Add equality to ALL THE THINGS (that matter)

People are often trying to use ARel nodes inside ActiveRecord, and when
they do so, lots of things can break, because ActiveRecord relies on
Array#uniq and sometimes hash key equality to handle values that end up
in wheres, havings, etc. By implementing equality for all the nodes, we
should hopefully be able to prevent any nodes (even nodes containing
other nodes) from failing an equality check they should otherwise pass,
and alleviate many of these errors.

Fixes #130

1 files changed, 24 insertions, 0 deletions

diff --git a/test/test_table.rb b/test/test_table.rb
index 1035540513..5db8cdd6c0 100644
--- a/test/test_table.rb
+++ b/test/test_table.rb
@@ -180,5 +180,29 @@ module Arel
         end
       end
     end
+
+    describe 'equality' do
+      it 'is equal with equal ivars' do
+        relation1 = Table.new(:users, 'vroom')
+        relation1.aliases     = %w[a b c]
+        relation1.table_alias = 'zomg'
+        relation2 = Table.new(:users, 'vroom')
+        relation2.aliases     = %w[a b c]
+        relation2.table_alias = 'zomg'
+        array = [relation1, relation2]
+        assert_equal 1, array.uniq.size
+      end
+
+      it 'is not equal with different ivars' do
+        relation1 = Table.new(:users, 'vroom')
+        relation1.aliases     = %w[a b c]
+        relation1.table_alias = 'zomg'
+        relation2 = Table.new(:users, 'vroom')
+        relation2.aliases     = %w[x y z]
+        relation2.table_alias = 'zomg'
+        array = [relation1, relation2]
+        assert_equal 2, array.uniq.size
+      end
+    end
   end
 end