fix: Correct logic for evaluation blocked for ERROR and STALE providers

[NeaguGeorgiana23]

This PR

Fixes the flag evaluation which was incorrectly blocked when the feature provider was in ERROR or STALE states.

Previously, the SDK short-circuited evaluation for any provider status other than READY. This PR updates the EvaluateFlag logic to strictly follow the OpenFeature specification by:

• Short-circuiting and returning the PROVIDER_NOT_READY error code only when the provider is NOT_READY (Requirement 1.7.6).
• Short-circuiting and returning the PROVIDER_FATAL error code only when the provider is in a FATAL error state (Requirement 1.7.7).
• Allowing evaluation to proceed for READY, ERROR, and STALE states, ensuring cached values can still be returned when appropriate.

Related Issues

Fixes #69

Notes

• Implements compliance for OpenFeature specification Requirements 1.7.6 and 1.7.7.
• Remaining minor bugs from the tracking issue will be addressed in subsequent PRs.

Follow-up Tasks

• Address remaining minor bugs in the compliance tracking issue

[gemini-code-assist]

Code Review

This pull request updates the EvaluateFlag method in ClientAPI to explicitly handle different provider statuses. It replaces the generic non-ready check with specific logic for ProviderStatus::kNotReady and ProviderStatus::kFatal, ensuring that a fatal provider state returns the appropriate ErrorCode::kProviderFatal. I have no feedback to provide as there were no review comments to evaluate.

[toddbaert]

Could possibly benefit from test coverage but I'll let you decide if the tradeoff is worth it.

[coderabbitai]

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📥 Commits

Reviewing files that changed from the base of the PR and between 9a98411 and a43a6e7.

📒 Files selected for processing (1)

• test/client_api_test.cpp

🚧 Files skipped from review as they are similar to previous changes (1)

• test/client_api_test.cpp

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📝 Walkthrough

Walkthrough

ClientAPI::EvaluateFlag replaces a single != kReady check with two explicit branches: kNotReady returns kProviderNotReady with "Provider is not ready", and kFatal returns kProviderFatal with a distinct error message. New test cases validate that evaluations are blocked for kNotReady and kFatal states, and proceed for kError and kStale states with cached results.

Changes

Provider Fatal Error Code Fix

Layer / File(s)	Summary
EvaluateFlag provider status branching openfeature/client_api.h	Splits the former single != kReady branch into kNotReady → kProviderNotReady and kFatal → kProviderFatal, each with its own error message.
Test coverage for provider status handling test/client_api_test.cpp	Adds ErrorCode imports and new ClientAPITest cases validating that evaluations block for kNotReady/kFatal states and proceed for kError/kStale states with cached results.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related PRs

• open-feature/cpp-sdk#97: Also modifies ClientAPI::EvaluateFlag error-handling paths in the same file, refactoring evaluation failure and exception handling via StatusOr.

Suggested reviewers

• oxddr
• toddbaert

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 12.50% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately summarizes the main change: fixing evaluation logic for ERROR and STALE providers, which is the primary objective of this PR.
Description check	✅ Passed	The description clearly explains what was fixed, why it matters, and references the linked specification requirements.
Linked Issues check	✅ Passed	The PR implements the required fixes from issue #69: distinguishing PROVIDER_NOT_READY from PROVIDER_FATAL errors and allowing evaluation for ERROR/STALE providers.
Out of Scope Changes check	✅ Passed	All changes are directly related to fixing the evaluation logic for provider states as specified in the linked issue #69.

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