Answer.

Creating test cases is one of the fundamentals of manual testing and a key step in verifying the application's functionality.

Background: For a long time, test cases have been the central method of quality control: they allow structuring the requirements check and guarantee test repeatability regardless of tester changes.

Problem: The main difficulty is finding a balance between excessive detail and insufficient elaboration. Overly detailed cases make testing routine and slow, while too concise ones may miss important scenarios. Common issues include:

Insufficient linkage to requirements.
Missing edge cases.
Scenario duplication.
Obsolescence due to product changes.

Solution: For an effective test case, it is necessary to:

Establish a connection of each test to the requirements (traceability matrix).
Use test design techniques (equivalence partitioning, boundary value analysis).
Conduct regular audits and updates of test cases.
Involve the development team and analysts to clarify complex points.

Key features:

Structuring based on the principle "one test — one expected result".
Updating with changes in requirements.
Covering all paths, including negative cases.

Trick questions.

Are test cases always written before development?

No. Although it is desirable to write them before implementation (shift-left), in practice, test cases are often refined as new information comes in or after the testing environment is established.

Should one test case check only one scenario?

Yes, the classic principle: "one test — one result" facilitates bug analysis and understanding of what was tested. Exceptions may be made for end-to-end scenarios, but it is still important to clearly differentiate expected outcomes.

Can test cases automatically generated from requirements be fully trusted?

No. Such cases are often superficial and may miss important business logic, boundary values, or action combinations — manual analysis is required.

Common mistakes and anti-patterns

Copying old cases without adapting them to new requirements.
Skipping negative scenarios.
Using vague formulations (for example, "the system works correctly").

Real-life example

Negative case

The team used old test documentation without revision and started using test cases that were not adapted to changed functionality.

Pros:

Time savings on creating new documents.

Cons:

New business rules were missed, bugs were discovered only after going into production.

Positive case

The tester reviewed the test cases, discussed challenging points with analysts, identified outdated ones, and conducted a review with the new team.