Answer.

Manual testing of multi-user scenarios involves checking systems where multiple users interact with the same functionality or data simultaneously (e.g., chats, collaborative document editing, online stores with shopping carts). This is crucial for ensuring data integrity and preventing conflicts.

Background: With the development of network applications and cloud services, many simultaneous access scenarios have emerged. Simple mistakes can lead to data loss, duplication, or incorrect data representation, so attention to such tests has significantly increased.

Problem: Simultaneous manual testing requires coordinated actions from multiple testers or the emulation of real multi-user behavior. The lack of automation or support from developers complicates the task.

Solution: For effective manual testing, it is necessary to:

Prepare test user sets with different permissions and roles.
Write scenarios where the actions of one user can affect the data or state of the interface for another user.
Coordinate the work of several testers or use parallel browsers/devices.
Pay special attention to collisions when editing the same data, locks, system notifications, and transaction conflicts.
Record precise sequences of actions and timing of operations.

Key features:

Testing from different browsers, devices, and sessions.
Working with an administrator role and a regular user simultaneously.
Special scenarios with simultaneous attempts to edit or delete.

Trick Questions.

Is one tester enough for complete coverage of multi-user scenarios?

No. It is better to coordinate a team of testers or use parallel sessions on multiple devices/browsers.

Can all scenarios be tested using only emulators or mock data?

No. Real multi-user behavior is difficult to fully emulate without the participation of several live clients or users.

Is it necessary to create special users for each test?

Usually yes: it helps avoid data collisions and increases test repeatability.

Common Mistakes and Anti-Patterns

Using a single account for different users in tests.
Neglecting race-condition scenarios and conflicts when saving data.
Failing to record the exact sequence of actions.

Real-Life Example

Negative Case

Two testers used one account to check the store's shopping cart: as a result, the bug regarding the cart clearing went unnoticed.

Pros:

Less time spent on registering test users.

Cons:

Hidden defects during data synchronization.
The bug manifested only in production.

Positive Case

Separate test accounts were created, and step-by-step scenarios with exact timing of actions were documented.