8 files changed, 11 insertions, 12 deletions
diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb b/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
index 16260fe565..3516bef75a 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
@@ -22,8 +22,8 @@ module ActiveRecord
         def create_database(name, options = {})
           options = { encoding: "utf8" }.merge!(options.symbolize_keys)
 
-          option_string = options.inject("") do |memo, (key, value)|
-            memo += case key
+          option_string = options.each_with_object(+"") do |(key, value), memo|
+            memo << case key
                     when :owner
                       " OWNER = \"#{value}\""
                     when :template
diff --git a/activerecord/lib/active_record/timestamp.rb b/activerecord/lib/active_record/timestamp.rb
index d32f971ad1..e19077eb88 100644
--- a/activerecord/lib/active_record/timestamp.rb
+++ b/activerecord/lib/active_record/timestamp.rb
@@ -56,7 +56,7 @@ module ActiveRecord
       def touch_attributes_with_time(*names, time: nil)
         attribute_names = timestamp_attributes_for_update_in_model
         attribute_names |= names.map(&:to_s)
-        attribute_names.index_with(time ||= current_time_from_proper_timezone)
+        attribute_names.index_with(time || current_time_from_proper_timezone)
       end
 
       private
diff --git a/activerecord/lib/arel/visitors/informix.rb b/activerecord/lib/arel/visitors/informix.rb
index 0a9713794e..208fa15aef 100644
--- a/activerecord/lib/arel/visitors/informix.rb
+++ b/activerecord/lib/arel/visitors/informix.rb
@@ -15,8 +15,9 @@ module Arel # :nodoc: all
             collector << "ORDER BY "
             collector = inject_join o.orders, collector, ", "
           end
-          collector = maybe_visit o.lock, collector
+          maybe_visit o.lock, collector
         end
+
         def visit_Arel_Nodes_SelectCore(o, collector)
           collector = inject_join o.projections, collector, ", "
           if o.source && !o.source.empty?
diff --git a/activerecord/lib/arel/visitors/oracle12.rb b/activerecord/lib/arel/visitors/oracle12.rb
index b092aa95e0..9a7fe4d626 100644
--- a/activerecord/lib/arel/visitors/oracle12.rb
+++ b/activerecord/lib/arel/visitors/oracle12.rb
@@ -20,7 +20,7 @@ module Arel # :nodoc: all
         def visit_Arel_Nodes_SelectOptions(o, collector)
           collector = maybe_visit o.offset, collector
           collector = maybe_visit o.limit, collector
-          collector = maybe_visit o.lock, collector
+          maybe_visit o.lock, collector
         end
 
         def visit_Arel_Nodes_Limit(o, collector)
diff --git a/activerecord/lib/arel/visitors/to_sql.rb b/activerecord/lib/arel/visitors/to_sql.rb
index f9fe4404eb..b5a960ce68 100644
--- a/activerecord/lib/arel/visitors/to_sql.rb
+++ b/activerecord/lib/arel/visitors/to_sql.rb
@@ -208,14 +208,12 @@ module Arel # :nodoc: all
           end
 
           visit_Arel_Nodes_SelectOptions(o, collector)
-
-          collector
         end
 
         def visit_Arel_Nodes_SelectOptions(o, collector)
           collector = maybe_visit o.limit, collector
           collector = maybe_visit o.offset, collector
-          collector = maybe_visit o.lock, collector
+          maybe_visit o.lock, collector
         end
 
         def visit_Arel_Nodes_SelectCore(o, collector)
diff --git a/activerecord/test/cases/batches_test.rb b/activerecord/test/cases/batches_test.rb
index d21218a997..cf6e280898 100644
--- a/activerecord/test/cases/batches_test.rb
+++ b/activerecord/test/cases/batches_test.rb
@@ -430,7 +430,7 @@ class EachTest < ActiveRecord::TestCase
         assert_kind_of ActiveRecord::Relation, relation
         assert_kind_of Post, relation.first
 
-        relation = [not_a_post] * relation.count
+        [not_a_post] * relation.count
       end
     end
   end
diff --git a/activerecord/test/cases/counter_cache_test.rb b/activerecord/test/cases/counter_cache_test.rb
index 99d286dc52..cc4f86a0fb 100644
--- a/activerecord/test/cases/counter_cache_test.rb
+++ b/activerecord/test/cases/counter_cache_test.rb
@@ -144,7 +144,7 @@ class CounterCacheTest < ActiveRecord::TestCase
 
   test "update other counters on parent destroy" do
     david, joanna = dog_lovers(:david, :joanna)
-    joanna = joanna # squelch a warning
+    _ = joanna # squelch a warning
 
     assert_difference "joanna.reload.dogs_count", -1 do
       david.destroy
diff --git a/activerecord/test/cases/inheritance_test.rb b/activerecord/test/cases/inheritance_test.rb
index 3d3189900f..19655a2d38 100644
--- a/activerecord/test/cases/inheritance_test.rb
+++ b/activerecord/test/cases/inheritance_test.rb
@@ -240,7 +240,7 @@ class InheritanceTest < ActiveRecord::TestCase
     cabbage = vegetable.becomes!(Cabbage)
     assert_equal "Cabbage", cabbage.custom_type
 
-    vegetable = cabbage.becomes!(Vegetable)
+    cabbage.becomes!(Vegetable)
     assert_nil cabbage.custom_type
   end
 
@@ -654,7 +654,7 @@ class InheritanceAttributeMappingTest < ActiveRecord::TestCase
 
     assert_equal ["omg_inheritance_attribute_mapping_test/company"], ActiveRecord::Base.connection.select_values("SELECT sponsorable_type FROM sponsors")
 
-    sponsor = Sponsor.first
+    sponsor = Sponsor.find(sponsor.id)
     assert_equal startup, sponsor.sponsorable
   end
 end