Understanding Positive Testing Vs. Negative Testing?

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Negative Testing in Software Testing

Positive and negative testing are two crucial techniques used in software testing to ensure the quality and reliability of a software application. These testing methods help uncover defects and validate the software’s behavior under different scenarios. In this blog, you will delve into the concepts of negative testing and positive testing, explore the associated testing techniques, and highlight the key differences between the two.

What is Positive Testing? 

It involves validating the software application’s expected behavior when provided with valid inputs and executing valid operations. In this type of testing, the tester focuses on verifying that the system functions as intended under normal circumstances. Positive testing ensures the software meets the specified requirements and performs its intended functions correctly.

During positive testing, testers execute test cases with valid inputs, ensuring that the software produces the expected outputs and behaves as expected. It helps identify software logic, user interface, or data processing flaws. It ensures the software functions accurately when users interact under normal conditions, providing a seamless user experience.

What is Negative Testing?

It involves validating the software’s behavior when provided with invalid or unexpected inputs or executing invalid operations. It aims to uncover defects and vulnerabilities by testing the system’s ability to handle abnormal or erroneous scenarios.

During negative testing, testers intentionally input incorrect, invalid, or unexpected data to verify that the software handles such situations appropriately. This type of testing helps identify how the software responds to exceptional conditions, such as incorrect user inputs, system failures, or security breaches.

Testing Techniques Used for Positive and Negative Testing

The following are the testing techniques used for negative and positive testing:-

  • Boundary Value Analysis with Examples

Boundary Value Analysis (BVA) is a testing technique used for both negative and positive testing. It focuses on testing the software’s behavior at the boundaries of input values. This technique helps identify defects that may occur due to incorrect handling of boundary conditions.
Let’s consider an example of a software application that calculates the discount on a product based on the purchase amount. The discount is 10% for purchases between $100 and $500 and 20% for purchases above $500.

For positive testing using BVA, the tester would select input values on the boundaries of the valid range. In this case, the tester would choose a purchase amount of $100 and $500 to ensure that the correct discount is applied.

For negative testing using BVA, the tester would select input values just outside the valid range. For instance, the tester would try a purchase of $99 and $501 to verify that the software correctly handles invalid input and either rejects it or applies the appropriate discount.

  • Equivalence Partitioning with Examples

Equivalence Partitioning is another testing technique used for both positive and negative testing. It involves dividing the input data into equivalence classes and selecting representative test cases from each class. This technique helps reduce the number of test cases while still ensuring adequate coverage.

Let’s consider the input field for a user’s age, which should be between 18 and 60 years.

For positive testing using equivalence partitioning, the tester would select test cases from the valid range of 18 to 60, such as 25, 35, and 50, to validate that the software accepts these values.

For negative testing using equivalence partitioning, the tester would select test cases from the invalid range, such as values below 18 (e.g., 16) and values above 60 (e.g., 65), to ensure that the software correctly rejects these inputs and prompts the user for valid age values.

Difference Between Negative and Positive Testing

The key difference between positive and negative testing lies in the test cases and the objectives of the testing process.

Positive testing focuses on validating the software’s expected behavior under normal conditions, ensuring it performs its intended functions correctly. It involves executing test cases with valid inputs and operations to verify that the software produces the expected outputs.

On the other hand, negative testing aims to uncover defects and vulnerabilities by deliberately testing the software’s ability to handle abnormal or erroneous scenarios. It involves executing test cases with invalid or unexpected inputs and operations to verify that the software appropriately identifies and handles such situations.

While the former aims to validate the software’s correctness and adherence to requirements, the latter focuses on identifying potential vulnerabilities, error-handling issues, and boundary problems.

Positive and Negative Test Scenarios

Positive test scenarios validate the software’s expected behavior under normal conditions, while negative test scenarios verify it under abnormal or exceptional conditions.

Positive test scenarios may include:

  • Successful user login with valid credentials
  • Successful purchase transaction with proper payment details
  • Accurate calculation of the total order amount after applying discounts

Negative test scenarios may include:

  • User login with incorrect or invalid credentials
  • Transaction failure due to an invalid credit card number
  • Handling unexpected system errors during a purchase transaction

Conclusion

Remember, positive and negative testing is crucial for ensuring the overall quality of your software application. So, make sure to incorporate both techniques in your testing process to achieve the desired reliability and user satisfaction level. Ready to take your software testing to the next level? Contact QASource to discuss your testing requirements.