Test case prioritization is the process of assigning a priority to each test case in a test suite. This is important in large automation suites, where there are often hundreds or thousands of test cases. By prioritizing test cases, you can ensure that the most important and critical test cases are executed first. This can help to improve the efficiency of the testing process and reduce the risk of defects being released into production.
Test Case Prioritization Factors
There are many different factors that can be considered when prioritizing test cases, such as:
- Risk of failure:
This is the likelihood that a test case will fail. Test cases that are more likely to fail should be prioritized higher because they pose a greater risk to the software. The risk of failure can be determined by factors such as the complexity of the test case, the history of defects in the software, and the experience of the testers. - Importance of the functionality:
This is the impact that a test case has on the functionality of the software. Test cases that cover critical functionality should be prioritized higher because they are more important to the overall quality of the software. The importance of the functionality can be determined by factors such as the business value of the functionality, the number of users who will use the functionality, and the impact of a defect in the functionality. - Cost of testing:
This is the resources required to execute a test case. Test cases that are more expensive to test should be prioritized lower because they can take up more time and resources. The cost of testing can be determined by factors such as the complexity of the test case, the number of resources required to execute the test case, and the cost of those resources. - Time available for testing:
This is the amount of time available to test the software. Test cases that can be executed quickly should be prioritized higher because they can be completed within the available time. The time available for testing can be determined by factors such as the deadline for the software release, the number of test cases to be executed, and the resources available for testing. - Availability of resources:
This is the availability of the resources needed to execute a test case. Test cases that require specialized resources should be prioritized lower because they may not be available when needed. The availability of resources can be determined by factors such as the availability of testers, the availability of test equipment, and the availability of the software under test.
Strategies for Test Case Prioritization
There are many different strategies that can be used for test case prioritization. Some of the most common strategies include:
- Risk-based prioritization:
This strategy prioritizes test cases based on the risk of failure. Test cases that are more likely to fail are prioritized higher. For example, a test case that covers a new feature that has not been tested before would be prioritized higher than a test case that covers a well-established feature.
| Test case | Description | Risk of failure | Priority |
|---|---|---|---|
| TC-1 | Test the login functionality | Low | Low |
| TC-2 | Test the checkout functionality | High | High |
| TC-3 | Test the search functionality | Medium | Medium |
- Requirement-based prioritization:
This strategy prioritizes test cases based on the importance of the functionality they cover. Test cases that cover critical functionality are prioritized higher. For example, a test case that covers a functionality that is required by a customer would be prioritized higher than a test case that covers a functionality that is not required by a customer.
| Test case | Description | Importance | Priority |
|---|---|---|---|
| TC-1 | Test the login functionality | Critical | High |
| TC-2 | Test the checkout functionality | Important | Medium |
| TC-3 | Test the search functionality | Not important | Low |
- Coverage-based prioritization:
This strategy prioritizes test cases based on the amount of code or functionality they cover. Test cases that cover more code or functionality are prioritized higher. For example, a test case that covers a complex function would be prioritized higher than a test case that covers a simple function.
| Test case | Description | Code coverage | Priority |
|---|---|---|---|
| TC-1 | Test the login functionality | 100% | High |
| TC-2 | Test the checkout functionality | 80% | Medium |
| TC-3 | Test the search functionality | 50% | Low |
- Cost-based prioritization:
This strategy prioritizes test cases based on the cost of testing them. Test cases that are more expensive to test are prioritized lower. For example, a test case that requires specialized equipment would be prioritized lower than a test case that does not require specialized equipment.
| Test case | Description | Cost of testing | Priority |
|---|---|---|---|
| TC-1 | Test the login functionality | 100 | Low |
| TC-2 | Test the checkout functionality | 200 | Medium |
| TC-3 | Test the search functionality | 300 | High |
- Time-based prioritization:
This strategy prioritizes test cases based on the time available for testing. Test cases that can be executed quickly are prioritized higher. For example, a test case that can be automated would be prioritized higher than a test case that must be executed manually.
| Test case | Description | Time to execute | Priority |
|---|---|---|---|
| TC-1 | Test the login functionality | 1 hour | Low |
| TC-2 | Test the checkout functionality | 2 hours | Medium |
| TC-3 | Test the search functionality | 3 hours | High |
How to Prioritize Test Cases in Large Automation Suites
Following are the steps on how to prioritize test cases in large automation suites, using the example of an e-commerce website:
TC-1: Test the login functionality
TC-2: Test the checkout functionality
TC-3: Test the search functionality
TC-4: Test the registration functionality
TC-5: Test the forgot password functionality
TC-6: Test the Contact Us functionality
- Start by identifying the most important and critical test cases:
These are the test cases that are most likely to fail and that have the biggest impact on the functionality of the software. For example, the login functionality is a critical functionality of an e-commerce website, so TC-1 (test the login functionality) would be considered a critical test case.
The following are some of the factors that can be considered when identifying the most important and critical test cases:
- Risk of failure: Test cases that are more likely to fail should be prioritized higher. For example, TC-1 (test the login functionality) is more likely to fail than TC-6 (test the contact us functionality).
- Importance of functionality: Test cases that cover critical functionality should be prioritized higher. For example, TC-1 (test the login functionality) covers critical functionality than TC-6 (test the contact us functionality).
- Cost of testing: Test cases that are more expensive to test should be prioritized lower. For example, TC-5 (test the forgot password functionality) is more expensive to test than TC-6 (test the contact us functionality).
- Customer impact: Test cases that have a high impact on customers should be prioritized higher. For example, TC-1 (test the login functionality) has a high impact on customers than TC-6 (test the contact us functionality).
Based on these factors, the following test cases would be considered the most important and critical:
- TC-1: Test the login functionality
- TC-2: Test the checkout functionality
- TC-3: Test the search functionality
- Use a prioritization matrix to help you rank the remaining test cases:
The prioritization matrix should include the factors that are most important to you, such as the risk of failure, the importance of the functionality, and the cost of testing. For example, a test case that has a high risk of failure and is also important to the functionality of the software would be given a higher priority than a test case that has a lower risk of failure but is not as important to the functionality.
The following is a prioritization matrix that can be used to rank the remaining test cases:
| Test case | Risk of failure | Importance of functionality | Cost of testing | Priority |
|---|---|---|---|---|
| TC-4: Test the registration functionality | Medium | Low | Low | Low |
| TC-5: Test the forgot password functionality | High | Medium | Medium | Medium |
| TC-6: Test the contact us functionality | Low | Low | Low | Low |
Based on this prioritization matrix, the following order of priority can be determined:
- TC-1: Test the login functionality
- TC-2: Test the checkout functionality
- TC-3: Test the search functionality
- TC-5: Test the forgot password functionality
- TC-4: Test the registration functionality
- TC-6: Test the Contact Us functionality
- Once you have ranked the test cases, you can start to create a test plan:
The test plan should specify the order in which the test cases will be executed. For example, the test plan might specify that TC-1 (test the login functionality) and TC-2 (test the checkout functionality) should be executed first, followed by the remaining test cases.
The following is a test plan that specifies the order in which the test cases will be executed:
- Day 1: TC-1, TC-2
- Day 2: TC-3, TC-5
- Day 3: TC-4, TC-6
This test plan ensures that the most important and critical test cases are executed first.
These are just a few of the steps involved in prioritizing test cases in large automation suites. The specific steps involved will vary depending on the specific project. However, the general principles outlined here can be applied to any project.
Importance of Test Case Prioritization
Here are some of the importance of test case prioritization in large automation suites:
- Improves efficiency:
By prioritizing test cases, you can focus your testing efforts on the most important and critical test cases. This can help to save time and resources, and it can also help to reduce the risk of defects being missed. - Reduces risk:
By prioritizing test cases, you can ensure that the most important and critical test cases are executed first. This can help to reduce the risk of defects being released into production, which can save you time and money in the long run. - Improves quality:
By prioritizing test cases, you can ensure that the most important and critical functionality is tested thoroughly. This can help to improve the quality of the software and reduce the number of defects that are found after the software is released. - Increases confidence:
By prioritizing test cases, you can increase your confidence in the quality of the software. This can help to reduce the risk of customer dissatisfaction and it can also help to improve your reputation as a software developer.
Conclusion
Test case prioritization is an important part of any software testing process. By prioritizing test cases, you can ensure that the most important and critical test cases are executed first. This can help to improve the efficiency of the testing process and reduce the risk of defects being released into production.