adding yaml tests to verify oversampel default value

Author: Samiul-TheSoccerFan

rest-api-spec/src/yamlRestTest/resources/rest-api-spec/test/search.vectors/41_knn_search_bbq_hnsw.yml

@@ -570,7 +570,7 @@ setup:
   - match: { hits.hits.2._score: $default_rescore2 }
 
 ---
-"Test default oversample value":
+"default oversample value":
   - requires:
         cluster_features: ["mapper.dense_vector.default_oversample_value_for_bbq"]
         reason: "Needs default_oversample_value_for_bbq feature"

rest-api-spec/src/yamlRestTest/resources/rest-api-spec/test/search.vectors/42_knn_search_bbq_flat.yml

@@ -339,3 +339,14 @@ setup:
   - match: { hits.hits.0._score: $rescore_score0 }
   - match: { hits.hits.1._score: $rescore_score1 }
   - match: { hits.hits.2._score: $rescore_score2 }
+
+---
+"default oversample value":
+  - requires:
+      cluster_features: ["mapper.dense_vector.default_oversample_value_for_bbq"]
+      reason: "Needs default_oversample_value_for_bbq feature"
+  - do:
+      indices.get_mapping:
+        index: bbq_flat
+
+  - match: { bbq_flat.mappings.properties.vector.index_options.rescore_vector.oversample: 3.0 }

rest-api-spec/src/yamlRestTest/resources/rest-api-spec/test/search.vectors/42_knn_search_int4_flat.yml

@@ -495,3 +495,14 @@ setup:
   - match: { hits.hits.0._score: $rescore_score0 }
   - match: { hits.hits.1._score: $rescore_score1 }
   - match: { hits.hits.2._score: $rescore_score2 }
+
+---
+"no default oversample value":
+  - requires:
+      cluster_features: ["mapper.dense_vector.default_oversample_value_for_bbq"]
+      reason: "Needs default_oversample_value_for_bbq feature"
+  - do:
+      indices.get_mapping:
+        index: int4_flat
+
+  - not_exists: { int4_flat.mappings.properties.vector.index_options.rescore_vector }

rest-api-spec/src/yamlRestTest/resources/rest-api-spec/test/search.vectors/42_knn_search_int8_flat.yml

@@ -436,3 +436,14 @@ setup:
   - match: { hits.hits.0._score: $rescore_score0 }
   - match: { hits.hits.1._score: $rescore_score1 }
   - match: { hits.hits.2._score: $rescore_score2 }
+
+---
+"no default oversample value":
+  - requires:
+      cluster_features: ["mapper.dense_vector.default_oversample_value_for_bbq"]
+      reason: "Needs default_oversample_value_for_bbq feature"
+  - do:
+      indices.get_mapping:
+        index: int8_flat
+
+  - not_exists: { int8_flat.mappings.properties.vector.index_options.rescore_vector }