Improve Software Quality with Negative Testing

While most software testing focuses on ensuring an application works as expected, negative testing follows a different approach. It breaks the system to uncover hidden vulnerabilities and flaws. Negative testing challenges the software with invalid inputs, unexpected user behavior, and extreme conditions to ensure robustness.

Despite the critical role negative testing plays, testing efforts generally fall into two main classifications: positive and negative testing. Both categories are equally important, but positive testing is more popular than negative testing, leaving negative testing underestimated.

With the rise of artificial intelligence (AI), negative testing has become more efficient and comprehensive. AI-driven tools can generate countless variations of invalid inputs, predict potential failure points, and automate complex scenarios. However, they also enhance the accuracy and coverage of negative testing.

What is Negative Testing in Software Testing?

Negative Testing, also known as failure testing or error path testing, is a critical approach in software testing that evaluates how an application handles unexpected, invalid, or malicious inputs. Unlike positive testing, which ensures that a system behaves as intended under normal conditions, negative testing challenges the system's robustness and reliability.

This testing technique is used to determine whether the application can gracefully handle:

• Invalid inputs
• Unexpected user behaviors
• System boundary violations
• Error-prone scenarios

Purpose of Negative Testing

The main goal of negative testing is to:

• Identify software vulnerabilities
• Prevent system crashes or data corruption
• Validate error-handling mechanisms
• Ensure the application behaves predictably under stress or invalid conditions

Why is Negative Path Testing so Important?

Let’s find out some key reasons why negative testing is so important:

1. Identify Hidden Vulnerabilities: Negative testing uncovers flaws that are not evident during normal operation. It helps reveal security gaps, performance issues, and logic errors that would go unnoticed.
2. System Robustness: Negative testing ensures the application remains stable by testing how the system handles incorrect inputs or unexpected behaviors. It strengthens the overall resilience of the software.
3. Prevents Failures: It simulates invalid user inputs or unexpected scenarios that could occur in production.
4. Product Reliability: Testing for invalid inputs and extreme conditions ensures the application performs consistently. It ensures the system reacts appropriately to incorrect actions, providing a more seamless user experience.

Why Do Testers Avoid Performing Negative Testing?

Despite its usefulness, it seems to have a negative reputation among software testers. Many professionals are hesitant to perform it because they believe it may unnecessarily cause a delay in the launch of the software product.

Some testers consider it a distraction that wastes time and resources. They are convinced it is better to pour their efforts into positive testing instead.

The lack of skills and knowledge also hinders testers from employing it. Not everyone understands completely how the software works and what its limitations are.

However, despite its name, it leads to positive results. It should be an essential part of your software testing strategy for the following reasons:

• Organizational Responsibility

  Your company is responsible for offering excellent software products to its clients. Negative testing, in tandem with positive testing, is necessary to ensure the stability of your application. You may not be able to guarantee that your program is entirely free from errors, but you must at least do your best to minimize failures through this testing.

• Client Satisfaction

  Your clients have entrusted software projects to your company because they believe you can create excellent software products. High-quality software is essential for online stocks, e-commerce, and other sensitive business matters.

It is crucial if you aim to attain client satisfaction. Still, it is up to your clients to decide if they will invest in the extra expenses necessary for negative testing.

How to Perform Negative Path Testing

These are some smart techniques you can utilize to perform negative testing on software applications:

• Boundary Value Analysis

  This method involves writing the test cases for values outside the boundary limits. For instance, your boundary limits are 1 to 100 if you are testing a text field that accepts data within the 1 to 100 character range.

• Equivalence Partitioning

  It is a technique that tests the functionality of a software program. It entails grouping the input values into various partitions. You will be testing some values in every partition.

• Error Guessing

  This procedure pinpoints the specific conditions that trigger failure or error messages. If possible, you should try to identify and correct the issue without a system crash. In some cases, an incorrect result may lead to an extreme “downstream” failure if the error condition is not immediately noticed and addressed.

• Checklists

  It is a basic but crucial method that documents the error conditions you plan to test. A software testing checklist is commonly used in tandem with error guessing.

• Anti-patterns

  If there are design patterns, anti-patterns are their antithesis. If the former is the best way of resolving an issue, the latter is a solution that does not work. Anti-patterns are the ideal source of negative tests.

• Exploratory Testing

  This technique increases your knowledge about the application while the test is ongoing. It may be conducted simultaneously with other tests. Exploratory testing can give you a clear picture of which aspects of the application work and which don't.

• Small-scale Test Automation

  This method uncovers memory errors, code defects, and other issues occasionally revealed in production use. It entails performing the same action thousands of times to see its effect on the program.

• Fuzz Testing

  This procedure involves random data input, which may cause unexpected failures, crashes, and issues. Unlike other negative test cases, there are no preset expected results in this case. It is simply an observation of what may occur because of arbitrary inputs.

• State Transition Testing

  It is a technique that is utilized to spot defects in the application. It originates from the concept that software can only exist in one particular state simultaneously. For instance, a program is considered to be in its normal state until an issue reveals itself.

What are the Common Tools for Negative Testing?

The following are the standard tools to perform negative testing in software testing:

1. Selenium: Allows testers to simulate invalid user inputs and test web applications for negative scenarios.
2. Apache JMeter: Simulate negative test cases by sending invalid or corrupted data to applications.
3. Postman: Enables negative testing by sending incorrect API requests and verifying the handling of the response.
4. TestComplete: Simulating invalid inputs and error conditions across different platforms.
5. SoapUI: Allows testers to perform negative tests by sending improper requests and monitoring how the system responds.
6. JUnit/NUnit: Allow developers to write negative test cases in code to test application behavior with invalid inputs and edge cases.

What are the Implementation Tips for Performing Negative Testing?

1. Create detailed test cases with invalid inputs and edge scenarios.
2. Focus on areas with critical business logic to catch high-impact failures.
3. Test the boundary limits of input fields and data types for potential breakpoints.
4. Automated tools are used to generate invalid inputs and run tests efficiently.
5. Test common user errors like invalid characters or empty form fields.
6. Ensure the application handles limits and errors gracefully without crashing.
7. Test for vulnerabilities like SQL injection or cross-site scripting.
8. Record test outcomes, failures, and system responses for better issue tracking.
9. Continuously update test cases to align with new features and functionality.

Negative Path Testing Scenarios

The purpose of it is to pinpoint possible application failures in different circumstances. Here are some potential situations where errors and crashes may unexpectedly occur:

1. Populating Required Fields

   Certain software and web pages showcase fields that the user must fill out. You can design a test that leaves the required fields blank so you can evaluate the program’s response to this scenario.

2. Correspondence Between Data and Field Types

   Most digital forms and dialog boxes are capable of receiving data in a particular form, such as text, number, date, and time. You can make a test where the wrong data type is entered into a control to see how the application reacts in this case.

3. Allowed Data Bounds and Limits

   Some software programs include input fields that only receive data that falls under a particular range of numbers or text. You may design a test that inputs a value lower or higher than the boundaries of a specific field.

4. Allowed Number of Characters

   There are web pages and applications with fields that only permit the user to enter a limited number of characters. You can conceptualize a test where more characters are entered in the field than is normally allowed.

5. Web Session Testing

   Certain web browsers require users to log in before loading web pages. You can prepare a test that attempts to open web pages in the application without logging in beforehand.

6. Reasonable Data

   Some programs and web pages feature fields with a reasonable limit. You can make a negative test that inputs invalid data into the field.

7. Interrupt Testing

   In the case of mobile app testing, simultaneous interruptions, for example, incoming calls, messaging, low battery, and network loss, to check how the app handles these interruptions.

8. User Interface Testing

   By providing invalid inputs to intentionally generate the error, we can check whether the error messages are correctly displayed and whether user-friendly information is displayed.

What is the Difference Between Positive and Negative Testing?

In contrast to negative testing, positive testing is software testing that ensures the application is working properly under normal circumstances. This table gives you an overview of the main differences between the two:

What are the Benefits of Negative Testing in Software Testing?

Positive testing has its advantages, but negative testing also has crucial benefits. These are just some of the perks of negative testing software applications:

• Identify Incorrect Bug Processing

  It allows you to avoid application failures caused by faulty bug processing. It helps confirm whether the software code stopped managing a programmed use case. It can also prevent situations where the client cannot access the data necessary for bug fixing.

• Identify Possible Weak Spots in Security

  Negative testing in software testing allows you to ensure that a client cannot access a personal account in the program if they are not permitted to do so by the organization. It enables you to prevent a group of users from using the application's specialized functions if necessary.

• Maintain a Clean Database

  A program's database will be in good condition if it only includes valid data. It can increase the possibility that only valid information is stored and displayed by the application.

• Enhanced System Robustness and Resilience

  System exposure to various failure conditions helps refine the error-handling mechanism and improve the quality, which helps achieve the enhanced robustness and resilience of the system.

How Does Artificial Intelligence (AI) Help Perform Negative Testing

Artificial Intelligence (AI) is revolutionizing the field of software testing, including negative testing, by automating and enhancing the process. AI is transforming the landscape of negative testing in software quality assurance by automating, enhancing, and accelerating the process. These advancements help identify potential issues and vulnerabilities in software applications, ultimately leading to more robust and reliable systems.

• Invalid Input Testing

  AI can automatically generate test cases with invalid inputs, such as entering letters in a numerical field. It ensures that the software handles these situations without crashing.

• Security Testing

  AI tools can simulate common security attacks, such as SQL injection, cross-site scripting (XSS), and cross-site request forgery (CSRF), to check how the software responds to potential threats.

• Performance Testing

  AI can stress-test a system by generating a high volume of user requests to see how the application behaves under load and identify performance bottlenecks.

• Negative UI Testing

  AI can simulate negative user interactions, like clicking multiple buttons at once or trying to perform actions that are not allowed, to check for unintended behavior.

• Root Cause Analysis

  AI-powered tools can help identify the root causes of negative testing failures. By analyzing logs, system behavior, and error messages, AI can pinpoint the exact source of the problem. This information is invaluable for developers to fix issues promptly. For example, in a social media application, AI can help trace the source of login failures or data corruption errors.

Conclusion

Negative testing is a key element of software testing. However, it can be a time-consuming and expensive process. You have the option of partnering with QASource to save time and resources. Our outstanding QA outsourcing services are the ideal solution to your software testing needs. Let our expert team of engineers handle your negative testing projects for the best results.