Refactor to @populated

Most of the tests use an @array with data already in it.

test/test_history_array.rb

@@ -3,56 +3,48 @@
 describe Pry::HistoryArray do
   before do
     @array = Pry::HistoryArray.new 10
+    @populated = @array.dup << 1 << 2 << 3 << 4
   end
 
   it 'should have a maximum size specifed at creation time' do
     @array.max_size.should == 10
   end
 
   it 'should be able to be added objects to' do
-    @array << 1 << 2 << 3
-    @array.size.should == 3
-    @array.to_a.should == [1, 2, 3]
+    @populated.size.should == 4
+    @populated.to_a.should == [1, 2, 3, 4]
   end
 
   it 'should be able to access single elements' do
-    @array << 1 << 2 << 3
-    @array[2].should == 3
+    @populated[2].should == 3
   end
 
   it 'should be able to access negative indices' do
-    @array << 1 << 2 << 3
-    @array[-1].should == 3
+    @populated[-1].should == 4
   end
 
   it 'should be able to access ranges' do
-    @array << 1 << 2 << 3 << 4
-    @array[1..2].should == [2, 3]
+    @populated[1..2].should == [2, 3]
   end
 
   it 'should be able to access ranges starting from a negative index' do
-    @array << 1 << 2 << 3 << 4
-    @array[-2..3].should == [3, 4]
+    @populated[-2..3].should == [3, 4]
   end
 
   it 'should be able to access ranges ending at a negative index' do
-    @array << 1 << 2 << 3 << 4
-    @array[2..-1].should == [3, 4]
+    @populated[2..-1].should == [3, 4]
   end
 
   it 'should be able to access ranges using only negative indices' do
-    @array << 1 << 2 << 3 << 4
-    @array[-2..-1].should == [3, 4]
+    @populated[-2..-1].should == [3, 4]
   end
 
   it 'should be able to use range where end is excluded' do
-    @array << 1 << 2 << 3 << 4
-    @array[-2...-1].should == [3]
+    @populated[-2...-1].should == [3]
   end
 
   it 'should be able to access slices using a size' do
-    @array << 1 << 2 << 3 << 4
-    @array[-3, 2].should == [2, 3]
+    @populated[-3, 2].should == [2, 3]
   end
 
   it 'should remove older entries' do