What is Risk Based Testing: With Best Practices

OVERVIEW

Risk based testing (RBT) is a type of software testing that focuses on identifying and prioritizing high-risk areas of the software applications being tested. In simple terms, risk based testing is an approach that evaluates the features of software applications at high risk of failure based on software complexity.

Even though there are other software testing types like white box testing, grey box testing, and system testing that focus on testing every feature of software applications, why do we need risk based testing?

In the software development process, testing is indispensable for assuring the quality of software applications and evolves with time by introducing new software testing techniques and methodologies. Its primary focus is thoroughly testing every component, feature, line of code, and others.

However, an organization may face time and budget constraints that force the development team to make the most of it in the limited resource. In this case, the focus is given more to the features or components of software applications that matter the most. Here comes risk based testing, which allows testers to focus their time and resources on the testing software's most critical areas and improve the product's overall quality.

What is Risk Based Testing?

Risk-based testing is a testing approach that prioritizes the features and functions to be tested based on the risk of failure. It's a strategy that focuses on the areas of the software that carry the highest risk, helping teams to use their testing resources more efficiently.

Risk based testing is an essential approach to software testing, helps reduce testing efforts and costs, identify critical defects early in the Software Development Life Cycle, and ensures the delivery of high-quality software applications to end users. Using Risk based testing, software professionals can make informed decisions about the testing process, focusing their efforts on areas that pose the highest risk to the software applications.

The factors that pose a high risk to software applications may include complex code, code critical to the function of the software application, etc. However, risk levels are also impacted by the type of features or software applications being developed. In risk based testing, such factors are addressed and help focus on the part of the software application that is more likely to encounter bugs.

Why perform Risk Based Testing?

Risk based testing serves a multifaceted purpose. Primarily, it establishes a framework to develop transparent communication among stakeholders concerning the software project risks. This framework helps define standard communication within the team, making risks visible and more amenable to being fixed.

The need for risk based testing arises because it is not always possible to exhaustively test every aspect of software applications within the available time and budget. By identifying and assessing the risks associated with the software applications under test, a risk based testing approach can help testers focus their testing efforts on the areas of the software applications that are most critical and likely to cause issues.

This can help ensure that the software applications are thoroughly tested within the available time and budget and that the most critical issues are addressed before the software applications are released to users.

Risk based testing can also help identify and mitigate risks early in the development process, which can help reduce the cost and impact of defects discovered later in the development cycle or after the software application is released.

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Real-World Examples of Risk Based Testing

Suppose a software testing team works on an eCommerce website that allows customers to purchase products online. Your team has identified the following risks:

• The payment gateway is not secure, leading to the potential for unauthorized access and theft of customer payment information.
• The search functionality does not return accurate results, causing frustration for customers and potential loss of sales.
• The checkout process is not user-friendly, leading to abandoned shopping carts and potential loss of sales.

Based on these risks, your team would prioritize testing efforts accordingly. For example, you may allocate more resources to testing the payment gateway to ensure it is secure and prevent potential breaches. Additionally, you would prioritize testing the search functionality and checkout process to ensure they are user-friendly and accurate to avoid losing customers.

By adopting a risk based testing approach, your team can focus its resources on areas of highest risk to ensure that critical issues are addressed first. This approach can help you identify and mitigate potential problems before they become major issues and ultimately deliver a higher-quality product to your customers.

Benefits of Risk Based Testing

Risk based testing is an essential part of software testing and offers several benefits in ensuring the quality of the software applications. It is important to know its benefit to broaden the knowledge of risk based approach in testing and understand its wide use in software testing. Here are some of its key benefits:

• It allows you to be more efficient with most of the valuable resource time as you focus only on the high probability of risk of getting tested.
• Improve quality and functionality of the software applications because higher risk areas are prioritized and ensure that most critical functions are tested first.
• It tests all crucial functionality of the software application and provides a real-time understanding of their risk.
• It focuses on cost reduction, productivity, and test delivery.
• Test effort allocation can be done efficiently based on the risk assessment.
• Optimize the test with a defined risk analysis method.
• The high-risk area of software applications can be identified early, and its fix can be done before it becomes a more significant issue.

Features of Risk Based Testing

Risk based testing is essential to develop high-quality software applications and ensure no risk is involved that could impact its functionality. To get started with this, you must understand the key feature of risk based testing. Here are some of those:

• Order of the testing cycle in risk based testing prioritizes the execution of test cases with higher levels of risk over those with lower risks, thereby minimizing potential risk to the business.
• This approach facilitates allocating more resources to testing activities that involve new functionalities or require extensive research and development.
• It is an iterative process that continuously identifies risks, breaking them down into smaller units to enable efficient risk management.
• The risk based test strategy matches the level of test efforts to the level of risk involved in software applications. For example, more is the risk, and more is the test effort.

When to use Risk Based Testing?

To perform risk based testing correctly, it is essential to know the scenario where it can be implemented. With this, you can execute it at an accurate time. Here are some situations when it should be performed.

• The software application having time, resource, and budget constraints.
• Software applications where you can detect risks or vulnerabilities to SQL injection attacks.
• In Agile, performing risk based testing helps complete testing in a defined sprint to maintain the quality of the software application.
• When there is a need for security testing in a cloud computing environment.
• The software applications with high-risk factors, for example, lack of business domain knowledge.
• The long-term software development project requires critical management.
• Software development projects need lots of research and development. Here risk based testing will help better manage any high-risk area of the software application.

Defining and Determining Risk in Software Testing

Risk in testing is the occurrence of unexpected events that impact the software application's success and quality. Such events might have happened in the past or may be an issue for future occurrences. This may affect the cost, technicality, and quality of the standard of the software application.

The risk may include errors, issues, vulnerabilities, and defects that negatively impact the software application's functionality. The main purpose of risk assessment is to find and evaluate such risks and determine their level for prioritization of testing efforts.

However, risk assessment is challenging; how can you prioritize or determine the level of risk? To answer this, you have to look at three crucial aspects of software applications to determine the risk level:

• Criticality: The term criticality refers to the measure of the impact of a bug on a software application to get an idea of its severity. When a software application is developed, the core of critical code is important for its complete functionality. Any bug in such code has a more considerable negative impact than other parts of code, like data loss and exposure. Therefore, criticality is a high-level risk and requires testing efforts to lower the risk of such events.
• Churn: In risk assessment, “Churn” refers to the number of changes or code modifications made to any software application component. This indicates that the components of software applications that undergo lots of changes and updates are more likely to encounter bugs. Therefore, areas with high amounts of churn are high-risk levels and require thorough risk assessments and testing to ensure the application is free from errors or bugs.
• Complexity: Code complexity in software applications is considered a high-risk factor as they are more likely to have errors than simpler code. Considering all the possible paths in a function is a way to measure code complexity. Thus, functions with more paths will require more test cases to run tests, which shows more complexity and is prone to error. When assessing the risks associated with an application, it's important to consider the code's complexity.

Types of Risk During The Software Development Process

Understanding the type of risks that directly can impact the quality of software applications and identifying potential problems is crucial. Type of risks can be broadly classified into two types:

• Positive risk: These events potentially have better deals in the future and a positive impact on software projects or goals. For example, investing in new projects and developing new software applications.
• Negative risk: These are the events that have a negative impact on a software project and bring huge losses, like issues in the team, economic recession, etc.

The negative risks pose a threat to the success of software projects. With risk based testing, you gain insight into these risks for mitigating them and ensuring the quality of the software application.

Following are the groups of negative risks encountered by the team during the software development process.

• Product risk: Such risk occurs due to the poor clarity and stability of the software application requirement and its complexity. This risk leads to the incongruity between the functionality of the software application and end-user expectations, resulting in an unsatisfactory user experience.
• Project risk: They are the risk caused due to external dependencies, including contractual issues, personal issues, and delays on the contractor’s side. Such risk impacts the budget, timeline, and delivery of software applications.
• Process risk: This risk is related to internal software application management, like inaccurate estimates, underestimation of project complexity and delays, and non-negotiable deadlines.

The testers must identify and mitigate the negative risk that could impact software applications' success.

Who Performs Risk Based Testing?

Testers play a crucial role in assessing the risks associated with the software application. They must conduct a comprehensive risk assessment outlining the proposed solution's testing approach. If the testing strategy is insufficient, the likelihood of critical software failures when the software is deployed in production will escalate.

Having a thorough understanding of the software application's risks allows testers to evaluate whether the software is ready to go live based on the business' perceived risks.

Risk based testing entails planning, designing, and executing testing operations based on the priority of the modules. The focus areas for assessing software application's risk should include the following areas:

• Prone to defects
• Business-critical functionality
• Frequently used features and functions
• Security functionality
• Areas of complexity
• New product changes.

By prioritizing the testing of these areas, testers can reduce the likelihood of software application failures in production and improve its quality.

Risk Based Testing Techniques

Risk based testing is broadly classified into two main testing techniques, which are light-weight and heavy-weight risk testing techniques. These techniques are subjective and require the skills and experience of the development and tester team.

Light Weight Risk Based Testing

This technique is related to risk analysis which is mainly formal and focuses on technical and business risks by considering their probability and the factor impacting them. Light weight risk based testing is considered lightweight because it does not involve a detailed analysis of all possible risks. It mainly addresses risk criticality, complexity, and other factors in software applications.

One of the main attributes of lightweight risk based testing techniques is that they focus on only two risk factors:

• Likelihood: It refers to the probability that a risk will occur.
• Impact: It refers to the severity of the consequences if the risk does occur.

Lightweight techniques depend on simple qualitative judgments and scales instead of using complex mathematical models to calculate risk. For example, a team might rate the likelihood of risk as high, medium, or low and the impact as severe, moderate, or minor. These ratings can then be used to prioritize testing efforts.

There are three types of lightweight risk based testing techniques:

• Product Risk Management (PRisMA): The technique allows easy identification and prioritization of critical risks lined with the software application. It will ensure the software application’s risks are managed throughout its development life cycle. PrisMa involves several strategies that include risk reduction, risk avoidance, risk transfer, and acceptance. Along with this, continuous monitoring and review of the software applications are done to ensure risks are managed effectively.
• Pragmatic Risk Analysis and Management (PRAM): The technique involves evaluating the risk linked with the software application’s development and management, followed by implementing strategies to fix those risks. It involves prioritization of risks and the development of a plan to address those. The plan mainly includes risk reduction, risk avoidance, and risk acceptance.
• Systematic Software Testing: The technique involves risk based testing in a structured and systematic manner followed by pre-defined processes and methods. It will help you to ensure that efforts given in the test efforts are consistent, repeatable, and comprehensive. It involves defining test objectives and goals, developing a test plan including the test approach and needed resources, and creating test cases that combine all software application functionality.

Heavy-Weight Risk Based Testing Techniques

Heavy-weighted risk based testing is an approach for testing software that concentrates on prioritizing testing activities according to the level of risk associated with various areas of the software application.

In this method, the testing team identifies the most critical areas of the software application with the highest potential for failure and focuses their testing efforts on those areas. This aids in ensuring that the most critical components of the software undergo thorough testing and that any potential issues are identified and addressed before release to users.

Heavy-weighted risk-based testing requires examining the software requirements, design, and architecture to detect potential risks and prioritize testing activities accordingly. The testing team may also refer to historical data and industry best practices to inform their risk assessment.

There are four main types of heavy-weight risk-based testing techniques:

• Cost of Exposure: It measures the financial impact that could result from an identified risk on software applications. The Cost of Exposure can be calculated based on the probability of risk taking place by the potential cost of negative impact. It mainly determines three factors:
• The percentage of failure is related to the risk associated with the software application.
• Cost of loss related to typical failure to risk in production.
• Cost of testing.
• Failure Mode And Effect Analysis (FMEA): It is the technique used to detect quality risk items in software applications which are known as failure modes. You can identify where and how the software application under risk-based test might fail and assess the relative impact of the different failures.

It involves analyzing each component or step in the process to identify potential failure modes, their effects, and the likelihood of occurrence. FMEA helps identify high-risk areas and prioritize actions to prevent or mitigate potential failures.

The steps of FMEA involve the following:

• Failure modes: What could fail?
• Failure causes: Why does failure happen?
• Failure effects: What is the outcome of each failure?
• Quality Functional Deployment (QFD): This systematic process is utilized to translate end-user needs and requirements into particular designs and production goals in software development. It considers the quality risk that might arise from an incorrect and insufficient understanding of the end-user requirements. This is accomplished by focusing on the function of execution of the quality plan in software application development.
• Fault Three Analysis (FTA): The technique is used to identify the cause and effect of system failures. It involves creating a tree-like diagram representing the failure modes and their causes and then analyzing each potential cause to identify the most likely root cause.

It considers both observed failures raised from testing or production and potential failure rise from quality risks. Such failures are then subjected to root cause analysis which starts from defects causing failure, then with errors causing the defect, and continuing on identifying the root cause.

Which Risk Based Testing Technique to Choose?

The software testing technique in risk based approach depends upon the product, process, and project considerations. Quality risk analysis is integrated early in every sprint for Agile undertakings, and risks are cataloged alongside user story tracking. A precise estimate of test effort is crucial to successful project culmination.

For a complex system of systems, risk analysis is required for each individual system and the system of systems in its entirety. Projects that are mission-critical or safety-critical necessitate higher levels of formality and documentation in their risk based testing techniques. This method can be utilized at any phase, including user acceptance testing.

The essential component for effective risk based testing is the involvement of the appropriate team of stakeholders in risk identification and evaluation. These stakeholders usually fall into two groups: business and technical stakeholders. Every stakeholder brings their distinct perspective on what constitutes quality for the product and their priorities and concerns regarding quality.

Phases of Risk Based Testing

Risk based testing involves a series of steps that must be followed to test a software application successfully. Below are the steps explained in detail:

• Risk Identification

The first step in risk based testing involves identifying the potential risk associated with software applications. You can identify the risk by various means. Some of those are

• Expert interviews
• Independent assessments
• Project retrospectives
• Risk workshops
• Checklists
• Brainstorming sessions
• Past testing experiences
• Delphi techniques
• Cause and effect diagrams
• Root cause analysis

It is crucial to have clear communication amongst the development team who have encountered any potential risk in the past. This will help to understand the vulnerable area in the software application development, which could impact its functionality and performance. Along with this, the team also analyzes the requirements, design specifications, and documentation to identify potential risks.

• Risk Register

At this phase, a risk spreadsheet is maintained where identified risk is further divided into sub-risks called risk breakdown. Risk breakdown structure is a hierarchical representation of the list of identified risks organized by categories and sub-categories. This helps easy identification, analysis, and communication of software project risk to the stakeholders.

Registering the risk in a spreadsheet allows for tracking and monitoring risks throughout the software development process. You can identify the risk-prone area that eases resource and time allocation for risk management.

Here is an example of a risk breakdown structure, as shown in the below illustration. Typically it categorizes risk as external (associated with the market, legal and regulatory factor) and internal (associated with project management, technology, and resources). However, other than this, the risk associated with environmental and safety factors are also considered. Further, those risks are also subdivided into specific risks, which are then critically assessed.


• Risk Assessment

When the risk is identified and sorted, risk assessment begins. However, risk assessment can also go parallel with risk registration to identify the likelihood and impact associated with each risk. In some cases, risk assessment also occurs during identification using a checklist.

Here the risk is again categorized into appropriate types like performance, reliability, etc. Some organizations use ISO 25000 quality characteristics for categorizing. However, many others use different categorizing schemes.


• Risk Analysis

After potential risk is listed and categorized based on assessment, they are analyzed and filtered using quantitative and qualitative risk analysis methods. However, it is important to know about the factor impacting the likelihood of risk and the factors influencing the impact of risk. Here are those:

Factors impacting the likelihood of risk:

• Complexity of the software applications.
• Conflict in the team.
• Geographically distributed team.
• Software testing tools and technologies.
• Weak managerial.
• High earlier defect areas.
• Lack of early quality assurance activities.

Factors leading to the impact of risk:

• Frequency of use of impacted features of software applications.
• Loss of business.
• Loss of license.
• Safety.
• Damage to reputation.

The main objective of risk analysis is to differentiate between high-value and low values test cases to assign priority value. This involves the following steps:

Step 1: Using 3X3 Grid

In this method, the development team assesses each functionality and non-functionality of the software applications and associated test cases for likelihood or failure and the impact of failure.

The likelihood of failure of each functionality is analyzed by technical experts and categorized as likely, quite likely, and unlikely to fail.

The impact of the failure of such functionality is categorized as minor, visible, and interruption.

Step 2: Likelihood and Impact of Failure

The likelihood and impact of each identified risk are assessed and rated as either low, medium, or high likelihood, and minor, moderate, or severe impact. The resulting values position the corresponding test cases on a 3X3 grid.

To quantify the likelihood and impact, multiply the two values to calculate the risk priority number. However, in most cases, the risk level is also analyzed qualitatively, and the technique involved is Risk Matrix. This is used to find the probability and effect of risk.

Prioritization and Risk Assessment Matrix:

The risk rating measures the potential impact of risk and is calculated by multiplying the probability of the risk occurring by the severity of its consequences. This formula is commonly expressed as

Risk Rating = Probability x Severity

The prioritization and Risk Assessment Matrix is leveraged to evaluate the probability and severity of each recognized risk, also called the probability impact matrix; this matrix provides a quick overview of the risks and their corresponding priorities.

The likelihood and severity of the ambiguous circumstance are multiplied to gauge the risk rating. Probability is a percentage and can be classified as follows based on the possibility of the event happening:

• Frequent (91 – 100%)
• Probable (61 – 90%)
• Occasional (41 – 60%)
• Remote ( 11 – 40%)
• Improbable (0 -10%)
• Eliminated (0%)

Severity is evaluated on a scale of 1 to 4 and can be classified as Catastrophic, Critical, Marginal, or Negligible based on the event's impact.

Afterward, the resulting risk rating is applied to assign the risk to one of the four priority categories: Serious, High, Medium, or Low. These priority categories are charted against the severity and probability of the risk, as shown in the below matrix.

By utilizing the Prioritization and Risk Assessment Matrix, software development teams can promptly detect and prioritize risks, permitting them to concentrate their testing efforts on the most crucial areas of the software. This ensures that possible issues are resolved early in the development process, diminishing the probability of defects or failures and elevating the software's overall quality.

After assessing the risk level of each test case, the Risk Assessment Matrix, utilizing the probability and impact of failure, positions them on a 3x3 grid to determine their priority. This method enables the identification of high and low-value tests.

Step 3: Testing Priority Grid

This methodology involves the creation of a Testing Priority Grid based on the positioning of the test cases in the 3X3 grid outlined in Step #2.

The tests are prioritized and labeled with priority numbers 1, 2, 3, 4, and 5 based on the risk ratings assigned in Step #2. Tests with the highest risk ratings are assigned priority 1 and are situated in the top right corner of the grid, while the lower priority tests are given higher numbers.

After priority numbers sort the test cases, they are executed according to the order of priority. Tests with the highest priority are executed first, as they pose the greatest risk to the project. In contrast, lower-priority tests may be executed later or even removed if necessary.

Using the Testing Priority Grid, the testing team can prioritize their testing efforts based on the potential impact of each identified risk, ensuring that the most important tests are conducted first, and potential risks are addressed early in the development process. This approach is designed to improve the overall quality of the software and reduce the likelihood of defects or failures.

Step 4: Details of Testing

In the fourth stage of the testing process, the emphasis is on determining the appropriate degree of detail for testing based on the prioritization of the test cases. Tests assigned a higher priority ranking, denoted by a value of 1, are deemed “More Thoroughly” and thus require a more comprehensive level of testing. To ensure that these high-priority features and their associated test cases are tested to a high standard, proficient testers must be assigned to the task.

The same approach is taken for test cases with priority rankings of 2, 3, and 4; however, the level of detail involved in testing these cases may be reduced compared to those with a higher priority ranking. Finally, for test cases with a priority ranking of 5, a decision may be made to de-scope these features and tests based on the time and resources available. This implies that these test cases may need to be tested or receive minimal testing.

Risk Response Planning

It involves thoroughly analyzing the identified risks to determine if a response is necessary. The risk owner will assess whether it requires action during the project planning or monitoring phase or can be left unattended.

If the risk demands a response, the risk owner will evaluate various options to minimize the probability and impact of the risk on the project. These options include adjusting the project plan to eliminate the risk, allocating additional resources to mitigate the risk, or modifying the testing strategy to concentrate on the areas of the project most affected by the risk.

The primary objective of risk response planning is to minimize the impact of risks on the project and ensure that the project is completed successfully within the desired time and budget constraints.

Risk Mitigation

Risk mitigation involves taking measures to decrease the risk's possibility and/or impact. It can be done by eliminating or lowering the risk to an acceptable level. Risk mitigation aims to reduce the likelihood of any potential harm caused by these risks in the software applications and ensure that the establishment is adequately equipped to tackle any unforeseen circumstances.

There are many ways to mitigate risks. For example, an organization could implement safety protocols, establish redundant systems, train employees to handle emergency situations, or invest in insurance coverage. By taking these measures, the establishment can minimize the impact of potential risks and deter them from metamorphosing into significant predicaments.

Risk Contingency

Risk contingency concerns the probability of an unanticipated event with an indeterminate or unforeseeable impact. A contingency plan, or an action plan or backup plan, is a calculated measure to brace for worst-case scenarios. The purpose of a contingency plan is to ascertain what measures can be taken for an unpredictable event, such as a natural calamity, cyber assault, or supply chain disruption.

Risk Monitoring and Control

Risk monitoring and control processes are utilized to track the identified risk, monitor the residual risks, detect new risks, evaluate the change, execute the response plan, and monitor risk triggers. The primary purpose of this step is to effectively manage the risk throughout the software project and business process.

You can use several techniques and tools in risk monitoring and control, like risk assessments, risk audits, variance, and trend analysis, retroactive meetings, etc. when you implement these techniques; you will be able to manage the risks and ensure that the preparedness to respond to potential issues on time.