ring: fix swap parts of array in to_a and index access

lib/pry/ring.rb

@@ -57,10 +57,7 @@ class Pry
         return @buffer[(count + index) % max_size] if index.is_a?(Integer)
         return @buffer[index] if count <= max_size
 
-        # Swap parts of array when the array turns page and starts overwriting
-        # from the beginning, then apply the range.
-        last_part = @buffer.slice([index.end, max_size - 1].min, count % max_size)
-        (last_part + (@buffer - last_part))[index]
+        transpose_buffer_tail[index]
       end
     end
 
@@ -68,8 +65,7 @@ class Pry
     def to_a
       return @buffer.dup if count <= max_size
 
-      last_part = @buffer.slice(count % max_size, @buffer.size)
-      last_part + (@buffer - last_part)
+      transpose_buffer_tail
     end
 
     # Clear the buffer and reset count.
@@ -80,5 +76,12 @@ class Pry
         @count = 0
       end
     end
+
+    private
+
+    def transpose_buffer_tail
+      tail = @buffer.slice(count % max_size, @buffer.size)
+      tail.concat @buffer.slice(0, count % max_size)
+    end
   end
 end

spec/ring_spec.rb

@@ -13,6 +13,11 @@ describe Pry::Ring do
       ring << 1 << 2 << 3 << 4 << 5
       expect(ring.to_a).to eq([3, 4, 5])
     end
+
+    it "keeps duplicate elements" do
+      ring << 1 << 1 << 1 << 1
+      expect(ring.to_a).to eq([1, 1, 1])
+    end
   end
 
   describe "#[]" do
@@ -54,6 +59,10 @@ describe Pry::Ring do
         expect(ring[-3]).to eq(3)
       end
 
+      it "returns the first element when accessed through 0..0" do
+        expect(ring[0..0]).to eq([3])
+      end
+
       it "reads elements via inclusive range" do
         expect(ring[1..2]).to eq([4, 5])
         expect(ring[-2..-1]).to eq([4, 5])