fix: Simplify variant assignment in EvaluationEventBuilder and enhance tests for missing flag metadata

Signed-off-by: André Silva <2493377+askpt@users.noreply.github.com>

Author: askpt

src/OpenFeature/Telemetry/EvaluationEventBuilder.cs

@@ -29,11 +29,7 @@ public static EvaluationEvent Build(HookContext<Value> hookContext, FlagEvaluati
 
         var body = new Dictionary<string, object>();
 
-        if (!string.IsNullOrWhiteSpace(details.Variant))
-        {
-            attributes[TelemetryConstants.Variant] = details.Variant ?? details.Value.ToString();
-        }
-
+        attributes[TelemetryConstants.Variant] = details.Variant;
         attributes[TelemetryFlagMetadata.ContextId] = details.FlagMetadata?.GetString(TelemetryFlagMetadata.ContextId);
         attributes[TelemetryFlagMetadata.FlagSetId] = details.FlagMetadata?.GetString(TelemetryFlagMetadata.FlagSetId);
         attributes[TelemetryFlagMetadata.Version] = details.FlagMetadata?.GetString(TelemetryFlagMetadata.Version);

test/OpenFeature.Tests/Telemetry/EvaluationEventBuilderTests.cs

@@ -75,14 +75,35 @@ public void Build_ShouldHandleMissingVariant()
                 { "flagSetId", "flagSetId" }, { "contextId", "contextId" }, { "version", "version" }
             };
             var flagMetadata = new ImmutableMetadata(metadata);
+            var details = new FlagEvaluationDetails<Value>("flagKey", new Value("value"), ErrorType.None,
+                reason: "reason", variant: null, flagMetadata: flagMetadata);
+
+            // Act
+            var evaluationEvent = EvaluationEventBuilder.Build(hookContext, details);
+
+            // Assert
+            Assert.Null(evaluationEvent.Attributes[TelemetryConstants.Variant]);
+        }
+
+        [Fact]
+        public void Build_ShouldHandleMissingFlagMetadata()
+        {
+            // Arrange
+            var clientMetadata = new ClientMetadata("client", "1.0.0");
+            var providerMetadata = new Metadata("provider");
+            var hookContext = new HookContext<Value>("flagKey", new Value("value"), FlagValueType.Object, clientMetadata,
+                providerMetadata, EvaluationContext.Empty);
+            var flagMetadata = new ImmutableMetadata();
             var details = new FlagEvaluationDetails<Value>("flagKey", new Value("value"), ErrorType.None,
                 reason: "reason", variant: "", flagMetadata: flagMetadata);
 
             // Act
             var evaluationEvent = EvaluationEventBuilder.Build(hookContext, details);
 
             // Assert
-            Assert.Throws<KeyNotFoundException>(() => evaluationEvent.Attributes[TelemetryConstants.Variant]);
+            Assert.Null(evaluationEvent.Attributes[TelemetryFlagMetadata.ContextId]);
+            Assert.Null(evaluationEvent.Attributes[TelemetryFlagMetadata.FlagSetId]);
+            Assert.Null(evaluationEvent.Attributes[TelemetryFlagMetadata.Version]);
         }
     }
 }