5 files changed, 34 insertions, 5 deletions
diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md
index fa2b7f0c0f..b6a943eca7 100644
--- a/activerecord/CHANGELOG.md
+++ b/activerecord/CHANGELOG.md
@@ -1,3 +1,12 @@
+*   Make `unscope` aware of "less than" and "greater than" conditions.
+
+    *TAKAHASHI Kazuaki*
+
+*   `find_by` and `find_by!` raise `ArgumentError` when called without
+    arguments.
+
+    *Kohei Suzuki*
+
 *   Revert behavior of `db:schema:load` back to loading the full
     environment. This ensures that initializers are run.
 
diff --git a/activerecord/lib/active_record/relation/finder_methods.rb b/activerecord/lib/active_record/relation/finder_methods.rb
index 6a3a56f1cc..576a32bf75 100644
--- a/activerecord/lib/active_record/relation/finder_methods.rb
+++ b/activerecord/lib/active_record/relation/finder_methods.rb
@@ -77,16 +77,16 @@ module ActiveRecord
     #
     #   Post.find_by name: 'Spartacus', rating: 4
     #   Post.find_by "published_at < ?", 2.weeks.ago
-    def find_by(*args)
-      where(*args).take
+    def find_by(arg, *args)
+      where(arg, *args).take
     rescue RangeError
       nil
     end
 
     # Like <tt>find_by</tt>, except that if no record is found, raises
     # an <tt>ActiveRecord::RecordNotFound</tt> error.
-    def find_by!(*args)
-      where(*args).take!
+    def find_by!(arg, *args)
+      where(arg, *args).take!
     rescue RangeError
       raise RecordNotFound, "Couldn't find #{@klass.name} with an out of range value"
     end
diff --git a/activerecord/lib/active_record/relation/where_clause.rb b/activerecord/lib/active_record/relation/where_clause.rb
index f9b9e640ec..1f000b3f0f 100644
--- a/activerecord/lib/active_record/relation/where_clause.rb
+++ b/activerecord/lib/active_record/relation/where_clause.rb
@@ -135,7 +135,7 @@ module ActiveRecord
       def predicates_except(columns)
         predicates.reject do |node|
           case node
-          when Arel::Nodes::Between, Arel::Nodes::In, Arel::Nodes::NotIn, Arel::Nodes::Equality, Arel::Nodes::NotEqual, Arel::Nodes::LessThanOrEqual, Arel::Nodes::GreaterThanOrEqual
+          when Arel::Nodes::Between, Arel::Nodes::In, Arel::Nodes::NotIn, Arel::Nodes::Equality, Arel::Nodes::NotEqual, Arel::Nodes::LessThan, Arel::Nodes::LessThanOrEqual, Arel::Nodes::GreaterThan, Arel::Nodes::GreaterThanOrEqual
             subrelation = (node.left.kind_of?(Arel::Attributes::Attribute) ? node.left : node.right)
             columns.include?(subrelation.name.to_s)
           end
diff --git a/activerecord/test/cases/relations_test.rb b/activerecord/test/cases/relations_test.rb
index 0cf44388fa..b8e2041b6d 100644
--- a/activerecord/test/cases/relations_test.rb
+++ b/activerecord/test/cases/relations_test.rb
@@ -1657,6 +1657,10 @@ class RelationTest < ActiveRecord::TestCase
     assert_sql(/^((?!ORDER).)*$/) { Post.all.find_by(author_id: 2) }
   end
 
+  test "find_by requires at least one argument" do
+    assert_raises(ArgumentError) { Post.all.find_by }
+  end
+
   test "find_by! with hash conditions returns the first matching record" do
     assert_equal posts(:eager_other), Post.order(:id).find_by!(author_id: 2)
   end
@@ -1679,6 +1683,10 @@ class RelationTest < ActiveRecord::TestCase
     end
   end
 
+  test "find_by! requires at least one argument" do
+    assert_raises(ArgumentError) { Post.all.find_by! }
+  end
+
   test "loaded relations cannot be mutated by multi value methods" do
     relation = Post.all
     relation.to_a
diff --git a/activerecord/test/cases/scoping/default_scoping_test.rb b/activerecord/test/cases/scoping/default_scoping_test.rb
index 4137b20c4a..0dbc60940e 100644
--- a/activerecord/test/cases/scoping/default_scoping_test.rb
+++ b/activerecord/test/cases/scoping/default_scoping_test.rb
@@ -153,6 +153,18 @@ class DefaultScopingTest < ActiveRecord::TestCase
     assert_equal expected_7, received_7
   end
 
+  def test_unscope_comparison_where_clauses
+    # unscoped for WHERE (`developers`.`id` <= 2)
+    expected = Developer.order('salary DESC').collect(&:name)
+    received = DeveloperOrderedBySalary.where(id: -Float::INFINITY..2).unscope(where: :id).collect { |dev| dev.name }
+    assert_equal expected, received
+
+    # unscoped for WHERE (`developers`.`id` < 2)
+    expected = Developer.order('salary DESC').collect(&:name)
+    received = DeveloperOrderedBySalary.where(id: -Float::INFINITY...2).unscope(where: :id).collect { |dev| dev.name }
+    assert_equal expected, received
+  end
+
   def test_unscope_multiple_where_clauses
     expected = Developer.order('salary DESC').collect(&:name)
     received = DeveloperOrderedBySalary.where(name: 'Jamis').where(id: 1).unscope(where: [:name, :id]).collect(&:name)