rename `Relation#uniq` to `Relation#distinct`. `#uniq` still works.

The similarity of `Relation#uniq` to `Array#uniq` is confusing. Since our
Relation API is close to SQL terms I renamed `#uniq` to `#distinct`.

There is no deprecation. `#uniq` and `#uniq!` are aliases and will continue
to work. I also updated the documentation to promote the use of `#distinct`.

8 files changed, 30 insertions, 7 deletions

diff --git a/activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb b/activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb
index 1b1b479f1a..84bdca3a97 100644
--- a/activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb
+++ b/activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb
@@ -316,7 +316,7 @@ class HasAndBelongsToManyAssociationsTest < ActiveRecord::TestCase
     dev.projects << projects(:active_record)
 
     assert_equal 3, dev.projects.size
-    assert_equal 1, dev.projects.uniq.size
+    assert_equal 1, dev.projects.distinct.size
   end
 
   def test_uniq_before_the_fact
diff --git a/activerecord/test/cases/associations/join_model_test.rb b/activerecord/test/cases/associations/join_model_test.rb
index 10ec33be75..c05481dd91 100644
--- a/activerecord/test/cases/associations/join_model_test.rb
+++ b/activerecord/test/cases/associations/join_model_test.rb
@@ -397,14 +397,14 @@ class AssociationsJoinModelTest < ActiveRecord::TestCase
   end
 
   def test_has_many_through_polymorphic_has_many
-    assert_equal taggings(:welcome_general, :thinking_general), authors(:david).taggings.uniq.sort_by { |t| t.id }
+    assert_equal taggings(:welcome_general, :thinking_general), authors(:david).taggings.distinct.sort_by { |t| t.id }
   end
 
   def test_include_has_many_through_polymorphic_has_many
     author            = Author.includes(:taggings).find authors(:david).id
     expected_taggings = taggings(:welcome_general, :thinking_general)
     assert_no_queries do
-      assert_equal expected_taggings, author.taggings.uniq.sort_by { |t| t.id }
+      assert_equal expected_taggings, author.taggings.distinct.sort_by { |t| t.id }
     end
   end
 
diff --git a/activerecord/test/cases/associations/nested_through_associations_test.rb b/activerecord/test/cases/associations/nested_through_associations_test.rb
index e355ed3495..e75d43bda8 100644
--- a/activerecord/test/cases/associations/nested_through_associations_test.rb
+++ b/activerecord/test/cases/associations/nested_through_associations_test.rb
@@ -410,7 +410,7 @@ class NestedThroughAssociationsTest < ActiveRecord::TestCase
 
     # Mary and Bob both have posts in misc, but they are the only ones.
     authors = Author.joins(:similar_posts).where('posts.id' => posts(:misc_by_bob).id)
-    assert_equal [authors(:mary), authors(:bob)], authors.uniq.sort_by(&:id)
+    assert_equal [authors(:mary), authors(:bob)], authors.distinct.sort_by(&:id)
 
     # Check the polymorphism of taggings is being observed correctly (in both joins)
     authors = Author.joins(:similar_posts).where('taggings.taggable_type' => 'FakeModel')
diff --git a/activerecord/test/cases/base_test.rb b/activerecord/test/cases/base_test.rb
index 9c73e4ca00..6f8290bdc3 100644
--- a/activerecord/test/cases/base_test.rb
+++ b/activerecord/test/cases/base_test.rb
@@ -1499,6 +1499,12 @@ class BasicsTest < ActiveRecord::TestCase
     assert_equal scope, Bird.uniq
   end
 
+  def test_distinct_delegates_to_scoped
+    scope = stub
+    Bird.stubs(:all).returns(mock(:distinct => scope))
+    assert_equal scope, Bird.distinct
+  end
+
   def test_table_name_with_2_abstract_subclasses
     assert_equal "photos", Photo.table_name
   end
diff --git a/activerecord/test/cases/calculations_test.rb b/activerecord/test/cases/calculations_test.rb
index be49e948fc..443a09f259 100644
--- a/activerecord/test/cases/calculations_test.rb
+++ b/activerecord/test/cases/calculations_test.rb
@@ -341,7 +341,8 @@ class CalculationsTest < ActiveRecord::TestCase
     assert_equal 5, Account.count(:firm_id)
   end
 
-  def test_count_with_uniq
+  def test_count_with_distinct
+    assert_equal 4, Account.select(:credit_limit).distinct.count
     assert_equal 4, Account.select(:credit_limit).uniq.count
   end
 
diff --git a/activerecord/test/cases/finder_test.rb b/activerecord/test/cases/finder_test.rb
index a9fa107749..e505fe9f18 100644
--- a/activerecord/test/cases/finder_test.rb
+++ b/activerecord/test/cases/finder_test.rb
@@ -82,7 +82,7 @@ class FinderTest < ActiveRecord::TestCase
 
   # ensures +exists?+ runs valid SQL by excluding order value
   def test_exists_with_order
-    assert Topic.order(:id).uniq.exists?
+    assert Topic.order(:id).distinct.exists?
   end
 
   def test_exists_with_includes_limit_and_empty_result
diff --git a/activerecord/test/cases/relation_test.rb b/activerecord/test/cases/relation_test.rb
index fd0b05cb77..9ca980fdf6 100644
--- a/activerecord/test/cases/relation_test.rb
+++ b/activerecord/test/cases/relation_test.rb
@@ -278,5 +278,17 @@ module ActiveRecord
       assert_equal [NullRelation], relation.extending_values
       assert relation.is_a?(NullRelation)
     end
+
+    test "distinct!" do
+      relation.distinct! :foo
+      assert_equal :foo, relation.distinct_value
+      assert_equal :foo, relation.uniq_value # deprecated access
+    end
+
+    test "uniq! was replaced by distinct!" do
+      relation.uniq! :foo
+      assert_equal :foo, relation.distinct_value
+      assert_equal :foo, relation.uniq_value # deprecated access
+    end
   end
 end
diff --git a/activerecord/test/cases/relations_test.rb b/activerecord/test/cases/relations_test.rb
index 26cbb03892..3de2c6ab58 100644
--- a/activerecord/test/cases/relations_test.rb
+++ b/activerecord/test/cases/relations_test.rb
@@ -492,6 +492,7 @@ class RelationTest < ActiveRecord::TestCase
     expected_taggings = taggings(:welcome_general, :thinking_general)
 
     assert_no_queries do
+      assert_equal expected_taggings, author.taggings.distinct.sort_by { |t| t.id }
       assert_equal expected_taggings, author.taggings.uniq.sort_by { |t| t.id }
     end
 
@@ -1269,7 +1270,7 @@ class RelationTest < ActiveRecord::TestCase
     assert_equal posts(:welcome),  comments(:greetings).post
   end
 
-  def test_uniq
+  def test_distinct
     tag1 = Tag.create(:name => 'Foo')
     tag2 = Tag.create(:name => 'Foo')
 
@@ -1277,11 +1278,14 @@ class RelationTest < ActiveRecord::TestCase
 
     assert_equal ['Foo', 'Foo'], query.map(&:name)
     assert_sql(/DISTINCT/) do
+      assert_equal ['Foo'], query.distinct.map(&:name)
       assert_equal ['Foo'], query.uniq.map(&:name)
     end
     assert_sql(/DISTINCT/) do
+      assert_equal ['Foo'], query.distinct(true).map(&:name)
       assert_equal ['Foo'], query.uniq(true).map(&:name)
     end
+    assert_equal ['Foo', 'Foo'], query.distinct(true).distinct(false).map(&:name)
     assert_equal ['Foo', 'Foo'], query.uniq(true).uniq(false).map(&:name)
   end