7 files changed, 74 insertions, 9 deletions
diff --git a/activerecord/test/cases/relation/delegation_test.rb b/activerecord/test/cases/relation/delegation_test.rb
index 2696d1bb00..3f3d41980c 100644
--- a/activerecord/test/cases/relation/delegation_test.rb
+++ b/activerecord/test/cases/relation/delegation_test.rb
@@ -54,4 +54,32 @@ module ActiveRecord
       Comment.all
     end
   end
+
+  class QueryingMethodsDelegationTest < ActiveRecord::TestCase
+    QUERYING_METHODS = [
+      :find, :take, :take!, :first, :first!, :last, :last!, :exists?, :any?, :many?, :none?, :one?,
+      :second, :second!, :third, :third!, :fourth, :fourth!, :fifth, :fifth!, :forty_two, :forty_two!, :third_to_last, :third_to_last!, :second_to_last, :second_to_last!,
+      :first_or_create, :first_or_create!, :first_or_initialize,
+      :find_or_create_by, :find_or_create_by!, :create_or_find_by, :create_or_find_by!, :find_or_initialize_by,
+      :find_by, :find_by!,
+      :destroy_all, :delete_all, :update_all,
+      :find_each, :find_in_batches, :in_batches,
+      :select, :group, :order, :except, :reorder, :limit, :offset, :joins, :left_joins, :left_outer_joins, :or,
+      :where, :rewhere, :preload, :eager_load, :includes, :from, :lock, :readonly, :extending,
+      :having, :create_with, :distinct, :references, :none, :unscope, :merge,
+      :count, :average, :minimum, :maximum, :sum, :calculate,
+      :pluck, :pick, :ids,
+    ]
+
+    def test_delegate_querying_methods
+      klass = Class.new(ActiveRecord::Base) do
+        self.table_name = "posts"
+      end
+
+      QUERYING_METHODS.each do |method|
+        assert_respond_to klass.all, method
+        assert_respond_to klass, method
+      end
+    end
+  end
 end
diff --git a/activerecord/test/cases/relation/merging_test.rb b/activerecord/test/cases/relation/merging_test.rb
index b68b3723f6..f53ef1fe35 100644
--- a/activerecord/test/cases/relation/merging_test.rb
+++ b/activerecord/test/cases/relation/merging_test.rb
@@ -58,7 +58,7 @@ class RelationMergingTest < ActiveRecord::TestCase
 
   def test_relation_merging_with_locks
     devs = Developer.lock.where("salary >= 80000").order("id DESC").merge(Developer.limit(2))
-    assert devs.locked?
+    assert_predicate devs, :locked?
   end
 
   def test_relation_merging_with_preload
@@ -72,6 +72,16 @@ class RelationMergingTest < ActiveRecord::TestCase
     assert_equal 1, comments.count
   end
 
+  def test_relation_merging_with_left_outer_joins
+    comments = Comment.joins(:post).where(body: "Thank you for the welcome").merge(Post.left_outer_joins(:author).where(body: "Such a lovely day"))
+
+    assert_equal 1, comments.count
+  end
+
+  def test_relation_merging_with_skip_query_cache
+    assert_equal Post.all.merge(Post.all.skip_query_cache!).skip_query_cache_value, true
+  end
+
   def test_relation_merging_with_association
     assert_queries(2) do  # one for loading post, and another one merged query
       post = Post.where(body: "Such a lovely day").first
@@ -107,9 +117,9 @@ class RelationMergingTest < ActiveRecord::TestCase
 
   def test_merging_with_from_clause
     relation = Post.all
-    assert relation.from_clause.empty?
+    assert_empty relation.from_clause
     relation = relation.merge(Post.from("posts"))
-    refute relation.from_clause.empty?
+    assert_not_empty relation.from_clause
   end
 end
 
diff --git a/activerecord/test/cases/relation/mutation_test.rb b/activerecord/test/cases/relation/mutation_test.rb
index ad3700b73a..f82ecd4449 100644
--- a/activerecord/test/cases/relation/mutation_test.rb
+++ b/activerecord/test/cases/relation/mutation_test.rb
@@ -25,7 +25,7 @@ module ActiveRecord
     test "#order! with symbol prepends the table name" do
       assert relation.order!(:name).equal?(relation)
       node = relation.order_values.first
-      assert node.ascending?
+      assert_predicate node, :ascending?
       assert_equal :name, node.expr.name
       assert_equal "posts", node.expr.relation.name
     end
@@ -88,7 +88,7 @@ module ActiveRecord
       assert relation.reorder!(:name).equal?(relation)
       node = relation.order_values.first
 
-      assert node.ascending?
+      assert_predicate node, :ascending?
       assert_equal :name, node.expr.name
       assert_equal "posts", node.expr.relation.name
     end
@@ -137,9 +137,14 @@ module ActiveRecord
       assert relation.skip_query_cache_value
     end
 
+    test "skip_preloading!" do
+      relation.skip_preloading!
+      assert relation.skip_preloading_value
+    end
+
     private
       def relation
-        @relation ||= Relation.new(FakeKlass, Post.arel_table, Post.predicate_builder)
+        @relation ||= Relation.new(FakeKlass)
       end
   end
 end
diff --git a/activerecord/test/cases/relation/or_test.rb b/activerecord/test/cases/relation/or_test.rb
index 7e418f9c7d..065819e0f1 100644
--- a/activerecord/test/cases/relation/or_test.rb
+++ b/activerecord/test/cases/relation/or_test.rb
@@ -126,5 +126,12 @@ module ActiveRecord
       expected = Author.find(1).posts + Post.where(title: "I don't have any comments")
       assert_equal expected.sort_by(&:id), actual.sort_by(&:id)
     end
+
+    def test_or_with_scope_on_association
+      author = Author.first
+      assert_nothing_raised do
+        author.top_posts.or(author.other_top_posts)
+      end
+    end
   end
 end
diff --git a/activerecord/test/cases/relation/select_test.rb b/activerecord/test/cases/relation/select_test.rb
new file mode 100644
index 0000000000..0577e6bfdb
--- /dev/null
+++ b/activerecord/test/cases/relation/select_test.rb
@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+require "cases/helper"
+require "models/post"
+
+module ActiveRecord
+  class SelectTest < ActiveRecord::TestCase
+    fixtures :posts
+
+    def test_select_with_nil_agrument
+      expected = Post.select(:title).to_sql
+      assert_equal expected, Post.select(nil).select(:title).to_sql
+    end
+  end
+end
diff --git a/activerecord/test/cases/relation/where_clause_test.rb b/activerecord/test/cases/relation/where_clause_test.rb
index e5eb159d36..8703d238a0 100644
--- a/activerecord/test/cases/relation/where_clause_test.rb
+++ b/activerecord/test/cases/relation/where_clause_test.rb
@@ -75,8 +75,8 @@ class ActiveRecord::Relation
     end
 
     test "a clause knows if it is empty" do
-      assert WhereClause.empty.empty?
-      assert_not WhereClause.new(["anything"]).empty?
+      assert_empty WhereClause.empty
+      assert_not_empty WhereClause.new(["anything"])
     end
 
     test "invert cannot handle nil" do
diff --git a/activerecord/test/cases/relation/where_test.rb b/activerecord/test/cases/relation/where_test.rb
index d95a54a2fe..99797528b2 100644
--- a/activerecord/test/cases/relation/where_test.rb
+++ b/activerecord/test/cases/relation/where_test.rb
@@ -265,7 +265,7 @@ module ActiveRecord
     end
 
     def test_where_with_decimal_for_string_column
-      count = Post.where(title: BigDecimal.new(0)).count
+      count = Post.where(title: BigDecimal(0)).count
       assert_equal 0, count
     end