HttpContextFeatureFlagCache.GetCacheKey prevents evaluation of multiple distinct feature keys and property values

[0xfeeddeadbeef]

Steps to reproduce

1. Create a new feature flag with name test_feat_1 and condition test_prop equals "A"
2. Create a new feature flag with name test_feat_2 and condition test_prop equals "A"
3. Clone the repo: https://github.com/0xfeeddeadbeef/PostHogRepro.git
4. Open the project and set your project API key on line 17 of Program.cs
5. Run the project

Expected output

Feature: test_feat_1, User: test_user, Property: test_prop, IsEnabled: True
Feature: test_feat_1, User: test_user, Property: test_prop, IsEnabled: False
Feature: test_feat_2, User: test_user, Property: test_prop, IsEnabled: False
Feature: test_feat_2, User: test_user, Property: test_prop, IsEnabled: False

Actual output

Feature: test_feat_1, User: test_user, Property: test_prop, IsEnabled: True
Feature: test_feat_1, User: test_user, Property: test_prop, IsEnabled: True
Feature: test_feat_2, User: test_user, Property: test_prop, IsEnabled: True
Feature: test_feat_2, User: test_user, Property: test_prop, IsEnabled: True

Root cause

Looks like the HttpContextFeatureFlagCache.GetCacheKey method assumes that only one feature key (and with exactly the same property values) will ever be evaluated during a single ASP.NET Core HTTP request processing.

Workaround

Enable local evaluation.