom Up methodology

A state transition test design helps us visualize the inputs and expected outputs of the application under test, as discussed in the previous section. It can help explore whether you end up in the desired state after the input or if the application behaves abruptly.

Equivalent class test design

Equivalent class test design is the most suitable test design when the application has to be tested for extensive data and performing it manually is not an option.

As the name goes, the equivalent class test design divides the data into equal (not necessary, though) classes. The data belonging to each class are similar in any way. After this, select random values from each class and test the application with them. If the output seems expected, clear the class completely as a success based on the selected data. However, this does not mean each piece of data will be successful, but since they are similar, the probability of that case is lower.

Ideology behind equivalent class test design - Similar values may prohibit similar errors.

An equivalence class test design can be made as a table with output defined as follows:


Class Range Output
Infant 0-1 Infant not allowed
Children 2-12 Children not allowed
Adolescent 13-18 Success Sign Up
Adult 19-200 Success Sign Up
Invalid >200 Not valid age

The above table represents classes based on age.

Boundary value analysis test design

A special case of equivalent class test design is boundary value analysis test design. It needs special attention because of the high probability of errors occurring on a class's boundary values. This happens for many reasons, like not making any unique conditional statements in the code about corner cases or making code for generic values.

Boundary value analysis test design plays an essential role in testing because boundaries separate logic from being right and wrong. For instance, for the “age” class, if you just want to sign up adolescents, the most important thing is to check whether 12 is taken as a success. If 12 is considered a success and the requirement was for 13-18, the whole module of signing up breaks down. A similar thing could happen on the other end.

The ideology behind boundary value analysis test design - A lot of errors occur when we input boundary values.

Boundary value analysis is simple to perform. Just pick values closer to boundaries (even if that’s out of scope) and check the output of the application. For a system considering just numbers from 10 to 20, boundary values could be the following:

  • 10
  • 9.99
  • 9
  • 9.09
  • 10.01
  • 10.1
  • 20

Pairwise test design

One of the most complex test design systems in testing is the pairwise test design. Pairwise test design works on the combinatorics system of mathematics, where we try to cover all the possible combinations using minimum inputs.

So, let’s take an example of a train ticket booking system. Currently, there are two trains:

Trains: train A and train B

In each of the trains, there are only three coaches: Coaches: Coach X, Coach XL, and Coach XXL. And there are two types of tickets

Tickets: Normal, Urgent

If you need to test for each of the inputs, it becomes 2x3x2 = 12 combinations. These can be listed as follows:


Input A Input B Input C
1 train A Coach X Normal
2 train A Coach X Urgent
3 train A Coach Xl Normal
4 train A Coach Xl Urgent
5 train A Coach XXL Normal
6 train A Coach XXL Urgent
7 train B Coach X Normal
8 train B Coach X Urgent
9 train B Coach Xl Normal
10 train B Coach Xl Urgent
11 train B Coach XXL Normal
12 train B Coach XXL Urgent

If coaches are expanded to 10, the combination becomes 40. If one more train is added, 60 combinations can be devised, and the number increases exponentially. Going exhaustive is not advisable due to a large number of inputs, therefore. Here, we follow the ideology of pairwise test design.

The ideology behind pairwise test design - Errors are most probable to occur when pairs are used instead of single inputs.

In the above table, a few combinations are repeated. You can remove them to devise unique combinations and test all 12 without putting 12 inputs in the software.

Deriving duplicates in this, we can remove 5 test cases and implement all 12 combinations in just 7 combinations as follows:


Input AInput B
1train ACoach X
2train ACoach Xl
3train BCoach Xl
4train BCoach XXL
5train BCoach X
6train ACoach XXL
7train ACoach Xl

This example has only a few combinations and so it can quickly be done manually. However, practically this may not be the case. You may even need to derive more than 50 thousand combinations depending on parameters and variables. It is better to use an online test design tool for pairwise test design to manage such cases. They are free and work effectively.

So, what is the benefit of using a pairwise test design? As seen in the above example, we have cut down almost 42% of combinations and can still cover 100%. This makes the testing process a lot faster and increases the quality without performing exhaustive testing.

Error guessing test design

After the most complex test design, you can conclude this section with the most simple test design technique, i.e., error guessing. This test design technique is only suited for experienced testers and QAs who can just see an application and recite various possibilities where an error can occur.

In error guessing test design technique, you do not follow any rules as seen in the previous ones. An experienced tester can write down a few scenarios as per their experience, and the testers can convert them to test cases accordingly. These cases might fall into one of the other test designs, but the main motive of these cases is to explore hidden areas that can cause errors.

Ideology behind error guessing test design technique - experience can bring out scenarios that the natural testing process might not cover.

Instinct-based test cases of experienced testers explore grey areas of the application.

Other than these test designs, one may also encounter exploratory test designs or decision table-based test designs, etc. However, these sub-divisions do not come under mainstream test design techniques.

Importance of Test design tools

While exploring the test design techniques, the reader can notice the work it demands from the tester to accomplish each design. The more we move ahead manually, the more time we consume and the more delay takes place in completing testing.

However, this is not the only issue in manual work. Another significant and maybe more important issue we face is judging the quality of test cases. How can we do that?

Let’s say we have one application with only one login page and nothing else. The requirement is:

  • Signing up on the page.
  • Log in succeeds with the correct credentials.
  • Log In fails with incorrect credentials.

For just three requirements, a tester can derive hundreds of test cases. We can keep putting in the email id with slight changes and increase the number of test cases or even refrain from writing corner cases and still manage to increase the count to more than a hundred. How can I or anyone judge the quality of test cases?

One solution that a lot of people come up with is test coverage or code coverage percentage analysis. If you cover 80% of the code through my tests, you can test 80% of the application. This, in reality, is a misconception and is an improper method to judge the quality of test cases.

Covering code does not mean covering complex cases. For instance, a login code as follows:

if $name != regex("^[a-zA-Z0-9_]*$"):
    entry prohibited
    redirect                    

This code will be executed ⅓ of the time always while 100% when you just input a number as a name. But that does not cover the cases harish1, harish23, etc., which are more likely to occur than 1, 2, or 3. So, we are covering the conditions theoretically but not complicated cases.

The answer to the question of judging the quality of our tests is that we cannot do it manually. And taking charge of creating test designs can make things even worse, considering how complex applications have become today with a long list of requirements to satisfy. A solution to this problem is test design tools that work just to create test designs with minimum help from testers.

Introduction to Test design tools

After briefing ourselves with test design methods, the definition of test design tools might be self-explaining. A tool that can create test designs is called a test design tool. However, exactly what features it should exhibit is neither lucid nor restrictive.

If all your requirements can be satisfied with the state transition test design, only the state transition test design tool is what you need. This is why we may find many test design tools on the internet and may need to use more than a couple in our project. So, here, we will focus on test design tool features in a generic sense without concentrating on a single type.

What to find in a Test design tool?

While searching for a perfect test design tool, remember to consider the following characteristics:

  • Minimum code, maximum efficiency - The test design tool should analyze the requirement and specifications of the application and generate a test design that takes minimum test code and provides maximum efficiency. Notice that the test design tool should be efficient, i.e., the test design should cover most of the complex cases testing the application inside out. In short, focus on quality rather than quantity.
  • Simple designs, complex functionalities - The tool should convert high-level requirements to simple designs that are understandable by the testers easily.
  • Reduce time - The test design tool should take considerably less time than manual efforts from the testers and QAs.
  • Should be cost-effective - The tool should be cost-effective and bring out good ROIs in the future.

While searching for a perfect test design tool, remember to consider the following characteristics:

  • Testcollab
  • pairWise Tool
  • Kualitee
  • Datamaker
  • BenderRBT

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How does a Test design tool work?

A test design tool focuses on acquiring the requirements and specifications and generates a test design according to the tool’s working. A generalized step-wise process is extremely hard to discuss because of the variety of test design tools working and the kind of output it provides. As a tester, you need to learn the tool first and then proceed.

To demonstrate a simple tool, we can pick up the “pairWise Tool”, which works in the pairwise test design department.

To generate the pairwise test design, open the online tool from their official website.

pairwise test design

This screen asks for the variables according to the application. Let’s say you have an application with 2 shops with 3 cakes and 2 chocolates in each shop. So, you need to enter these variables as follows:.

variables according to the application

Now, we need to click the button “Generate Pairwise” on the top, and an excel sheet with all the pairwise inputs will be downloaded.

generate pairwise

As seen, the 12 cases (2x3x2) are covered in just 7 combinations.

You can also press “Generate All Combinations” to generate the 12 combinations for analysis.

In addition, if you have some conditions between pairs, then that can be worked out in this tool too. For instance, Shop 1 does not have Cake 2. So, click “Edit Conditions” and put conditions as follows.

generate all combinations

Again click the Generate Pairwise button, and this time we get just 5 pairs in which Shop 1 is not combined with Cake 2.

generate pairwise button

This is the working of a single type of tool in a single test design. This will differ from tool to tool, technique to technique.

Conclusion

A test design, in short, can be considered to be a reference material for a tester. It will help test the application with minimum test cases and cover maximum possibilities. However, since an application cannot be tested linearly, we may need multiple test designs to cover all the areas.

This tutorial by Harish Rajora highlights the test design techniques, such as state transition and boundary value analysis, which are the principle behind a tool’s working. If you need to select a test design tool, you first must choose the technique for which you need the tool.

Frequently Asked Questions (FAQs)

What is a test design tool?

A test design tool takes requirements and specifications from testers and generates the best possible test cases. This may include graphs, flowcharts, or scenarios.

What are the best test design techniques?

Although one may find a long list of test design techniques, the following seems to be the best choice that fits each type of application: State transition test design, Equivalent class test design, Pairwise test design, and Error guessing test design.

Author's Profile

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Harish Rajora

Harish Rajora, He is a computer science engineer. He loves to keep growing as the technological world grows. He feels there is no powerful tool than a computer to change the world in any way. Apart from his field of study, he likes reading books a lot and write sometimes on Twitter.

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Salman Khan

Salman works as a Digital Marketing Manager at LambdaTest. With over four years in the software testing domain, he brings a wealth of experience to his role of reviewing blogs, learning hubs, product updates, and documentation write-ups. Holding a Master's degree (M.Tech) in Computer Science, Salman's expertise extends to various areas including web development, software testing (including automation testing and mobile app testing), CSS, and more.

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