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Choose QA tests

Describes the different QA options and gives best practices for QA in Optimizely Feature Experimentation.

Best practices for what to test

The traditional method for automating QA tests will not scale with a large number of feature flags. If you try to unit test, integrate test, and end-to-end test every combination of every flag and its variations, you will get an explosion of tests.

At a high level, here is some guidance for automating tests selectively:

  • Unit tests – Should be agnostic of feature flags. If a unit test has to be aware of flags, then mock and stub flags.
  • Integration tests – Should also have as little awareness of feature flags as possible. Focus on individual code paths to ensure proper business logic and integration. Force the particular flag variations you want to test by using mocks and stubs For example, you can mock a Decide SDK call to always return true in an integration test.
  • Manual verification – Is expensive, so reserve a human QA tester for business-critical variations and flags.
  • End-to-End tests – Are the most expensive to write and maintain, so reserve these only for the most business-critical experimental or flag paths. Include a test that checks what happens if all feature flags are enabled. Include another test to check that the system can degrade gracefully in the unlikely event your flag system goes down.

Which QA tool to choose

For a sense of how we at Optimizely Feature Experimentation uses these tools, see the blog on Automation Testing Feature Flags.

AllowlistAudience attribute = "QA"Forced Variation
GranularityFlag variables
Flag variations
ExperimentsFlag variations
Example Use CasesMocks during development

Allowlist a test runner so you always see the variation you want the test to assert against.
Mocks during development

Automated web UI test

Manual web UI test
Tests run on a behavior-driven development (BDD) framework
Ease of useEasiest. It can override all other configurations, allowing you to leave your intended flag rule configuration intact while you QA.Medium (requires some flag rule configuration changes)Harder
Available forA/B experimentsA/B tests
A/B experiments
CommentsCan use with only 10 user IDs per experiment (it would skew experimental results if more were allowed)Two easy implementations are to audience match on:

1. a URL query parameter
2. a cookie

Keep your experiment data clean

The preceding QA tools are for flag rules that are already running or enabled. But how do you keep from exposing end users to your in-development, running experiment? You can:

On the flip side, when you are done with QA and ready for your experiment to go live with real data, you want to discard the events your QA testers triggered. You do not want their testing showing up on your results page. Optimizely Feature Experimentation does not yet support discarding data automatically when you switch your experiment from running in a non-production environment to a product environment. Instead, you can easily get rid of the QA events if you "Reset Results."