fix(03-01): compute correct reason in DDEvaluator instead of hardcoding TARGETING_MATCH

- Add Split parameter to resolveVariant for three-way reason computation
- Return STATIC for flags with no rules and no shards (simple flags)
- Return SPLIT for flags with no rules but with shards (shard-based flags)
- Return TARGETING_MATCH for flags with rules (rule-based flags)
- Update 9 test assertions: 7 to STATIC, 2 to SPLIT

Author: leoromanovsky

products/feature-flagging/feature-flagging-api/src/main/java/datadog/trace/api/openfeature/DDEvaluator.java

@@ -122,7 +122,7 @@ public <T> ProviderEvaluation<T> evaluate(
           for (final Split split : allocation.splits) {
             if (isEmpty(split.shards)) {
               return resolveVariant(
-                  target, key, defaultValue, flag, split.variationKey, allocation, context);
+                  target, key, defaultValue, flag, split.variationKey, allocation, split, context);
             } else {
               if (targetingKey == null) {
                 return error(defaultValue, ErrorCode.TARGETING_KEY_MISSING);
@@ -137,7 +137,7 @@ public <T> ProviderEvaluation<T> evaluate(
               }
               if (allShardsMatch) {
                 return resolveVariant(
-                    target, key, defaultValue, flag, split.variationKey, allocation, context);
+                    target, key, defaultValue, flag, split.variationKey, allocation, split, context);
               }
             }
           }
@@ -333,6 +333,7 @@ private static <T> ProviderEvaluation<T> resolveVariant(
       final Flag flag,
       final String variationKey,
       final Allocation allocation,
+      final Split split,
       final EvaluationContext context) {
     final Variant variant = flag.variations.get(variationKey);
     if (variant == null) {
@@ -377,7 +378,12 @@ private static <T> ProviderEvaluation<T> resolveVariant(
     final ProviderEvaluation<T> result =
         ProviderEvaluation.<T>builder()
             .value(mappedValue)
-            .reason(Reason.TARGETING_MATCH.name())
+            .reason(
+                !isEmpty(allocation.rules)
+                    ? Reason.TARGETING_MATCH.name()
+                    : !isEmpty(split.shards)
+                        ? Reason.SPLIT.name()
+                        : Reason.STATIC.name())
             .variant(variant.key)
             .flagMetadata(metadataBuilder.build())
             .build();

products/feature-flagging/feature-flagging-api/src/test/java/datadog/trace/api/openfeature/DDEvaluatorTest.java

@@ -5,6 +5,8 @@
 import static dev.openfeature.sdk.Reason.DEFAULT;
 import static dev.openfeature.sdk.Reason.DISABLED;
 import static dev.openfeature.sdk.Reason.ERROR;
+import static dev.openfeature.sdk.Reason.SPLIT;
+import static dev.openfeature.sdk.Reason.STATIC;
 import static dev.openfeature.sdk.Reason.TARGETING_MATCH;
 import static java.util.Arrays.asList;
 import static java.util.Collections.emptyList;
@@ -231,7 +233,7 @@ private static List<TestCase<?>> evaluateTestCases() {
         new TestCase<>("default")
             .flag("simple-string")
             .targetingKey("")
-            .result(new Result<>("test-value").reason(TARGETING_MATCH.name()).variant("on")),
+            .result(new Result<>("test-value").reason(STATIC.name()).variant("on")),
         new TestCase<>("default")
             .flag("non-existent-flag")
             .targetingKey("user-123")
@@ -243,15 +245,15 @@ private static List<TestCase<?>> evaluateTestCases() {
         new TestCase<>("default")
             .flag("simple-string")
             .targetingKey("user-123")
-            .result(new Result<>("test-value").reason(TARGETING_MATCH.name()).variant("on")),
+            .result(new Result<>("test-value").reason(STATIC.name()).variant("on")),
         new TestCase<>(false)
             .flag("boolean-flag")
             .targetingKey("user-123")
-            .result(new Result<>(true).reason(TARGETING_MATCH.name()).variant("enabled")),
+            .result(new Result<>(true).reason(STATIC.name()).variant("enabled")),
         new TestCase<>(0)
             .flag("integer-flag")
             .targetingKey("user-123")
-            .result(new Result<>(42).reason(TARGETING_MATCH.name()).variant("forty-two")),
+            .result(new Result<>(42).reason(STATIC.name()).variant("forty-two")),
         new TestCase<>("default")
             .flag("rule-based-flag")
             .targetingKey("user-premium")
@@ -261,7 +263,7 @@ private static List<TestCase<?>> evaluateTestCases() {
             .flag("rule-based-flag")
             .targetingKey("user-basic")
             .context("email", "john@gmail.com")
-            .result(new Result<>("basic").reason(TARGETING_MATCH.name()).variant("basic")),
+            .result(new Result<>("basic").reason(STATIC.name()).variant("basic")),
         new TestCase<>("default")
             .flag("numeric-rule-flag")
             .targetingKey("user-vip")
@@ -287,7 +289,7 @@ private static List<TestCase<?>> evaluateTestCases() {
             .result(
                 new Result<>("default")
                     // Result depends on shard calculation - either match or default
-                    .reason(TARGETING_MATCH.name(), DEFAULT.name())),
+                    .reason(SPLIT.name(), DEFAULT.name())),
         // Type mismatch: STRING flag evaluated as Integer
         new TestCase<>(0)
             .flag("string-number-flag")
@@ -369,7 +371,7 @@ private static List<TestCase<?>> evaluateTestCases() {
             .targetingKey("user-123")
             .result(
                 new Result<>("tracked-value")
-                    .reason(TARGETING_MATCH.name())
+                    .reason(STATIC.name())
                     .variant("tracked")
                     .flagMetadata("allocationKey", "exposure-alloc")
                     .flagMetadata("doLog", true)),
@@ -443,7 +445,7 @@ private static List<TestCase<?>> evaluateTestCases() {
             .flag("shard-matching-flag")
             .targetingKey("specific-key-that-matches-shard")
             .result(
-                new Result<>("shard-matched").reason(TARGETING_MATCH.name()).variant("matched")),
+                new Result<>("shard-matched").reason(SPLIT.name()).variant("matched")),
         new TestCase<>("default")
             .flag("future-allocation-flag")
             .targetingKey("user-123")