filter rails version and return different results in rspec

redis-memo.gemspec

@@ -26,4 +26,5 @@ Gem::Specification.new do |s|
   s.add_development_dependency 'rake'
   s.add_development_dependency 'rspec', '~> 3.2'
   s.add_development_dependency 'simplecov'
+  s.add_development_dependency 'rails'
 end

spec/memoize_query_spec.rb

@@ -449,6 +449,10 @@ def expect_to_eq_with_or_without_redis
     let!(:relation2_with_only_not) { Site.where.not(a: 2, b: 2) }
     let!(:relation3_with_only_not) { Site.where.not(a: 2).where.not(b: 1) }
     let!(:relation_with_not_and_other) { Site.where.not(a: 2).where(b: 1) }
+    # where.not(a: ..., b:...) relation is treated differently in Rails 6.0, Rails 6.1 and before Rails 6
+    # Details: https://bigbinary.com/blog/rails-6-deprecates-where-not-working-as-nor-and-will-change-to-nand-in-rails-6-1
+    let!(:special_relation_with_not) { Site.where.not(a: 2).where(b: 1) }
+
 
     it 'does not memoize queries with only NOT' do
       expect_not_to_use_redis do
@@ -464,6 +468,17 @@ def expect_to_eq_with_or_without_redis
       end
     end
 
+    it 'does not memoize but adapts to different Rails versions flexibly' do
+      if Rails.version >= '6.1'
+        # Site.where.not(a: 2).where(b: 1) will be treated as NAND in Rails 6.1
+        expect(special_relation_with_not.to_a).to eq([record])
+      else
+        # Site.where.not(a: 2).where(b: 1) will be treated as NOR in and before Rails 6.0
+        # but will give a deprecation warning in Rails 6.0
+        expect(special_relation_with_not.to_a).to eq([])
+      end
+    end
+
     it 'memoizes queries with both NOT and other bound conditions' do
       expect_to_use_redis do
         expect(relation_with_not_and_other.to_a).to eq([record])

spec/spec_helper.rb

@@ -1,5 +1,6 @@
 require 'database_cleaner/active_record'
 require 'simplecov'
+require 'rails'
 
 SimpleCov.start