First CSV tests

Author: carlosdelest

x-pack/plugin/esql/qa/testFixtures/src/main/resources/vector-cosine-similarity.csv-spec

@@ -0,0 +1,61 @@
+ # Tests for cosine similarity function
+ 
+ similarityWithVectorField
+ required_capability: cosine_vector_similarity_function
+ 
+ from colors
+ | where color != "black" 
+ | eval similarity = round(v_cosine(rgb_vector, [0, 255, 255]), 3) 
+ | sort similarity desc, color asc 
+ | limit 10
+ | keep color, similarity
+ ;
+ 
+color:text     | similarity:double
+cyan           | 1.0            
+teal           | 1.0            
+turquoise      | 0.989          
+aqua marine    | 0.965          
+azure          | 0.916          
+lavender       | 0.914          
+honeydew       | 0.912          
+mint cream     | 0.912          
+gainsboro      | 0.908          
+gray           | 0.908     
+;
+
+# TODO Need to implement a conversion function to convert a non-foldable row to a dense_vector
+similarityWithRow-Ignore
+required_capability: cosine_vector_similarity_function
+ 
+row vector = [1, 2, 3] 
+| eval similarity = round(v_cosine(vector, [0, 1, 2]), 3) 
+| sort similarity desc, color asc 
+| limit 10
+| keep color, similarity
+;
+
+color:text     | similarity:double
+cyan           | 1.0            
+teal           | 1.0            
+turquoise      | 0.989          
+aqua marine    | 0.965          
+azure          | 0.916          
+lavender       | 0.914          
+honeydew       | 0.912          
+mint cream     | 0.912          
+gainsboro      | 0.908          
+gray           | 0.908     
+;
+
+similarityWithLiteralVectors
+required_capability: cosine_vector_similarity_function
+ 
+row a = 1
+| eval similarity = round(v_cosine([1, 2, 3], [0, 1, 2]), 3) 
+| keep similarity
+;
+
+similarity:double
+0.978  
+;

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/expression/function/vector/VectorWritables.java

@@ -21,13 +21,14 @@ public final class VectorWritables {
 
     private VectorWritables() {
         // Utility class
+        throw new UnsupportedOperationException();
     }
 
     public static List<NamedWriteableRegistry.Entry> getNamedWritables() {
         List<NamedWriteableRegistry.Entry> entries = new ArrayList<>();
 
         if (EsqlCapabilities.Cap.KNN_FUNCTION_V2.isEnabled()) {
-            return List.of(Knn.ENTRY);
+            entries.add(Knn.ENTRY);
         }
         if (EsqlCapabilities.Cap.COSINE_VECTOR_SIMILARITY_FUNCTION.isEnabled()) {
             entries.add(CosineSimilarity.ENTRY);