Fix in [] to be false, in [] to be true

This is in response to discussion on 62207fa

2 files changed, 14 insertions, 10 deletions

diff --git a/lib/arel/visitors/to_sql.rb b/lib/arel/visitors/to_sql.rb
index cb8df8329a..a350daa3da 100644
--- a/lib/arel/visitors/to_sql.rb
+++ b/lib/arel/visitors/to_sql.rb
@@ -370,11 +370,19 @@ key on UpdateManager using UpdateManager#key=
       end
 
       def visit_Arel_Nodes_In o
-        "#{visit o.left} IN (#{visit o.right})"
+        if Array === o.right && o.right.empty?
+          '1=0'
+        else
+          "#{visit o.left} IN (#{visit o.right})"
+        end
       end
 
       def visit_Arel_Nodes_NotIn o
-        "#{visit o.left} NOT IN (#{visit o.right})"
+        if Array === o.right && o.right.empty?
+          '1=1'
+        else
+          "#{visit o.left} NOT IN (#{visit o.right})"
+        end
       end
 
       def visit_Arel_Nodes_And o
diff --git a/test/visitors/test_to_sql.rb b/test/visitors/test_to_sql.rb
index 58eec1f63b..1caedacd45 100644
--- a/test/visitors/test_to_sql.rb
+++ b/test/visitors/test_to_sql.rb
@@ -167,11 +167,9 @@ module Arel
           }
         end
 
-        it "should return IN () when empty right which is invalid SQL" do
+        it "should return 1=0 when empty right which is always false" do
           node = @attr.in []
-          @visitor.accept(node).must_be_like %{
-            "users"."id" IN ()
-          }
+          @visitor.accept(node).must_equal '1=0'
         end
 
         it 'can handle two dot ranges' do
@@ -255,11 +253,9 @@ module Arel
           }
         end
 
-        it "should return NOT IN () when empty right which is invalid SQL" do
+        it "should return 1=1 when empty right which is always true" do
           node = @attr.not_in []
-          @visitor.accept(node).must_be_like %{
-            "users"."id" NOT IN ()
-          }
+          @visitor.accept(node).must_equal '1=1'
         end
 
         it 'can handle two dot ranges' do