Relation: Make where return a fresh relation to avoid leaking scopes

lib/active_hash/relation.rb

@@ -11,16 +11,14 @@ def initialize(klass, all_records, query_hash = nil)
       self.klass = klass
       self.all_records = all_records
       self.query_hash = query_hash
-      self.records_dirty = false
-      self
     end
 
     def where(query_hash = :chain)
-      return ActiveHash::Base::WhereChain.new(self) if query_hash == :chain
-
-      self.records_dirty = true unless query_hash.nil? || query_hash.keys.empty?
-      self.query_hash.merge!(query_hash || {})
-      self
+      if query_hash == :chain
+        ActiveHash::Base::WhereChain.new(self)
+      else
+        self.class.new(klass, all_records, self.query_hash.merge(query_hash || {}))
+      end
     end
 
     def all(options = {})
@@ -111,22 +109,21 @@ def method_missing(method_name, *args)
       instance_exec(*args, &self.klass.scopes[method_name])
     end
 
-    attr_reader :query_hash, :klass, :all_records, :records_dirty
+    attr_reader :query_hash, :klass, :all_records
 
     private
 
-    attr_writer :query_hash, :klass, :all_records, :records_dirty
+    attr_writer :query_hash, :klass, :all_records
 
     def records
-      if !defined?(@records) || @records.nil? || records_dirty
+      if !defined?(@records) || @records.nil?
         reload
       else
         @records
       end
     end
 
     def filter_all_records_by_query_hash
-      self.records_dirty = false
       return all_records if query_hash.blank?
 
       # use index if searching by id

spec/active_hash/base_spec.rb

@@ -236,6 +236,14 @@ class Region < ActiveHash::Base
       Country.where(:language => 'English').all? { |country| expect(country).to be_kind_of(Country) }
     end
 
+    it "doesn't affect the original" do
+      countries = Country.where(:language => 'English')
+
+      expect(countries.size).to eq 2
+      expect(countries.where(name: "US").size).to eq 1
+      expect(countries.size).to eq 2
+    end
+
     it "populates the data correctly" do
       records = Country.where(:language => 'English')
       expect(records.first.id).to eq(1)