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It’s very important to be able to analyze flaky tests if you are working as a software tester since any automated tests that have unclear results will constantly slow the speed of overall development down.

Even if you have never worked with flaky tests, this article will still be very useful for you since it describes a completely systematized set of reasons why instability happens inside test suites.

Why does instability happen?

  • Due to tests directly;
  • Due to an incorrect set of frameworks used to launch such tests;
  • Due to a set of services and libraries that control test activation;
  • Due to the OS and other technical components that directly affect a process of interaction between frameworks and automate tests.

Further, we’ll try to describe the basic criteria for the reasons why everything mentioned above can be flaky.


Don’t be surprised if something happens with tests – it happens permanently. The reasons why they fail are usually:

  1. Incorrect initialization or clearance;
  2. Incorrectly selected test information;
  3. Incorrect suggestions about a current state of a system;
  4. Direct dependence on unsynchronized actions;
  5. Dependence on the sequence of the test launch.

An incorrect set of frameworks used to launch testing

Possible problems can happen due to the following reasons:

  • The impossibility of giving sufficient resources for a system you are testing;
  • Incorrect test planning (when there is a conflict between tests);
  • A small part of system resources doesn’t allow you to start meeting the requirements.

A set of services and libraries that control test launch

A system that is being tested or additional software can be the source of the problems themselves. For example, the software can have much dependence on third-party services that, in turn, contain incorrect configurations and other technical problems.

Possible problems:

  • Uninitialized variables;
  • RAM leakage;
  • No response from a server;
  • Possible redundancy of subscriptions to a resource;
  • Updating an application with different speed for its different versions.

Tip: testing environment you are using should be completely closed since this type of environment is less exposed to instability.

OS and other technical components

Your operating system and hardware can be the source of test instability. The problems may happen due to the following reasons:

  • An unstable network;
  • Disk errors;
  • A resource is used to do other tasks that are not directly connected with test execution.


To sum up, there are numerous types of failures, therefore, it’s not easy to seek a reason for instability during the test launch.

This article can help to localize the defects in a product quality assurance organization and also, analyze their nature to prevent future failures.

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