deprecate `Relation#uniq` use `Relation#distinct` instead.

See #9683 for the reasons we switched to `distinct`.

Here is the discussion that triggered the actual deprecation #20198.

`uniq`, `uniq!` and `uniq_value` are still around.
They will be removed in the next minor release after Rails 5.

1 files changed, 13 insertions, 4 deletions

diff --git a/activerecord/test/cases/relation/mutation_test.rb b/activerecord/test/cases/relation/mutation_test.rb
index 45ead08bd5..2f2987e42d 100644
--- a/activerecord/test/cases/relation/mutation_test.rb
+++ b/activerecord/test/cases/relation/mutation_test.rb
@@ -81,7 +81,7 @@ module ActiveRecord
       assert_equal [], relation.extending_values
     end
 
-    (Relation::SINGLE_VALUE_METHODS - [:lock, :reordering, :reverse_order, :create_with]).each do |method|
+    (Relation::SINGLE_VALUE_METHODS - [:lock, :reordering, :reverse_order, :create_with, :uniq]).each do |method|
       test "##{method}!" do
         assert relation.public_send("#{method}!", :foo).equal?(relation)
         assert_equal :foo, relation.public_send("#{method}_value")
@@ -153,13 +153,22 @@ module ActiveRecord
     test 'distinct!' do
       relation.distinct! :foo
       assert_equal :foo, relation.distinct_value
-      assert_equal :foo, relation.uniq_value # deprecated access
+
+      assert_deprecated do
+        assert_equal :foo, relation.uniq_value # deprecated access
+      end
     end
 
     test 'uniq! was replaced by distinct!' do
-      relation.uniq! :foo
+      assert_deprecated(/use distinct! instead/) do
+        relation.uniq! :foo
+      end
+
+      e = assert_deprecated(/use distinct_value instead/) do
+        assert_equal :foo, relation.uniq_value # deprecated access
+      end
+
       assert_equal :foo, relation.distinct_value
-      assert_equal :foo, relation.uniq_value # deprecated access
     end
   end
 end