How to Design Tests? Strengthening the post-condition!
Understanding Post-Conditions in Testing
Strengthening Post-Conditions
- The concept of strengthening post-conditions is introduced, emphasizing the importance of establishing conditions that must be satisfied after an action is performed.
- A weak test may only provide superficial evidence of system behavior; thus, it’s crucial to enhance these checks for more robust validation.
Enhancing Test Validity
- An example illustrates a basic verification method: checking if a report file (report.pdf) exists and is not empty as a post-condition check.
- To improve this verification, one should ensure that the PDF file is valid and not corrupted, which could indicate deeper issues with functionality.
Detailed Verification Levels
- Further enhancement involves confirming specific content within the PDF, such as ensuring it meets client requirements (e.g., no page numbering).
- The discussion highlights different levels of verification, where stronger checks yield more solid evidence regarding expected outcomes.
Balancing Pre and Post Conditions
Reducing Possible States
- The goal is to reduce possible states that satisfy post-conditions by adding more rules or constraints.
- Weakening preconditions allows testing across a broader range of inputs while strengthening post-condition checks narrows down potential final states.
Types of Testing Strategies
- There’s an emphasis on balancing various types of tests (unit tests, integration tests), each serving distinct purposes depending on the system's context.
Independence in Testing
Importance of Test Independence
- Each test should operate independently without relying on previous tests' execution or state configurations.
- Tests must assume a fresh start for the system to avoid side effects from prior executions impacting results.
Challenges with Dependencies
- Dependencies between tests complicate execution; for instance, if deletion relies on insertion being executed first, it creates challenges in isolating issues during debugging.
Managing Test Suites Effectively
Compositionality in Tests
- Maintaining compositionality ensures ease in creating new test suites without complex dependencies hindering flexibility.
Practical Implications
Efficiency in Process Preparation
Importance of Efficient Steps
- The discussion emphasizes the need for efficiency, particularly in preparing a specific step to set up for the next state. This preparation involves gathering information that can be utilized to implement checks or actions more effectively.
Regression Testing Principle