Why do test flags occur? Is it because of their services?

Flaky tests are unstable tests that sometimes pass and sometimes fail without any changes in the code. The main reasons for their occurrence:

• Dependence on external services that may be unavailable or operate with delays.
• Asynchrony and timing issues: tests do not account for response delays, leading to race conditions.
• Improper isolation of tests, where the state of one test affects another.
• Use of random data or data generation, leading to unpredictable results.

Thus, flaky tests can arise due to the instability of services, but more often the problem lies within the test itself — its architecture and synchronization. To reduce flakiness, it is important to stabilize the environment, mock external services, and properly wait for asynchronous operations.