What are the best practices for writing test cases and scenarios for a system design?

In my experience, people tend to underestimate the importance of identifying clear and well-defined test objectives before diving into writing test cases and scenarios. This oversight can lead to a cascade of extra work and frustration down the line. The truth is, it's virtually impossible to identify every testing aspect right from the beginning. As systems evolve and projects progress, new requirements, features, and nuances emerge. That's why it's crucial to view test objectives as a continuous work in progress.

I think the basics were kind of neglected here: boundary-value analysis and equivalence class partitioning should be employed whenever applicable.

Be Specific and Clear: Avoid ambiguity. Use a Standard Format: Use a standard template for writing test cases (include fields like: Test Case ID, Description, Pre-conditions, Steps, Expected Results, and Actual Results) Include Positive and Negative Cases: Test not just for the "happy path" but also for failure conditions. Identifies behavior with unexpected conditions. Parameterize Test Cases: Write test cases that can be reused for different data sets. Useful for functional and regression testing. Modularize Test Cases: Break down complex test scenarios into smaller, manageable test cases. Easier to maintain and update the test suite. Write Setup and Teardown Steps: Steps needed before the test and any steps for cleaning up.

i think one should aim to have a minimum amount of test possible, that still check all relevant flows and scenarios. one should bare in mind that test require maintenance and debug. in order to do, test should be as generic as possible and also to have a well-defined purpose.

To put it simply, well-designed test cases and scenarios are not just a box-ticking exercise. They're like the secret sauce that makes testing work.

Test design should be revisited at each test run. As the software evolves, so do the testing requirements. It's an ongoing process that ultimately leads to a more robust and reliable end product.

also, it is very important to make sure the test is actually doing what is meant to do. it is generally true right after we write the test, but not always true when system design changes. in the case the test fails - we can a trigger and provide a fix, but the test can also pass without providing any desired outcome. we should aim for precise checking, not passing the tests.

Also, it's important to ask for clarification even if the test passed but with different behavior. Details that seem to not be important usually add up and are not so easy to track in the future.

Automate Where Possible: Automate test cases that are repetitive and need to be executed frequently. This saves time and ensures consistency. Version Control: Use version control systems to keep track of changes to test cases, just like you would for source code. Documentation: Keep detailed documentation for each test case, including the purpose, the setup required, and any specific data or tools used.

Automation and live documentation should be a minimum requirement for a successful testing approach. Also, don't settle and try to find ways to test your testing approach and improve whenever time allows it.