Improved knn support check

lib/searchkick.rb

@@ -142,6 +142,26 @@ def self.server_below?(version, true_version = false)
     Gem::Version.new(server_version.split("-")[0]) < Gem::Version.new(version.split("-")[0])
   end
 
+  # private
+  def self.knn_support?
+    if opensearch?
+      !server_below?("2.4.0", true)
+    else
+      !server_below?("8.6.0")
+    end
+  end
+
+  # private
+  def self.check_knn_support
+    unless knn_support?
+      if opensearch?
+        raise Error, "knn requires OpenSearch 2.4+"
+      else
+        raise Error, "knn requires Elasticsearch 8.6+"
+      end
+    end
+  end
+
   def self.search(term = "*", model: nil, **options, &block)
     options = options.dup
     klass = model

lib/searchkick/index_options.rb

@@ -169,8 +169,12 @@ def generate_settings
         max_shingle_diff: 4
       }
 
-      if options[:knn] && Searchkick.opensearch?
-        settings[:index][:knn] = true
+      if options[:knn]
+        Searchkick.check_knn_support
+
+        if Searchkick.opensearch?
+          settings[:index][:knn] = true
+        end
       end
 
       if options[:case_sensitive]

lib/searchkick/query.rb

@@ -529,6 +529,8 @@ def prepare
       # knn
       knn = options[:knn]
       if knn
+        Searchkick.check_knn_support
+
         if term != "*"
           raise ArgumentError, "Hybrid search not supported yet"
         end

test/knn_test.rb

@@ -2,7 +2,7 @@
 
 class KnnTest < Minitest::Test
   def setup
-    skip unless knn_support?
+    skip unless Searchkick.knn_support?
     super
   end
 

test/models/product.rb

@@ -21,7 +21,7 @@ class Product
     filterable: [:name, :color, :description],
     similarity: "BM25",
     match: ENV["MATCH"] ? ENV["MATCH"].to_sym : nil,
-    knn: knn_support? ? {embedding: {dimensions: 3}} : nil
+    knn: Searchkick.knn_support? ? {embedding: {dimensions: 3}} : nil
 
   attr_accessor :conversions, :user_ids, :aisle, :details
 

test/test_helper.rb

@@ -33,14 +33,6 @@
 
 ActiveSupport::LogSubscriber.logger = ActiveSupport::Logger.new(STDOUT) if ENV["VERBOSE"]
 
-def knn_support?
-  if Searchkick.opensearch?
-    !Searchkick.server_below?("2.4.0", true)
-  else
-    !Searchkick.server_below?("8.6.0")
-  end
-end
-
 if defined?(Mongoid)
   require_relative "support/mongoid"
 else