Every QA/QE professional has encountered a flaky test at least once in their career. It may be a small, harmless bug that can be fixed in an instant, or it may take months to identify and fix it. This can be very costly and take a toll on your reputation and budget. Don’t you want to know why flaky tests exist, how to identify them at an earlier stage, or even avoid them? I’ll walk you through automated and manual UI testing. Join the investigation of web applications and their UI, and we will figure it out together with you to find out the origins and roots of common flaky tests; to explore real cases and their solutions; to learn good practices.

1. CONFIDENTIAL designator
V0000000
1
How to deal with them
Flaky Tests
Juri Solovjov
Software Quality Engineer
jsolovjo@redhat.com
Flaky
Tests
-
How
to
deal
with
them
juri-solovjov

2. Introduction
2
Juri Solovjov
▸ Software Quality Engineer
▸ 5+ years at Red Hat in Brno, Czech Republic
▸ Involved in integration middleware projects:
･ Hawtio, Camel Spring Boot, Camel Quarkus, Camel-K
▸ Side projects:
･ Red Hat Summer Camp Brno - an IT camp for high-school students
･ Leading a seminar on Tests in practice at Masaryk University in Brno

3. What we’ll discuss today
▸ What are Flaky Tests?
▸ Origins of Flaky Tests
▸ Good Practices
▸ Q&A
Agenda
3

4. CONFIDENTIAL designator
V0000000
4
What are Flaky Tests?

5. CONFIDENTIAL designator
V0000000
Flaky tests are defined as tests that
return both passes and failures
despite no changes to the code or
the test itself.
What are Flaky Tests?
5
Source:
https://www.jetbrains.com/teamcity/ci-cd-guide/concepts/flaky-tests/

6. What are Flaky Tests?
6
driver.navigate().to("https://www.google.com/");
driver.findElement(By.name("q")).sendKeys("SFSCon");
driver.findElement(By.cssSelector("[type=submit]")).click();
assertEquals(9, driver.findElement(By.cssSelector("#ires .g")).size());
To pass or to fail - that’s the question
Flaky Tests
Source:
https://selenide.org/blog.html

7. What are Flaky Tests?
7
▸ What can go wrong?
▸ Which line of the code may break the test?
To pass or to fail - that’s the question
Flaky Tests
Source:
https://selenide.org/blog.html

8. What are Flaky Tests?
8
driver.navigate().to("https://www.google.com/");
driver.findElement(By.name("q")).sendKeys("SFSCon");
driver.findElement(By.cssSelector("[type=submit]")).click();
assertEquals(9, driver.findElement(By.cssSelector("#ires .g")).size());
To pass or to fail - that’s the question
Flaky Tests
Source:
https://selenide.org/blog.html

9. What are Flaky Tests?
9
▸ 4 matching elements - 2 of them are hidden
▸ Possible fix is to modify the third line of the code
driver.findElement(By.name("btnK")).click();
To pass or to fail - that’s the question
Flaky Tests

10. What are Flaky Tests?
10
▸ However, the flakiness is still present
▸ When filling a search bar - the dropdown list hides the first search button and another one shows up
To pass or to fail - that’s the question
Flaky Tests

11. What are Flaky Tests?
11
One of the solution might be using a framework with smart built-in timeouts and retries
▸ In case of Selenide framework (free and open-source):
@Test
public void userCanLogin() {
open("https://www.google.com");
$(byName("q")).setValue("selenide");
$("[name=btnK]").click();
$$("#ires .g").shouldHave(size(10));
}
To pass or to fail - that’s the question
Flaky Tests
Source:
https://selenide.org/

12. CONFIDENTIAL designator
V0000000
12
Origins of Flaky Tests

13. Origins of Flaky Tests
13
There are many reasons why flaky tests may show up in your test pipelines
▸ Test Environment
･ Lack of memory and space, caching issues
･ Docker and Jenkins issues
▸ Connection
･ Requests and responses speed and their order
▸ Test Frameworks
･ Versions mismatch, dropped support, bugs
Flaky Tests

14. CONFIDENTIAL designator
V0000000
Test Frameworks
Origins of Flaky Tests
14

15. Origins of Flaky Tests
15
▸ TypeError: _.filter is not a function
▸ Nothing is clickable
▸ Affects only automation
▸ Unstuck only after refresh
▸ Manually works fine
Test Frameworks

16. Origins of Flaky Tests
16
The root cause:
▸ Updating to Selenium 4.12.0 caused the issue #12659 where Selenium overwrites _ sign
Test Frameworks

17. Origins of Flaky Tests
17
▸ It’s not always a good idea to blindly update all versions of frameworks in your project
･ Lost support (e.g. dropped java 8 support)
･ A new bug is introduced
▸ Version mismatch of frameworks is also a common issue
･ A new version may bring new requirements and changes in a code
Test Frameworks

18. CONFIDENTIAL designator
V0000000
Test Environment
Origins of Flaky Tests
18

19. Origins of Flaky Tests
19
Test Environment

20. Origins of Flaky Tests
20
Rebuild a job helped to get it passed
▸ However, the job was still failing and passing in a random order
What could go wrong?
▸ Lost Internet connection when pulling images or it met pulling limits
▸ Lost connection to a testing machine
▸ Lack of memory and space
▸ Error while building and deploying quickstarts for the app under test
▸ etc.
Test Environment

21. Origins of Flaky Tests
21
What actually happened
▸ An application deployed on OpenShift become unstable after a while
▸ Continuously stopping and restarting accompanied by the error Liveness probe failed
▸ The application’s pod on OpenShift didn’t show detailed error messages
Test Environment

22. Origins of Flaky Tests
22
It turned out that
▸ It was caused by the app’s pod exceeding its memory allocation on OpenShift
▸ The resources weren’t defined by default
What helped us is to edit app’s deployment configuration to increase the memory allocation
▸ spec:
resources:
limits:
cpu: "1"
memory: 100Mi
requests:
cpu: 200m
memory: 32Mi
Test Environment

23. Origins of Flaky Tests
23
▸ Clean up clusters, terminate unnecessary machines, remove namespaces/projects;
▸ Keep track of internal shared repositories, their space and do clean up jobs;
▸ Do not create machines with large resources for low-cost work;
Test Environment: Resources

24. Origins of Flaky Tests
24
▸ If you have pipelines in parallel using the same resources and sharing the same cluster
･ Avoid job deadlocks
･ Add checks, conditions, timeouts
Test Environment: Automation

25. Origins of Flaky Tests
25
▸ Connection is stable
▸ VPN is up
▸ Nothing is overloading network
▸ No outages are happening
Test Environment: Infrastructure

26. CONFIDENTIAL designator
V0000000
Application under test
Origins of Flaky Tests
26

27. Origins of Flaky Tests
27
Also, flaky tests occur due to changes such as new features or new bugs introduced by developers
▸ Performance
▸ Bugs in the application
▸ Runtimes
Application under test

28. Origins of Flaky Tests
28
▸ The loading order of the modules was not explicitly defined
▸ Sometimes, rendering of the page was faster than modules get loaded
▸ It caused a missing Logout button and therefore failures of the tests
Application under test

29. Origins of Flaky Tests
29
▸ A broken layout for drop-down menu
▸ Tests were mostly passing
▸ Tests are running in a background with no UI
▸ It required us to do a manual testing to find it
Application under test

30. CONFIDENTIAL designator
V0000000
30
Good Practices

31. Good Practices
31
▸ Consider test frameworks with built-in timeouts and smart retries
▸ Do not use common locators but unique ones
▸ Collaborate with developers
▸ Beware of version updates
Good Practices

32. Good Practices
32
▸ Keep an eye on infrastructure
･ Space, memory, hanging jobs and machines
▸ It’s always good to know your application under test
▸ Be familiar with the application infrastructure
･ To develop tests effectively with low cost
･ To decrease number of potential flaky tests and issues
･ Easily debug
Good Practices

33. CONFIDENTIAL designator
V0000000
Flakiness consumes resources and
time from the Product Team and
this costs money.
Conclusion
33

34. CONFIDENTIAL designator
V0000000
34
Q&A
Find me online

35. CONFIDENTIAL designator
V0000000
linkedin.com/company/red-hat
youtube.com/user/RedHatVideos
facebook.com/redhatinc
twitter.com/RedHat
35
Red Hat is the world’s leading provider of enterprise
open source software solutions. Award-winning support,
training, and consulting services make Red Hat a trusted
adviser to the Fortune 500.
Thank you
Flaky
Tests
-
How
to
deal
with
them