Tutorial - How to test feature flags

Strapline

Explain the idea in a sentence or two

A tutorial on how to test feature flags. Build an app, add feature flags, show how to mock PostHog in this, and write code that covers the flags.

How it will it be useful or interesting for readers/viewers

Multiple users asking about it, it’s non-obvious and probably needed by lots of people.

think of two of three possible headlines we could use

How to test with feature flags

Writing unit tests for feature flags

How to write tests for feature flagged code

Bullet point outline of structure / questions / topics to be covered

Build a python or javascript app
Write a test
Adding a feature flag
Setting up test with feature flag
Mock PostHog
- Pass mocked PostHog to provider?
- Create mocked PostHog client?
- At PostHog, we mock the /decide endpoint or mock the methods directly
- Test for when posthog.isFeatureEnabled = false
- Test for when posthog.isFeatureEnabled = true
Check for a winner in the experiment and remember to reimplement tests. They kind of provide that reminder themselves.