4 files changed, 23 insertions, 17 deletions
diff --git a/activerecord/lib/active_record/core.rb b/activerecord/lib/active_record/core.rb
index d22806fbdf..2cbb8442a1 100644
--- a/activerecord/lib/active_record/core.rb
+++ b/activerecord/lib/active_record/core.rb
@@ -151,7 +151,7 @@ module ActiveRecord
       end
 
       def find_by(*args)
-        return super if current_scope || args.length > 1 || reflect_on_all_aggregations.any?
+        return super if current_scope || !(Hash === args.first) || reflect_on_all_aggregations.any?
 
         hash = args.first
 
diff --git a/activerecord/test/cases/base_test.rb b/activerecord/test/cases/base_test.rb
index 4c0b0c868a..fb535e74fc 100644
--- a/activerecord/test/cases/base_test.rb
+++ b/activerecord/test/cases/base_test.rb
@@ -1540,20 +1540,6 @@ class BasicsTest < ActiveRecord::TestCase
     assert_equal "", Company.new.description
   end
 
-  ["find_by", "find_by!"].each do |meth|
-    test "#{meth} delegates to scoped" do
-      record = stub
-
-      scope = mock
-      scope.expects(meth).with(:foo, :bar).returns(record)
-
-      klass = Class.new(ActiveRecord::Base)
-      klass.stubs(:all => scope)
-
-      assert_equal record, klass.public_send(meth, :foo, :bar)
-    end
-  end
-
   test "scoped can take a values hash" do
     klass = Class.new(ActiveRecord::Base)
     assert_equal ['foo'], klass.all.merge!(select: 'foo').select_values
diff --git a/activerecord/test/cases/finder_test.rb b/activerecord/test/cases/finder_test.rb
index b42a60fea5..9129dbaf63 100644
--- a/activerecord/test/cases/finder_test.rb
+++ b/activerecord/test/cases/finder_test.rb
@@ -1027,6 +1027,26 @@ class FinderTest < ActiveRecord::TestCase
     assert_nothing_raised(ActiveRecord::StatementInvalid) { Topic.offset("3").to_a }
   end
 
+  test "find_by with hash conditions returns the first matching record" do
+    assert_equal posts(:eager_other), Post.find_by(id: posts(:eager_other).id)
+  end
+
+  test "find_by with non-hash conditions returns the first matching record" do
+    assert_equal posts(:eager_other), Post.find_by("id = #{posts(:eager_other).id}")
+  end
+
+  test "find_by with multi-arg conditions returns the first matching record" do
+    assert_equal posts(:eager_other), Post.find_by('id = ?', posts(:eager_other).id)
+  end
+
+  test "find_by returns nil if the record is missing" do
+    assert_equal nil, Post.find_by("1 = 0")
+  end
+
+  test "find_by doesn't have implicit ordering" do
+    assert_sql(/^((?!ORDER).)*$/) { Post.find_by(id: posts(:eager_other).id) }
+  end
+
   protected
     def bind(statement, *vars)
       if vars.first.is_a?(Hash)
diff --git a/activerecord/test/cases/relations_test.rb b/activerecord/test/cases/relations_test.rb
index 88df997a2f..cc6a3888e3 100644
--- a/activerecord/test/cases/relations_test.rb
+++ b/activerecord/test/cases/relations_test.rb
@@ -1570,7 +1570,7 @@ class RelationTest < ActiveRecord::TestCase
   end
 
   test "find_by doesn't have implicit ordering" do
-    assert_sql(/^((?!ORDER).)*$/) { Post.find_by(author_id: 2) }
+    assert_sql(/^((?!ORDER).)*$/) { Post.all.find_by(author_id: 2) }
   end
 
   test "find_by! with hash conditions returns the first matching record" do
@@ -1586,7 +1586,7 @@ class RelationTest < ActiveRecord::TestCase
   end
 
   test "find_by! doesn't have implicit ordering" do
-    assert_sql(/^((?!ORDER).)*$/) { Post.find_by!(author_id: 2) }
+    assert_sql(/^((?!ORDER).)*$/) { Post.all.find_by!(author_id: 2) }
   end
 
   test "find_by! raises RecordNotFound if the record is missing" do