Answer.

Checklists are a set of brief formalized items that a tester sequentially performs to verify an application. They serve to structure testing, ensure reproducibility, and minimize omissions.

History of the issue:

Checklists in testing emerged as a simple tool for describing those aspects of the system that need to be verified, often for regression testing or checking "critical" paths of user flows.

Problem:

Most often, errors occur due to overly superficial items ("Check authorization"), forgotten important scenarios, confusion in checklists, and their obsolescence. Also, using long checklists results in a loss of testing flexibility.

Solution:

Before creating a checklist, analyze business processes and use scenarios
Allocate separate items for each requirement
Formulate items clearly ("Check the display of an error when entering an incorrect password")
Regular updating and revision of the list
Use checklists as a basis for communication with the team

Key features:

Structuring the testing process — checklists organize work and reduce the likelihood of omissions
Ease of making changes and additions — checklists are easier to maintain than test cases
Quick onboarding of new team members with the product — checklists help quickly get up to speed on the project

Tricky questions.

Can checklists be considered a replacement for test cases in any situation?

No, checklists are usually used for simpler or repetitive checks, where detailed steps are not required, while detailed test cases are suitable for complex or critical functionality.

Must checklists always be detailed for every step?

No, the level of detail depends on the purpose: for an experienced team — briefly, for new employees — in more detail.

Is it true that one universal checklist is enough for any release?

No, checklists quickly become obsolete. They need to be refactored and adapted to real changes in the product.

Typical mistakes and anti-patterns

Copying checklists without adapting them to new functionality
Not revising checklists after product development or refactoring
Overloading checklists with excessive detail

Example from real life

Negative case

The team uses the same checklist for all releases, not updating it for a year. As a result, significant changes in functionality go unaddressed, and a critical bug goes into production.

Pros:

Time savings in preparation

Cons:

Omitting important changes
Increased number of incidents in "production"

Positive case

The tester updates the checklist after each enhancement, coordinates changes with developers, and sets a checklist revision process for each sprint.