Change the interface of having to match that of where

These two clauses have nearly identical semantics with regards to how
they would be constructed as an AST. It doesn't make sense for their
interfaces to be separate.

lib/arel/nodes/select_core.rb

@@ -2,7 +2,7 @@ module Arel
   module Nodes
     class SelectCore < Arel::Nodes::Node
       attr_accessor :top, :projections, :wheres, :groups, :windows
-      attr_accessor :having, :source, :set_quantifier
+      attr_accessor :havings, :source, :set_quantifier
 
       def initialize
         super()
@@ -14,7 +14,7 @@ module Arel
         @projections    = []
         @wheres         = []
         @groups         = []
-        @having         = nil
+        @havings        = []
         @windows        = []
       end
 
@@ -35,14 +35,14 @@ module Arel
         @projections = @projections.clone
         @wheres      = @wheres.clone
         @groups      = @groups.clone
-        @having      = @having.clone if @having
+        @havings     = @havings.clone
         @windows     = @windows.clone
       end
 
       def hash
         [
           @source, @top, @set_quantifier, @projections,
-          @wheres, @groups, @having, @windows
+          @wheres, @groups, @havings, @windows
         ].hash
       end
 
@@ -54,7 +54,7 @@ module Arel
           self.projections == other.projections &&
           self.wheres == other.wheres &&
           self.groups == other.groups &&
-          self.having == other.having &&
+          self.havings == other.havings &&
           self.windows == other.windows
       end
       alias :== :eql?

lib/arel/nodes/unary.rb

@@ -23,7 +23,6 @@ module Arel
     %w{
       Bin
       Group
-      Having
       Limit
       Not
       Offset

lib/arel/select_manager.rb

@@ -118,8 +118,8 @@ module Arel
       join(relation, Nodes::OuterJoin)
     end
 
-    def having *exprs
-      @ctx.having = Nodes::Having.new(collapse(exprs, @ctx.having))
+    def having expr
+      @ctx.havings << expr
       self
     end
 

lib/arel/visitors/depth_first.rb

@@ -146,7 +146,7 @@ module Arel
         visit o.wheres
         visit o.groups
         visit o.windows
-        visit o.having
+        visit o.havings
       end
 
       def visit_Arel_Nodes_SelectStatement o

lib/arel/visitors/informix.rb

@@ -34,8 +34,13 @@ module Arel
           collector = inject_join o.groups, collector, ", "
         end
 
-        maybe_visit o.having, collector
+        if o.havings.any?
+          collector << " HAVING "
+          collector = inject_join o.havings, collector, " AND "
+        end
+        collector
       end
+
       def visit_Arel_Nodes_Offset o, collector
         collector << "SKIP "
         visit o.expr, collector

lib/arel/visitors/to_sql.rb

@@ -265,7 +265,10 @@ module Arel
           end
         end
 
-        collector = maybe_visit o.having, collector
+        unless o.havings.empty?
+          collector << " HAVING "
+          inject_join o.havings, collector, AND
+        end
 
         unless o.windows.empty?
           collector << WINDOW
@@ -404,11 +407,6 @@ module Arel
         end
       end
 
-      def visit_Arel_Nodes_Having o, collector
-        collector << "HAVING "
-        visit o.expr, collector
-      end
-
       def visit_Arel_Nodes_Offset o, collector
         collector << "OFFSET "
         visit o.expr, collector

test/nodes/test_select_core.rb

@@ -34,14 +34,14 @@ module Arel
         core1.wheres      = %w[g h i]
         core1.groups      = %w[j k l]
         core1.windows     = %w[m n o]
-        core1.having      = %w[p q r]
+        core1.havings     = %w[p q r]
         core2 = SelectCore.new
         core2.froms       = %w[a b c]
         core2.projections = %w[d e f]
         core2.wheres      = %w[g h i]
         core2.groups      = %w[j k l]
         core2.windows     = %w[m n o]
-        core2.having      = %w[p q r]
+        core2.havings     = %w[p q r]
         array = [core1, core2]
         assert_equal 1, array.uniq.size
       end
@@ -53,14 +53,14 @@ module Arel
         core1.wheres      = %w[g h i]
         core1.groups      = %w[j k l]
         core1.windows     = %w[m n o]
-        core1.having      = %w[p q r]
+        core1.havings     = %w[p q r]
         core2 = SelectCore.new
         core2.froms       = %w[a b c]
         core2.projections = %w[d e f]
         core2.wheres      = %w[g h i]
         core2.groups      = %w[j k l]
         core2.windows     = %w[m n o]
-        core2.having      = %w[l o l]
+        core2.havings     = %w[l o l]
         array = [core1, core2]
         assert_equal 2, array.uniq.size
       end

test/test_select_manager.rb

@@ -111,22 +111,22 @@ module Arel
         it 'converts strings to SQLLiterals' do
           table   = Table.new :users
           mgr = table.from
-          mgr.having 'foo'
+          mgr.having Arel.sql('foo')
           mgr.to_sql.must_be_like %{ SELECT FROM "users" HAVING foo }
         end
 
         it 'can have multiple items specified separately' do
           table = Table.new :users
           mgr = table.from
-          mgr.having 'foo'
-          mgr.having 'bar'
+          mgr.having Arel.sql('foo')
+          mgr.having Arel.sql('bar')
           mgr.to_sql.must_be_like %{ SELECT FROM "users" HAVING foo AND bar }
         end
 
-        it 'can have multiple items specified together' do
+        it 'can receive any node' do
           table = Table.new :users
           mgr = table.from
-          mgr.having 'foo', 'bar'
+          mgr.having Arel::Nodes::And.new([Arel.sql('foo'), Arel.sql('bar')])
           mgr.to_sql.must_be_like %{ SELECT FROM "users" HAVING foo AND bar }
         end
       end

test/visitors/test_depth_first.rb

@@ -30,7 +30,6 @@ module Arel
         Arel::Nodes::Grouping,
         Arel::Nodes::Offset,
         Arel::Nodes::Ordering,
-        Arel::Nodes::Having,
         Arel::Nodes::StringJoin,
         Arel::Nodes::UnqualifiedColumn,
         Arel::Nodes::Top,
@@ -206,7 +205,7 @@ module Arel
         core.wheres << :c
         core.groups << :d
         core.windows << :e
-        core.having = :f
+        core.havings << :f
 
         @visitor.accept core
         assert_equal [
@@ -216,7 +215,7 @@ module Arel
           :c, core.wheres,
           :d, core.groups,
           :e, core.windows,
-          :f,
+          :f, core.havings,
           core], @collector.calls
       end
 

test/visitors/test_dot.rb

@@ -34,7 +34,6 @@ module Arel
         Arel::Nodes::Grouping,
         Arel::Nodes::Offset,
         Arel::Nodes::Ordering,
-        Arel::Nodes::Having,
         Arel::Nodes::UnqualifiedColumn,
         Arel::Nodes::Top,
         Arel::Nodes::Limit,