Equivalence Partitioning: Step-by-Step Process for Efficient Test

April 15, 2024Aayush Saxena
Equivalence Partitioning Step-by-Step Process for Efficient Test

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In the world of software testing, ensuring the reliability and accuracy of applications is paramount. However, to save time and effort – testing needs to be efficient too. This is where testing techniques come into play. In this article, we will delve into the step-by-step process of how to implement and automate equivalence partitioning for efficient and effective testing.

Understanding Equivalence Partitioning

Equivalence partitioning is a black-box testing technique that allows testers to group input data into sets or classes, making it possible to reduce the number of test cases while still achieving comprehensive coverage. This technique is particularly useful when dealing with a large range of input values. Let’s walk through an example to understand the concept and process of Equivalence Partitioning.

Testing a Login Form

Suppose we have a login form with a username field. To apply Equivalence Partitioning, we can divide the possible input values into equivalence classes based on their expected behavior.

Equivalence Classes:

1. Valid Usernames: Alphanumeric usernames with a length of 5 to 15 characters.

2. Invalid Usernames: Usernames containing special characters or exceeding the length limit.

3. Empty Usernames: Leaving the username field empty.

Step-by-Step Process of Equivalence Partitioning:

1. Identify the input field: Determine the input field to be tested, such as the username field in our example.

2. Define equivalence classes: Categorize the possible input values into distinct equivalence classes. Each class represents a set of inputs with similar behavior or characteristics.

3. Determine representative values: Select representative values from each equivalence class. These values should cover the boundary conditions and critical scenarios within each class.

4. Create test cases: Generate test cases that cover each equivalence class. For example, one test case would include a valid username, another would include an invalid username, and a third test case would cover an empty username.

5. Execute the test cases: Run the test cases using the defined equivalence classes to validate the behavior of the system. Observe and record the results for each test case.

By following this step-by-step process, testers can effectively apply Equivalence Partitioning to streamline test case design and achieve comprehensive test coverage while minimizing redundancy.

Can this technique be implemented during test automation?

Equivalence partitioning is indeed a technique that can be seamlessly implemented during test automation. By leveraging automated tools and frameworks, we can effectively streamline the process of generating test cases based on the identified equivalence classes.

For example, let’s consider a scenario where we are testing a login form with an email field. Through equivalence partitioning, we can divide the possible input values into equivalence classes such as valid email addresses, invalid email formats, and empty fields. With the help of automated test generation tools, we can quickly generate test cases that cover each equivalence class, ensuring comprehensive test coverage while saving time and effort.

Examples of Equivalence Partitioning Technique

To further illustrate the practical application of the equivalence partitioning technique, let’s explore a couple of examples and delve into how they can be implemented using Testsigma, a powerful testing tool. By leveraging Testsigma’s intuitive interface and automation capabilities, testers can effectively implement Equivalence Partitioning in their testing workflows. 

I. Example – Testing User Registration Form

In this example, let’s consider a user registration form that requires input for the age field. The Equivalence Partitioning technique can be applied to divide the possible input values into different equivalence classes.

Equivalence Classes:

Valid Age: 18-60 (inclusive)

Invalid Age: Below 18 and above 60

Empty Age Field

Implementation with Testsigma:

  1. Using TestSigma’s intuitive interface, create a new test case for the user registration form.
  2. Add a test step to enter a valid age within the range of 18-60. This step represents the Valid Age equivalence class.
  3. Add another test step to enter an invalid age below 18 or above 60. This step represents the Invalid Age equivalence class.
  4. Include a test step to leave the age field empty. This step represents the Empty Age Field equivalence class.
  5. Run the test case in TestSigma’s automation environment, which will execute the test steps based on the equivalence classes defined.
  6. TestSigma will generate comprehensive test reports, highlighting the results for each equivalence class, allowing you to identify any issues or defects

You can Automate your Equivalence Partitioning Tests

For Web, Mobile and Desktop Applications with Testsigma

Check out Testsigma

II. Example: Testing Credit Card Validation

Consider a scenario where a credit card validation functionality is being tested. Equivalence Partitioning can be applied to the credit card number input field.

Equivalence Classes:

Valid Credit Card Numbers

Invalid Credit Card Numbers (e.g., incorrect length, invalid checksum)

Empty Credit Card Field

Implementation with Testsigma:

  1. Create a new test case in Testsigma for the credit card validation functionality.
  2. Include a test step to enter a valid credit card number. This step represents the Valid Credit Card Numbers equivalence class.
  3. Add a test step to enter an invalid credit card number, such as a number with an incorrect length or an invalid checksum. This step represents the Invalid Credit Card Numbers equivalence class.
  4. Include a test step to leave the credit card field empty. This step represents the Empty Credit Card Field equivalence class.
  5. Execute the test case using Testsigma’s automation capabilities.
  6. Testsigma will automatically validate the credit card numbers based on the defined equivalence classes and provide detailed test reports.

Why Equivalence Partitioning?

Equivalence Partitioning enhances test coverage, saves time and effort, promotes error detection, enables test case reusability, improves maintainability, and ensures comprehensive testing. Let’s explore these benefits in more detail below and see why you should choose Equivalence Partitioning. 

Enhanced Test Coverage: Equivalence partitioning allows us to cover a wide range of input values with a minimal number of test cases, ensuring thorough testing without exhaustive combinations.

Time and Effort Efficiency: By reducing the number of test cases, equivalence partitioning helps save time and effort during the testing process, making it more efficient and cost-effective, which can be crucial when you are, for instance, testing the HTML/CSS of mass emails for your marketing campaigns.

Error Detection: Equivalence Partitioning aids in uncovering defects by focusing on critical and boundary values within each equivalence class, increasing the likelihood of identifying potential issues.

Test Case Reusability: Equivalence Partitioning promotes test case reusability, as the defined equivalence classes can be used to generate additional test cases for future testing cycles, reducing duplication efforts.

Improved Maintainability: With Equivalence Partitioning, maintaining test cases becomes easier, as changes to the underlying equivalence classes can be reflected across multiple test cases, ensuring consistency and reducing maintenance efforts.

For you to better understand Equivalence Partitioning, here are a few Pro’s and Con’s –

Advantages of Equivalence Partitioning:

  1. Enhanced Test Coverage: Equivalence partitioning allows testers to cover a wide range of input values by selecting representative test cases from each equivalence class, ensuring comprehensive coverage while minimizing redundant testing.

  2. Efficiency in Test Case Design: By dividing input values into equivalence classes, test case design becomes more structured and systematic. It helps testers identify critical and boundary values for each class, enabling focused testing on potential areas of failure.

  3. Time and Effort Savings: Equivalence partitioning helps optimize testing efforts by reducing the number of test cases needed while still maintaining sufficient coverage. This leads to time and effort savings, making the testing process more efficient.

  4. Defect Detection: Equivalence partitioning increases the likelihood of detecting defects by targeting specific equivalence classes and their boundaries. By testing representative values from each class, testers can identify potential issues or failures.

Disadvantages of Equivalence Partitioning:

  1. Limited to Input Values: Equivalence Partitioning primarily focuses on input values and their equivalence classes. It may not address other factors, such as system behavior or interaction between components, which can also contribute to defects.

  2. Complex Scenarios: In complex scenarios with multiple inputs or dependencies, defining accurate and comprehensive equivalence classes can be challenging. It requires careful analysis and consideration of various factors, potentially increasing the complexity of the testing process.

  3. Requirement for Domain Knowledge: Equivalence Partitioning relies on domain knowledge and understanding of the system under test. Testers need to have a clear understanding of the input values and their classifications to accurately identify and define equivalence classes.

  4. Potential for Overlooking Defects: While Equivalence Partitioning improves test coverage, it does not guarantee the detection of all defects. There is a possibility of overlooking specific scenarios or edge cases that fall outside the defined equivalence classes.

By understanding the advantages and disadvantages of Equivalence Partitioning, testers can make informed decisions about when and how to effectively apply this technique in their testing approach.


Equivalence Partitioning is a powerful testing technique that enables comprehensive test coverage while reducing the number of test cases. This article provides a step-by-step process for implementing Equivalence Partitioning, along with real-world examples and references. With Testsigma, testers can seamlessly integrate Equivalence Partitioning into their test automation workflows, enhancing efficiency and accuracy in software testing.

Frequently Asked Questions

Q1. Is Equivalence Partitioning a black box test?

Yes, Equivalence Partitioning is a black-box testing technique. It focuses on testing the functionality of the software from an external perspective, without considering the internal structure or implementation details. Testers identify and categorize input values into equivalence classes based on their expected behavior, without knowledge of the internal workings of the system. This allows for comprehensive testing while maintaining independence from the internal code.

Q2. How many test cases for equivalence partitioning?

The number of test cases for equivalence partitioning depends on the number of identified equivalence classes. In general, for each equivalence class, at least one test case is needed to represent that class. So, the total number of test cases would be equal to the number of identified equivalence classes. However, it’s important to note that additional test cases might be required to cover specific boundary or edge cases within each equivalence class. Therefore, the exact number of test cases may vary based on the complexity of the system and the identified equivalence classes.

Q3. Who uses equivalence partitioning?

Equivalence partitioning is utilized by various stakeholders in software testing, including manual testers, test automation engineers, QA analysts and managers, developers, and non-technical product team members. By categorizing input values into equivalence classes, it enhances the effectiveness and accuracy of testing efforts, leading to higher-quality software products.

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