feat: add segment source metadata enum and bump-engine-test-data (#24)

- Add SegmentSource enum with Api and IdentityOverride variants
- Update SegmentMetadata to use typed SegmentSource instead of optional string
- Add snake_case serialization to support test data format
- Update engine-test-data submodule to v3.4.2
- Export SegmentSource in public API

Author: gagantrivedi

.gitmodules

@@ -1,4 +1,4 @@
 [submodule "tests/engine_tests/engine-test-data"]
 	path = tests/engine_tests/engine-test-data
 	url = https://github.com/flagsmith/engine-test-data.git
-	branch = v1.0.0
+	branch = v3.4.2

src/engine_eval/context.rs

@@ -2,6 +2,15 @@ use crate::types::FlagsmithValue;
 use serde::{Deserialize, Serialize};
 use std::collections::HashMap;
 
+#[derive(Clone, Debug, Serialize, Deserialize, PartialEq)]
+#[serde(rename_all = "snake_case")]
+pub enum SegmentSource {
+    /// Segment came from the Flagsmith API.
+    Api,
+    /// Segment was created from identity overrides.
+    IdentityOverride,
+}
+
 /// Represents metadata information about a feature.
 #[derive(Clone, Debug, Serialize, Deserialize, Default, PartialEq)]
 pub struct FeatureMetadata {
@@ -195,14 +204,22 @@ pub struct SegmentRule {
 }
 
 /// Segment metadata.
-#[derive(Clone, Debug, Serialize, Deserialize, Default, PartialEq)]
+#[derive(Clone, Debug, Serialize, Deserialize, PartialEq)]
 pub struct SegmentMetadata {
     /// Segment ID.
     #[serde(skip_serializing_if = "Option::is_none")]
     pub segment_id: Option<i32>,
-    /// Source of the segment (api or identity_override).
-    #[serde(skip_serializing_if = "Option::is_none")]
-    pub source: Option<String>,
+    /// Source of the segment.
+    pub source: SegmentSource,
+}
+
+impl Default for SegmentMetadata {
+    fn default() -> Self {
+        Self {
+            segment_id: None,
+            source: SegmentSource::Api,
+        }
+    }
 }
 
 /// Represents a segment context for feature flag evaluation.

src/engine_eval/mappers.rs

@@ -1,7 +1,7 @@
 use super::context::{
     Condition, ConditionOperator, EngineEvaluationContext, EnvironmentContext, FeatureContext,
     FeatureMetadata, FeatureValue, IdentityContext, SegmentContext, SegmentMetadata, SegmentRule,
-    SegmentRuleType,
+    SegmentRuleType, SegmentSource,
 };
 use crate::environments::Environment;
 use crate::features::{FeatureState, MultivariateFeatureStateValue};
@@ -100,7 +100,7 @@ fn map_segment_to_segment_context(segment: &Segment) -> SegmentContext {
         name: segment.name.clone(),
         metadata: SegmentMetadata {
             segment_id: Some(segment.id as i32),
-            source: Some("api".to_string()),
+            source: SegmentSource::Api,
         },
         overrides: vec![],
         rules: vec![],
@@ -237,7 +237,7 @@ fn map_identity_overrides_to_segments(identities: &[Identity]) -> HashMap<String
             name: "identity_overrides".to_string(),
             metadata: SegmentMetadata {
                 segment_id: None,
-                source: Some("identity_override".to_string()),
+                source: SegmentSource::IdentityOverride,
             },
             overrides: vec![],
             rules: vec![SegmentRule {

src/engine_eval/mod.rs

@@ -11,7 +11,7 @@ pub mod segment_evaluator;
 pub mod mappers;
 
 // Re-export commonly used types for convenience
-pub use context::{EngineEvaluationContext, FeatureContext, FeatureMetadata};
+pub use context::{EngineEvaluationContext, FeatureContext, FeatureMetadata, SegmentSource};
 pub use mappers::{add_identity_to_context, environment_to_context};
 pub use result::{EvaluationResult, FlagResult, SegmentResult};
 pub use segment_evaluator::is_context_in_segment;