testland/openfeature-sdk-testing

Wraps OpenFeature (CNCF vendor-neutral SDK abstraction) testing patterns: the InMemoryProvider for hermetic tests without network calls, provider registration via OpenFeature.setProvider, the getBooleanValue/getBooleanDetails evaluation API with EvaluationDetails (value, variant, reason, errorCode), hooks for evaluation side-effects, and evaluation context for targeting-rule tests. Covers TypeScript, Java, and Python SDKs, plus per-vendor hermetic-bootstrap references for Unleash (bootstrap toggles), Flagsmith (offline LocalFileHandler), and GrowthBook (initSync payload). Use when writing tests for code that resolves feature flags through the OpenFeature SDK or the Unleash / Flagsmith / GrowthBook native SDKs; LaunchDarkly has its own skill (launchdarkly-testing).

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OpenFeature testing: Java / Python SDKs and specification tables

Companion reference for openfeature-sdk-testing. The SKILL.md spine shows the full TypeScript/Node.js flow; the flow is identical here, only the API names differ.

Java

Install (Maven, per github.com/open-feature/java-sdk README):

<dependency>
  <groupId>dev.openfeature</groupId>
  <artifactId>sdk</artifactId>
  <version>1.20.2</version>
</dependency>

Configure the InMemoryProvider:

import dev.openfeature.sdk.OpenFeatureAPI;
import dev.openfeature.sdk.Client;
import dev.openfeature.sdk.providers.memory.Flag;
import dev.openfeature.sdk.providers.memory.InMemoryProvider;

Map<String, Flag<?>> flags = new HashMap<>();
flags.put("show-new-ui", Flag.builder()
    .variant("on", true)
    .variant("off", false)
    .defaultVariant("on")
    .build());

OpenFeatureAPI api = OpenFeatureAPI.getInstance();
api.setProviderAndWait(new InMemoryProvider(flags));
Client client = api.getClient();

Evaluate flags:

boolean enabled = client.getBooleanValue("show-new-ui", false);

FlagEvaluationDetails<Boolean> details =
    client.getBooleanDetails("show-new-ui", false);
// details.getValue()    - resolved value
// details.getVariant()  - "on" or "off"
// details.getReason()   - "STATIC", "DEFAULT", etc.
// details.getErrorCode()- ErrorCode.FLAG_NOT_FOUND, TYPE_MISMATCH, etc.

Per-invocation evaluation context:

Map<String, Value> attrs = new HashMap<>();
attrs.put("email", new Value("user@example.com"));
EvaluationContext ctx = new ImmutableContext("user-42", attrs);
boolean value = client.getBooleanValue("beta-access", false, ctx);

Python

Install (per github.com/open-feature/python-sdk README):

pip install openfeature-sdk==0.10.0

Configure the InMemoryProvider:

from openfeature import api
from openfeature.provider.in_memory_provider import InMemoryFlag, InMemoryProvider

flags = {
    "show-new-ui": InMemoryFlag(
        default_variant="on",
        variants={"on": True, "off": False}
    ),
}

api.set_provider_and_wait(InMemoryProvider(flags))
client = api.get_client()

Evaluate flags:

enabled = client.get_boolean_value("show-new-ui", False)

details = client.get_boolean_details("show-new-ui", False)
# details.value       - resolved value
# details.variant     - "on" / "off"
# details.reason      - "STATIC", "DEFAULT", etc.
# details.error_code  - "FLAG_NOT_FOUND", "TYPE_MISMATCH", etc.

Per-invocation evaluation context:

from openfeature.evaluation_context import EvaluationContext
ctx = EvaluationContext(targeting_key="user-42",
                        attributes={"email": "user@example.com"})
details = client.get_boolean_details("beta-access", False, ctx)

EvaluationDetails and reason codes

Per the OpenFeature specification (openfeature.dev/specification/sections/flag-evaluation, Requirements 1.4.3-1.4.15), EvaluationDetails carries:

Field	Type	Meaning
`value`	T	Resolved flag value (spec req. 1.4.3)
`flagKey`	string	The requested flag identifier (1.4.5)
`variant`	string	Provider-supplied variant name (1.4.6)
`reason`	string	Resolution rationale (1.4.7)
`errorCode`	enum	Failure classification (1.4.8)
`errorMessage`	string	Optional context for the error (1.4.13)
`flagMetadata`	map	Immutable provider-supplied data (1.4.14)

Canonical reason values (per openfeature.dev/specification/sections/providers, Requirement 2.2.5): STATIC, DEFAULT, TARGETING_MATCH, SPLIT, CACHED, DISABLED, UNKNOWN, STALE, ERROR.

Canonical error codes include FLAG_NOT_FOUND, TYPE_MISMATCH, PARSE_ERROR, TARGETING_KEY_MISSING, INVALID_CONTEXT, GENERAL, PROVIDER_NOT_READY, PROVIDER_FATAL.

Hook lifecycle stages and execution order

Per openfeature.dev/docs/reference/concepts/hooks and the specification (openfeature.dev/specification/sections/hooks, Requirement 4.3.1-4.3.8), the four stages are:

Stage	Runs when
`before`	Before flag resolution; can modify evaluation context
`after`	After successful resolution; can validate the returned value
`error`	On resolution failure or unhandled before-hook error
`finally`	Unconditionally after all other stages

Execution order for before: API - Client - Invocation. For after, error, finally: reverse order (Invocation - Client - API), per specification Requirement 4.4.2.