Infection is a mutation testing framework designed specifically for PHP, a popular programming language used for web development. Mutation testing is a technique used to evaluate the effectiveness of a test suite by introducing small, artificial changes (mutations) into the source code and checking if the tests can detect these changes. In other words, it helps developers identify weaknesses in their test cases.
Here’s a more detailed explanation of Infection:
- Purpose: Infection aims to improve the quality of test suites by identifying areas where tests may be insufficient or ineffective at catching bugs. It does this by introducing mutations into the codebase and checking if the tests can detect these mutations.
- Mutation Generation: Infection generates mutations by applying various modifications to the source code, such as changing operators, swapping variable values, or removing conditional statements. These mutations simulate potential bugs or errors that could occur in the code.
- Test Execution: After generating mutations, Infection runs the existing test suite against each mutated version of the code. If a mutation causes a test to fail, it indicates that the test suite is effective in detecting that particular mutation.
- Metrics and Reports: Infection provides metrics and reports to help developers understand the effectiveness of their test suite. This includes information on mutation coverage (the percentage of mutations detected by tests) and detailed reports on individual mutations and their outcomes.
- Integration with Continuous Integration (CI): Infection can be integrated into the continuous integration process, allowing developers to automatically run mutation testing whenever code changes are made. This helps ensure that any regressions introduced by new code are quickly identified and addressed.
- Feedback Loop: By highlighting areas where tests are lacking or ineffective, Infection provides valuable feedback to developers, enabling them to improve their test suite and ultimately produce more reliable and bug-free software.
infection Command Examples
1. Analyze code using the configuration file (or create one if it does not exist):
# infection
2. Use a specific number of threads:
# infection --threads [number_of_threads]
3. Specify a minimum Mutation Score Indicator (MSI):
# infection --min-msi [percentage]
4. Specify a minimum covered code MSI:
# infection --min-covered-msi [percentage]
5. Use a specific test framework (defaults to PHPUnit):
# infection --test-framework [phpunit|phpspec]
6. Only mutate lines of code that are covered by tests:
# infection --only-covered
7. Display the mutation code that has been applied:
# infection --show-mutations
8. Specify the log verbosity:
# infection --log-verbosity [default|all|none]
Summary
Overall, Infection is a powerful tool for PHP developers looking to enhance the quality of their test suites and ensure better code coverage. By systematically introducing mutations and evaluating test effectiveness, it helps identify potential weaknesses in the codebase and improve overall software quality.