From 1a40be02113287d9a003f8224e91b9f623857f4b Mon Sep 17 00:00:00 2001
From: Ben Woosley <ben.woosley@gmail.com>
Date: Tue, 3 Sep 2013 21:46:33 -0700
Subject: Deprecate the delegation of Array bang methods in
 ActiveRecord::Delegation

The primary means of returning results for Array bang methods is to modify
the array in-place. When you call these methods on a relation, that
array is created, modified, and then thrown away. Only the secondary
return value is exposed to the caller.

Removing this delegation is a straight-forward way to reduce user error
by forcing callers to first explicitly call #to_a in order to expose
the array to be acted on by the bang method.
---
 .../test/cases/relation/delegation_test.rb         | 97 ++++++++++++++++++++++
 1 file changed, 97 insertions(+)
 create mode 100644 activerecord/test/cases/relation/delegation_test.rb

(limited to 'activerecord/test/cases')

diff --git a/activerecord/test/cases/relation/delegation_test.rb b/activerecord/test/cases/relation/delegation_test.rb
new file mode 100644
index 0000000000..71ade0bcc2
--- /dev/null
+++ b/activerecord/test/cases/relation/delegation_test.rb
@@ -0,0 +1,97 @@
+require 'cases/helper'
+require 'models/post'
+require 'models/comment'
+
+module ActiveRecord
+  class DelegationTest < ActiveRecord::TestCase
+    fixtures :posts
+
+    def assert_responds(target, method)
+      assert target.respond_to?(method)
+      assert_nothing_raised do
+        case target.to_a.method(method).arity
+        when 0
+          target.send(method)
+        when -1
+          if method == :shuffle!
+            target.send(method)
+          else
+            target.send(method, 1)
+          end
+        else
+          raise NotImplementedError
+        end
+      end
+    end
+  end
+
+  class DelegationAssociationTest < DelegationTest
+    def target
+      Post.first.comments
+    end
+
+    [:map, :collect].each do |method|
+      test "##{method} is delgated" do
+        assert_responds(target, method)
+        assert_equal(target.pluck(:body), target.send(method) {|post| post.body })
+      end
+
+      test "##{method}! is not delgated" do
+        assert_deprecated do
+          assert_responds(target, "#{method}!")
+        end
+      end
+    end
+
+    [:compact!, :flatten!, :reject!, :reverse!, :rotate!,
+      :shuffle!, :slice!, :sort!, :sort_by!].each do |method|
+      test "##{method} delegation is deprecated" do
+        assert_deprecated do
+          assert_responds(target, method)
+        end
+      end
+    end
+
+    [:select!, :uniq!].each do |method|
+      test "##{method} is implemented" do
+        assert_responds(target, method)
+      end
+    end
+  end
+
+  class DelegationRelationTest < DelegationTest
+    def target
+      Comment.where.not(body: nil)
+    end
+
+    [:map, :collect].each do |method|
+      test "##{method} is delgated" do
+        assert_responds(target, method)
+        assert_equal(target.pluck(:body), target.send(method) {|post| post.body })
+      end
+
+      test "##{method}! is not delgated" do
+        assert_deprecated do
+          assert_responds(target, "#{method}!")
+        end
+      end
+    end
+
+    [:compact!, :flatten!, :reject!, :reverse!, :rotate!,
+      :shuffle!, :slice!, :sort!, :sort_by!].each do |method|
+      test "##{method} delegation is deprecated" do
+        assert_deprecated do
+          assert_responds(target, method)
+        end
+      end
+    end
+
+    [:select!, :uniq!].each do |method|
+      test "##{method} is triggers an immutable error" do
+        assert_raises ActiveRecord::ImmutableRelation do
+          assert_responds(target, method)
+        end
+      end
+    end
+  end
+end
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