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False positive & false negative in software testing

Explore the challenges of false positives and negatives in software testing. Discover their effects, root causes, and effective minimizing strategies. Equip yourself with insights to improve the accuracy and reliability of your testing procedures.

Written byArman
Published OnWed Aug 25 2021
Last UpdatedWed Feb 21 2024

Understanding false positives and false negatives is essential in software testing, just as in medical diagnostics. A false positive in a health screening may incorrectly indicate the presence of a condition. In contrast, a false positive in software testing may imply the presence of a bug that does not exist. False negatives, on the other hand, ignore actual bugs, similar to missing a critical diagnosis in medicine. These testing results are critical, influencing the software development lifecycle through decision-making, resource allocation, and overall product quality. This article highlights the vital role that accurate testing plays in both software development and medical fields, ensuring a comprehensive understanding of these critical concepts.

False Positive & False Negative analogy

Experts in automated software testing have borrowed False Positive and False Negative terms from the medical examination field. In the medical field, the purpose of a test is to determine whether the patient has a particular medical condition or not.

The words positive and negative relate to the result of a hypothesis. Positive implies that the hypothesis was true, and negative means that the hypothesis was false.

With that said, the result of a medical examination can be one of the following items:

Test ResultDescription
True Positivesuggests that the patient does have the medical condition.
False Positivemistakenly indicates that the patient does have the medical condition when there is none.
True Negativesuggests that the patient does not have the medical condition.
False Negativemistakenly indicates that the patient does not have the medical condition when in fact, the patient has the disease.

Depending on the desired test result, both positive and negative can be considered bad. For example, in a test for COVID, you want a negative test result. Although a positive result is deemed to be bad, a False Negative is the worst. Thus, while you’re under the impression that you don’t have the COVID disease, you do, and therefore may not be aware that you need medication or spreading the virus to others.

False Positives and False Negatives Testing

Automated tests in software testing are responsible for the verification of the software under test and for catching bugs. In this context, positive means that at least one test found a bug or a malfunction feature. Moreover, negative means no test found a bug or malfunction feature in the code.

Ideally, all automated tests should give negative signals. However, in reality, some tests show False Positive or False Negative signals.

False Positives in Software Testing

A false positive in software testing happens when a test incorrectly detects a problem, such as a bug, that does not exist. This situation is similar to an alarm system that goes off even when no intruder exists.

For example, imagine a scenario where a testing suite flags a piece of code as vulnerable to SQL injection attacks. Developers may spend hours reviewing and sanitizing code only to discover that the test was wrong and the code was never at risk.

A false positive indicates a bug when there is none.

False positives have an impact that goes beyond simply wasting time and resources. They can lead to a “cry wolf” scenario in which developers, overwhelmed with false alarms, begin to ignore test results entirely, potentially ignoring real issues. Additionally, the effort to track down these non-existent bugs can cause project delays, resulting in missed deadlines and additional costs. Maintaining the balance between awareness and efficiency is vital in a development environment; therefore, reducing false positives is an important goal.

False Negatives in Software Testing

A false negative in software testing occurs when a test fails to detect an existing flaw or bug, resulting in the inaccurate conclusion that the software is problem-free.

Consider a scenario in which a software application handles financial transactions. If a security vulnerability test fails to find a real issue, such as a flaw that could allow unauthorized access to financial data, the consequences could be awful.

A false negative indicates no bug when there is one.

False negatives pose significant risks because they mislead developers and stakeholders, potentially leading to the release of unstable or unsafe software. This error can result in operational failures, data breaches, and a loss of user trust and satisfaction. Detecting false negatives is critical to guaranteeing software reliability and security. To find hidden vulnerabilities, it is necessary to perform strict testing, update test cases on a regular basis, and implement comprehensive testing strategies such as dynamic analysis and penetration testing. The goal is to ensure that when software is released, it fulfils the highest quality and security standards, protecting both the end-user experience and the development organization’s reputation.

Root Causes and Occurrences

Software testing can produce false positives and false negatives due to a combination of human and technical factors. Understanding these root causes is essential to creating strategies that reduce their effects. Here’s a breakdown of specific causes:

Automation Script Flaws

The foundation of automated testing processes is automation scripts. They are not immune to flaws, though. Scripts that are outdated or incorrectly written may result in false positives, which occur when the script fails a test because of an error in the script itself rather than an issue in the application being tested.

For example, if a script meant to verify user login isn’t updated to adapt to changes in the UI of the login form, it may fail and produce a false positive.

On the other hand, if the script ignores specific conditions that lead to a bug’s manifestation, false negatives may result. This could occur in complex systems when the script fails to consider all potential user interactions or data states, leading to missing important problems.

Unstable Test Environments

The stability of the test environment has an important effect on the reliability of test results. An unstable test environment might result in inconsistent test results, leading to both false positives and negatives. Environmental issues such as network latency, incorrect configuration, or data pollution from previous tests can all have an impact on the test’s ability to accurately evaluate the software’s functionality.

For example, a test case checking the performance of a web application may pass in a controlled test environment but fail in a production environment because of unexpected network latency, resulting in a false negative regarding the application’s performance under real-world conditions.

Oversight in Test Case Design

The design of test cases is an important aspect of discovering software flaws. Poorly designed test cases may fail to cover every aspect of the application’s functionality or might not align with the requirements, resulting in false negatives.

For example, if a test case designed to verify a payment processing feature does not test all payment methods supported by the application, it may miss problems with specific payment methods.

On the other hand, overly strict test cases may identify non-critical changes from expected outcomes as failures, resulting in false positives. This is commonly seen in UI testing, where minor and insignificant changes to the UI layout are flagged as errors.

Catch false negatives in tests

False Positive tests are easy to catch. When a test fails, we can look at the root cause for the failure and decide whether it was a false positive or not. How about false negatives? How to catch them? Remember, a test with false negative lies to you by not failing when it should fail.

Practically, one reason why a test case does not fail can be because of a False Negative signal. Should we lose our faith in automated software testing, then? The answer is: No.

To catch false negatives in tests, one should practice a technique known as mutation testing.

Software engineers exercise mutation testing by changing the code and introducing a bug, which is continued by running the test responsible for catching the bug. In this situation, a test that passes gives us a false negative.

Minimizing False Results in Testing

Preventing false results in software testing, including both false positives and false negatives, requires a strategic approach to ensuring software product integrity and reliability. By implementing specific strategies, teams can significantly increase the accuracy of their testing processes. In this section, we will go through some of the best practices to prevent false positives and false negatives.

Strategies to Minimize False Positives

  • Refine Test Case Design: To prevent misinterpreting non-issues as bugs, break down complex tests into smaller, more focused ones targeting specific functionalities.
  • Utilize Reliable Automation Frameworks: To reduce tool-related errors, use open-source frameworks supported by active communities.
  • Conduct Regular Code Reviews: Have peers evaluate both application code and test scripts to discover flaws early and avoid extra debugging efforts.
  • Mirror the Production Environment: Use Docker containers or virtual machines to mirror production settings in the testing environment, ensuring test results are consistent and reliable.

Strategies to Reduce False Negatives

  • Comprehensive Test Planning: Create detailed test plans that cover all parts of the application, including edge cases, to guarantee that no functionality is ignored.
  • Implement Mutation Testing: Use tools to make tiny code changes and see if tests can detect them, showing gaps in test coverage.
  • Adopt User Story-Based Testing: Create tests based on real-world user scenarios to capture a variety of application behaviours and potential issues.
  • Use Code Analysis Tools: Prioritize testing efforts based on static code analysis insights, focusing on areas identified as high risk for potential problems.


This article discussed false positive and false negative results in software testing, as well as their causes and how to prevent them. As we discussed, false negative results are worse than false positives since bugs remain in the code indefinitely. We introduced a technique known as mutation testing. Mutation testing enables test engineers to identify false negatives in code. Furthermore, we outlined some best practices for avoiding false positive and false negative outcomes in your tests.

We hope this article was beneficial. If you have any questions or suggestions, please feel free to reach out to us via our contact form or Twitter.

Frequently Asked Questions

We got an answer for your questions

  • What exactly are false positives and false negatives in software testing?

    False positives happen when a test incorrectly detects a bug in software that does not exist, resulting in unnecessary investigation. False negatives happen when a test fails to identify an actual bug, claiming the software is bug-free.

  • Why do false positives and false negatives matter in software testing?

    These flaws can result in wasted resources, unnoticed errors, and, potentially, the release of faulty software. Understanding and managing them is critical to maintaining software quality and reliability.

  • What causes false positives and false negatives?

    Common causes include errors in automation scripts, unstable testing environments, and mistakes in test case design. Each of these circumstances can result in misleading test findings that either raise false alarms or mask underlying issues.

  • How can I minimize false positives in my testing processes?

    To reduce false positives, simplify test automation, maintain scripts and environments, and use robust testing frameworks. Ensuring test cases are clear and aligned with actual software functionality is also beneficial.

  • What strategies may be used to reduce false negatives?

    Comprehensive test planning, which includes mutation testing and extensive code reviews, is a good strategy. To find hidden flaws, ensure all potential paths are tested, and the tests reflect real-world events.

  • How do continuous integration and deployment (CI/CD) approaches impact these issues?

    CI/CD approaches contribute to test reliability by making testing a fundamental part of the development process, allowing for early detection of potential false positives and negatives and facilitating quicker fixes.

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