What Is an Edge Case Testing? How To Find and Prioritize

Edge case testing is a method of verifying behavior of software systems under extreme or unlikely conditions. This process covers cases other than the typical uses. Such cases usually take place either at the edge of the input range or include problems that are out of the ordinary.

It is important to perform edge case testing as it can expose the hidden defects that you cannot see during regular testing.

By recognizing and organizing edge case testing, the developers and testers can make the most secure possible systems that can cope with unexpected situations effectively.

What are Edge Test Cases?

Edge test cases consist of examining the behavior of the software in extreme conditions or in the limits, where the software will probably start to act strangely. These tests are intended to imitate rare or different situations that make sure that the software is capable of handling unpredicted events.

A quick example of an edge test case would be to test a login system with a user name that is longer than allowed character limit. Another is inserting negative numbers where only positive ones are expected.

The issue with edge cases is that they often represent the scenarios users come across under real conditions, even if they are rare. Spotting and correcting such edge cases guarantees the flawless performance of software and avoids damages that occasionally come up via the operation of the software.

Examples of Edge Test Cases

To grasp the concepts of edge cases, let’s have a look over the following three real-life examples:

• Login System

Scenario: A user enters either the wrong username or password.

Expected Result: The system will not allow access and will explain a correct error message.

• Input Validation

Scenario: Typing an input with content that is longer than the set limit, e.g., 256 character string in a field with the limit of 255 characters.

Expected Result: The input should be handled by the system flexibly, and it should be either rejected or truncated with the appropriate message.

• Concurrent Requests 

Scenario: Concurrent use of server resources by multiple users.

Expected Result: The system is capable of handling concurrency without errors and thus maintaining fairness among users.

Why are Edge Cases Important?

Why do edge cases play a crucial role in software testing because they are the ones who reveal issues and vulnerabilities through scenarios that are usually overlooked in the regular testing.

Here’s why they are important:

Identifying Hidden Issues: One of the things that the edge cases help with is that they might reveal bugs or weak points that will not be found under regular testing circumstances. Those problems can, if not tackled, result in system failures or compromised user experiences.

Improving User Experience: Dealing directly with the outlying cases benefits in that users will face fewer mishaps, and it will make their overall experience better and their trust in the product.

Ensuring System Robustness: Edge cases testing implements software preparedness for bizarre situations and therefore the system is more safe and reliable in the real environment.

Reducing Risks: In areas such as finance and healthcare, overlooking edge cases might have very serious effects. The testing of edge cases guarantees fulfillment of all the standards and minimizes the risks.

How to Find Edge Cases in Software Testing

To discover edge cases, you need to have a complete understanding of the software’s requirements and different user interactions. Below are some of the solutions that are to be found for such cases:

• Boundary Value Analysis (BVA):

Mainly inspect on the border of expression input range. Example: For instance, in a username field, the possible values range can be set at 6–12. Thus, you should test it with 5, 6, 12, and 13 characters to identify potential issues.

• Equivalence Partitioning:

Break them into groups of expected behavior and check one thing from each group. Example: For a field taking alphanumeric values, verify with one alphabetic and one numeric input concerning the scope.

• Scenario-Based Testing:

It involves the use of real-life situations and extreme user scenarios. Example: Testing the application work in instances when a call breaks a transaction or the battery dies in the middle of the process?

• Analyze User Feedback:

The unexpected scenarios in real-life reports of consumers are the primary sources of these trouble spots. Example: A message from a client comes in that says he/she has been logged out of a session that has been open for a rather long time of inactivity. This leads to checking the timeout functionality for session use then.

Manual vs. Automated Edge Case Testing

During the testing of edge cases, both manual and automated methods have their unique advantages as well as certain limitations.

Let’s discuss the differences:

Manual Edge Case Testing

Advantages:

• Helpful for exploratory testing, uncovering the rare scenarios with a supportive human intuition.
• Moreover, it is the best bet if the testing of highly complex user interactions and the subject of the case will be the theme, like UI/UX.

Challenges:

• Time-consuming and human error is very much possible.
• Difficult to reproduce scenarios consistently.

Automated Edge Case Testing

Advantages: 

• Enables the repeated testing of pre-defined edge cases with a steady level of accuracy.
• Progresses regression testing in times of a complex system.
• Tools such as Selenium, Appium, or Testsigma help in achieving testing on different platforms more efficiently.

Challenges: 

• The initial setup is a time-consuming task that also requires some expertise.
• It is restricted to testing only objective situations and cannot handle out-of-the-blue situations completely different from those that are set by the scripts.

When to Use Each Approach

• Use manual testing for new edge cases, assess the subjective experiences, and implement new and creative scenarios.
• Use automation for repeating, predictably, and with uniformity across environments running tests.

Mixing both manual and automated processes makes the thorough testing of edge cases with pristine precision, whereas it takes less time and resources into account.

How to Prioritize Edge Cases

Edge cases do not happen often, but they can seriously affect user experience or system performance. For the successful implementation of testing, these cases are given priority. Here’s how to do it:

1. Assess Business Impact

• Identify edge cases that may make users lose trust, harmful, or bring no revenue.
• Example: A payment gateway collapsing under heavy transaction volumes would mean a grave business impact.

2. Evaluate User Safety and Legal Compliance

• Industries like the healthcare or fintech sector will be required to prioritize the edge cases which play a part in user safety or compliance.
• Example: A medical app must handle incorrect data entries to prevent misinformation.

3. Consider Likelihood of Occurrence

• Even if very rare, for instance, some edge cases would be more likely to happen in the real world.
• Example: Trying out the app with low band width or distraction interference.

4. Look for User Feedback

• The feedback given by the end customers is helpful to reveal some of the unidentified scenarios in the production cycle.
• Example: A user can complain about a bug he got when he was on the train multitasking between apps.

5. Adopt a Risk-Oriented Testing Strategy

• Prioritize edge cases according to both risk-based approach factors such as probable consequences and likelihood of occurring. Starting with high risk-high impact scenarios first.

Prioritization Framework:

• High Impact + High Likelihood = Test immediately.
• High Impact + Low Likelihood = Test when resources allow.
• Low Impact + High Likelihood = Consider lower priority.
• Low Impact + Low Likelihood = Optional testing.

Tips and Best Practices for Edge Case Testing

The successful testing of edge cases should be done strategically. Below are some practical tips and techniques to ensure complete coverage:

1. Think Like a User

• Imagine you are the user who uses the software, and think of the possible mistakes that you could make.
• For example, what if a user clicks a button several times in quick succession without realizing it?

2. Test Unlikely Scenarios

• Fortify the quality of software by testing real-time and rare interruptions like phone calls or a draining battery.
• For instance, how does an app handle incoming notifications during a file upload?

3. Use Data Variations

• Try different inputs beyond normal limits, while dealing with negative values, null values, and special characters.
• Example: I.e., you enter some 0 or -1 in a field of the receipt of only positive integers, and you get an error message.

4. Embrace Iterative Testing

• Go through the edge cases again during every development cycle to adapt new features and changes to the software.
• Example: Updating tests for an expanded character limit in a username field.

5. Use Automation When Feasible

• To save time carry out the tests via automation tools as repeating and predefined issues.
• Example: Automating tests for maximum input size across all form fields.

6. Document Edge Cases

• Keep a detailed account of identified edge cases, test scenarios, and results in order to refer back to them in the future.
• For example, a common bank of edge cases can be useful for checking whether any scenarios are missed during subsequent testing cycles.

7. Learn from Feedback

• Collect feedback from the real users and also, go through the bug reports to find out the edge cases that have been missed.
• Example: The failure of a certain interaction may expose an unanticipated edge case.

By incorporating these tips into your testing strategy, you can address potential weaknesses and enhance your product’s reliability and user experience.

Edge Case Testing Before Product Release

Edge testing before product release is crucial so that even the rarest ones are assured of their real-world scenarios. Here’s why edge case testing is crucial pre-release:

1. Identifying Unexpected Failures

• Edge case testing helps in identifying potential bugs that may cause inconvenience to the user experience.
• Example: To test a shopping cart with the maximum number of items a system can handle without a crash.

2. Ensuring Seamless User Experience

• A system that correctly deals with edge cases will surely make the customers satisfied and buy again.
• Example: Preventing app crashes when users enter emojis into text fields.

3. Enhancing Product Stability

• Testing of the boundary scenarios decreases the probability of crashes under extreme conditions.
• Example: Simulating peak traffic loads on a website to determine its functionality during sales events remains stable.

4. Diluting the Possibility of failure

• In industries like healthcare or finance, edge case failures can have significant consequences.
• Example: A financial app should be able to support edge cases like a high transaction or incorrect currency format.

5. Boosting Market Readiness

• A product which passes the edge case tests with flying colors is undoubtedly much more durable and is ready to handle real-world challenges.
• Example: A mobile app with consistent performance across different network speeds enhances brand reputation.

For instance, an app that runs on different network speed platforms without performance inconsistency may add brand value to the company.

Checklist for Pre-Release Edge Case Testing

• Finalize all inputs at the boundary edge.
• Emulate device disruptions like calls or had a power disappearance.
• Test the system under stress like high traffic or load data.
• To check consistency using various devices, browsers, or OS versions.

By considering the edge case before release, you guarantee the provision of a seemingly perfect and flawless product to the users, hence decreasing the chance of any problems occurring after the product’s release.

The Role of User Feedback and Beta Testing

User feedback plus beta testing turn out to be particularly efficient at identifying edge cases that may be missed in internal testing. Here’s how they contribute:

1. Capturing Real-World Scenarios

• Beta testers use the software under various conditions, including the real world, which allows them to come across issues that developers might never have thought of.
• Example: A beta user encounters a problem with an app that crashes when buttons are switched back and forth.

2. Learning from User Behavior

• In-depth observation of users during the beta test phase gives the opportunity to notice unorthodox techniques of usage.
• Example: A user puts emojis into a numerical field, resulting in a crash.

3. Identifying Overlooked Edge Cases

• Users present new insights into scenarios overlooked during the development of the product.
• Example: Feedback may pinpoint a problem with an app’s behavior when the battery is low.

4. Iterative Improvement

• User feedback integration in the regular form serves as the perfect tool for refining edge case handling.
• For instance, apart from beta testing, the development team might be facing edge case issues when the network goes down or it is too slow.

User feedback inclusion and beta testing are the perfect combination that ensures a product is robust enough to function properly in the real world. These tools are a great way to tackle edge cases that come out in real user experience.

Iterative Development and Edge Cases

Iteration in the development is a principal appliance to address the edge cases. Here is why:

1. Continuous Identification of Edge Cases

• Each development version promises discovering and examining new edge cases.
• Example: When a new feature is added, the dependent edge cases can be identified and tried out.

2. Adapting to Changes

• The submission of repeated cycles guarantees the system to be durably resistant with the evolution of the requirements.
• Example: Getting more characters for the users? names means the appearance of new edge cases in the input results.

3. Regular Testing and Refinement

• Testing all edge cases in every iteration cuts the possibility of unplanned problems significantly.
• For Example: Every sprint contains runs of regression tests for the previously defined edge cases.

By the instrumentalization of edge test the periodic development, teams can anticipate and solve problems, ensuring a confident quality and reliability.

Improve Your Edge Case Testing Today

Regular edge case testing should be considered for producing robust and stable software. The team can ensure the product’s functionality in even the most extreme conditions by identifying, listing, and addressing edge cases.

In addition, getting the insights from the end-user feedback and beta testing can help to find real-world edge cases that might be overlooked otherwise.

At Testscenario, we emphasize a combination of these testing methodologies that results in the most efficient and precise validation process. Contact us to obtain more comprehensive information on our services or hire a tester.

Frequently Asked Questions (FAQs)

1. What is the difference between Base case and Edge case? 

• Base case is a simple, fundamental scenario which is used as a starting point for problem-solving.
• An edge case is a situation that happens at the boundaries of expected input or behavior. It tries the application’s response on extreme or unusual situations.

2. What are some common examples of Edge cases? 

• Inputting invalid or extreme data, such as very large numbers or special characters.
• Simulating interruptions, like app behavior during low battery or network loss.
• Testing concurrency, such as multiple users attempting the same action simultaneously.

3. How can Edge case testing improve product quality? 

• It helps uncover unknown problems, interprets that the quality of the software is robust even when the critical conditions may arise. It enhances user satisfaction by reducing errors and unexpected behavior.
• By addressing edge cases, software teams can build reliable, high-performing products that meet user expectations and thrive in real-world scenarios.