Added factor to conversions_v2 option - resolves #1691

Author: ankane

lib/searchkick/query.rb

@@ -685,7 +685,8 @@ def set_conversions_v2
         {
           rank_feature: {
             field: "#{conversions_field}.#{conversions_term.to_s.downcase.gsub(".", "*")}",
-            linear: {}
+            linear: {},
+            boost: conversions_v2[:factor] || 1
           }
         }
       end

test/conversions_test.rb

@@ -127,6 +127,20 @@ def test_v2_score
     assert_equal scores, scores_v2
   end
 
+  def test_v2_factor
+    store [
+      {name: "Tomato A", conversions: {"tomato" => 1}, conversions_v2: {"tomato" => 1}},
+      {name: "Tomato B", conversions: {"tomato" => 2}, conversions_v2: {"tomato" => 2}},
+      {name: "Tomato C", conversions: {"tomato" => 3}, conversions_v2: {"tomato" => 3}}
+    ]
+    scores = Product.search("tomato", conversions_v1: false, conversions_v2: true, load: false).map(&:_score)
+    scores2 = Product.search("tomato", conversions_v1: false, conversions_v2: {factor: 3}, load: false).map(&:_score)
+    diffs = scores.zip(scores2).map { |a, b| b - a }
+    assert_in_delta 6, diffs[0]
+    assert_in_delta 4, diffs[1]
+    assert_in_delta 2, diffs[2]
+  end
+
   def test_v2_no_tokenization
     store [
       {name: "Tomato A"},