Refactor pluck with multiple columns

Ensure it works with mix of symbols and strings, and with a select
clause possibly containing more than one column.

Also remove support for pluck with an array of columns, in favor of
passing the list of attributes:

    Model.pluck(:a, :b)

See comments: https://github.com/rails/rails/pull/6500#issuecomment-6030292

1 files changed, 16 insertions, 10 deletions

diff --git a/activerecord/test/cases/calculations_test.rb b/activerecord/test/cases/calculations_test.rb
index e86cf33b66..4df613488a 100644
--- a/activerecord/test/cases/calculations_test.rb
+++ b/activerecord/test/cases/calculations_test.rb
@@ -532,10 +532,6 @@ class CalculationsTest < ActiveRecord::TestCase
     assert_equal [50 + 53 + 55 + 60], Account.pluck('SUM(DISTINCT(credit_limit)) as credit_limit')
   end
 
-  def test_pluck_expects_a_multiple_selection_as_array
-    assert_raise(ArgumentError) { Account.pluck 'id, credit_limit' }
-  end
-
   def test_plucks_with_ids
     assert_equal Company.all.map(&:id).sort, Company.ids.sort
   end
@@ -551,14 +547,24 @@ class CalculationsTest < ActiveRecord::TestCase
     assert_equal [
       [1, "The First Topic"], [2, "The Second Topic of the day"],
       [3, "The Third Topic of the day"], [4, "The Fourth Topic of the day"]
-    ], Topic.order(:id).pluck([:id, :title])
+    ], Topic.order(:id).pluck(:id, :title)
     assert_equal [
       [1, "The First Topic", "David"], [2, "The Second Topic of the day", "Mary"],
       [3, "The Third Topic of the day", "Carl"], [4, "The Fourth Topic of the day", "Carl"]
-    ], Topic.order(:id).pluck([:id, :title, :author_name])
-    assert_equal [
-      [1, "The First Topic"], [2, "The Second Topic of the day"],
-      [3, "The Third Topic of the day"], [4, "The Fourth Topic of the day"]
-    ], Topic.order(:id).pluck(:id, :title)
+    ], Topic.order(:id).pluck(:id, :title, :author_name)
+  end
+
+  def test_pluck_with_multiple_columns_and_selection_clause
+    assert_equal [[1, 50], [2, 50], [3, 50], [4, 60], [5, 55], [6, 53]],
+      Account.pluck('id, credit_limit')
+  end
+
+  def test_pluck_with_multiple_columns_and_includes
+    Company.create!(:name => "test", :contracts => [Contract.new(:developer_id => 7)])
+    companies_and_developers = Company.order('companies.id').includes(:contracts).pluck(:name, :developer_id)
+
+    assert_equal Company.count, companies_and_developers.length
+    assert_equal ["37signals", nil], companies_and_developers.first
+    assert_equal ["test", 7], companies_and_developers.last
   end
 end