How to Design Tests? Weakening the pre-condition!
Understanding the Importance of Testing
The Need for Testing
- Discusses various methods to implement different types of tests and emphasizes the importance of understanding how to create these tests.
- Highlights the distinction between writing tests correctly and prioritizing which tests are most important.
Sources for Test Creation
- Identifies two primary sources for test creation: specifications and bug reports from users encountering issues in the system.
- Explains that testers can also analyze code to identify complex situations that require testing, focusing on ensuring proper implementation.
Prioritization in Testing
- Stresses that testers must prioritize their focus due to time constraints, emphasizing relevance based on potential impact on stakeholders.
- Notes that complex functionalities should be tested thoroughly as misunderstandings during implementation can lead to significant issues.
Key Principles in Writing Tests
Focusing on Relevant Tests
- Emphasizes the principle of focusing on writing relevant tests that exercise behavior under complex states or conditions.
Weakening Preconditions
- Introduces the concept of weakening preconditions, allowing functionality to be tested across various states rather than a single specific state.
- Suggests increasing input states enhances test suite reliability by covering more scenarios.
Representing Edge Cases
- Recommends testing edge cases (e.g., empty arrays, full arrays, half-filled arrays), ensuring comprehensive coverage of possible inputs.
Understanding Test Input Variability
Importance of Diverse Test Inputs
- The discussion emphasizes the necessity of testing with various combinations of concepts to ensure that students pass based on average performance, highlighting the importance of edge cases in testing scenarios.
- It is noted that increasing coverage for representative cases while avoiding redundancy is crucial. Testing with a single human input may suffice, suggesting that not all combinations are necessary.
- The speaker argues against excessive redundancy in test inputs, indicating that testing with two or three similar inputs may not yield significant differences and could weaken preconditions.
Multidimensional Input Considerations
- The conversation shifts to the multidimensional nature of input spaces, stressing that test inputs should consider more than just method arguments; initial system memory states also play a role.
- Variability in hardware and operating systems is discussed as critical factors affecting system performance. A system might work well on one device but fail on another due to these differences.
Browser and Environment Variables
- The need to account for different browsers and their configurations is highlighted. Specific browser settings can significantly impact how a system operates during tests.
- Auxiliary libraries and environmental variables must be considered as they can alter system behavior. Properly defining these variables ensures consistent test results across different environments.
Impact of System Features
- Optional features within systems can lead to variations in behavior. Testing must encompass these variations, especially when creating software product lines tailored for different clients.
- The existence of auxiliary processes like Travis CI can influence class-specific tests, necessitating adjustments in testing strategies based on network latency and notification behaviors from the system.
Comprehensive Test Input Strategy
- Overall, it’s emphasized that test inputs extend beyond mere parameters; they include broader considerations such as available files and environmental conditions which affect outcomes.