Add ActiveRecord::Relation#uniq for toggling DISTINCT in the SQL query

3 files changed, 23 insertions, 1 deletions

diff --git a/activerecord/test/cases/base_test.rb b/activerecord/test/cases/base_test.rb
index 12c1cfb30e..fdb656fe13 100644
--- a/activerecord/test/cases/base_test.rb
+++ b/activerecord/test/cases/base_test.rb
@@ -1935,4 +1935,10 @@ class BasicsTest < ActiveRecord::TestCase
     dev.update_attribute(:updated_at, nil)
     assert_match(/\/#{dev.id}$/, dev.cache_key)
   end
+
+  def test_uniq_delegates_to_scoped
+    scope = stub
+    Bird.stubs(:scoped).returns(mock(:uniq => scope))
+    assert_equal scope, Bird.uniq
+  end
 end
diff --git a/activerecord/test/cases/relation_test.rb b/activerecord/test/cases/relation_test.rb
index b23ead6feb..715a378431 100644
--- a/activerecord/test/cases/relation_test.rb
+++ b/activerecord/test/cases/relation_test.rb
@@ -20,7 +20,7 @@ module ActiveRecord
     end
 
     def test_single_values
-      assert_equal [:limit, :offset, :lock, :readonly, :from, :reorder, :reverse_order].map(&:to_s).sort,
+      assert_equal [:limit, :offset, :lock, :readonly, :from, :reorder, :reverse_order, :uniq].map(&:to_s).sort,
         Relation::SINGLE_VALUE_METHODS.map(&:to_s).sort
     end
 
diff --git a/activerecord/test/cases/relations_test.rb b/activerecord/test/cases/relations_test.rb
index 95408a5f29..bf1eb6386a 100644
--- a/activerecord/test/cases/relations_test.rb
+++ b/activerecord/test/cases/relations_test.rb
@@ -1148,4 +1148,20 @@ class RelationTest < ActiveRecord::TestCase
     assert_equal posts(:thinking), comments(:more_greetings).post
     assert_equal posts(:welcome),  comments(:greetings).post
   end
+
+  def test_uniq
+    tag1 = Tag.create(:name => 'Foo')
+    tag2 = Tag.create(:name => 'Foo')
+
+    query = Tag.select(:name).where(:id => [tag1.id, tag2.id])
+
+    assert_equal ['Foo', 'Foo'], query.map(&:name)
+    assert_sql(/DISTINCT/) do
+      assert_equal ['Foo'], query.uniq.map(&:name)
+    end
+    assert_sql(/DISTINCT/) do
+      assert_equal ['Foo'], query.uniq(true).map(&:name)
+    end
+    assert_equal ['Foo', 'Foo'], query.uniq(true).uniq(false).map(&:name)
+  end
 end