Commit a122fdf

@@ -0,0 +1,13 @@
+class DynamicArrayStack
+  def initialize(items = [])
+    @items = items
+  end
+
+  def pop
+    @items.pop
+  end
+
+  def push(item)
+    @items.push(item)
+  end
+end

@@ -1,14 +0,0 @@
-class InsertionSort
-  def sort(items)
-    items.size.times do |n|
-      j = n
-      while j >= 0 do
-        if (items[j] <=> items[j+1]) == 1
-          items[j], items[j+1] = items[j+1], items[j]
-        end
-        j-=1
-      end
-    end
-    items
-  end
-end

@@ -0,0 +1,30 @@
+require "spec_helper"
+
+describe DynamicArrayStack do
+  let(:sut) { DynamicArrayStack.new }
+
+  context "when there is nothing on the stack" do
+    it "should be able to pop off nil" do
+      sut.pop.should be_nil
+    end
+  end
+
+  context "when there is one item on the stack" do
+    it "should be able to pop it off" do
+      n = rand
+      sut.push(n)
+      sut.pop.should == n
+    end
+  end
+
+  context "when there are multiple items on the stack" do
+    it "should pop each one off in the right order" do
+      (0..10).each do |n|
+        sut.push(n)
+      end
+      (10..0).each do |n|
+        sut.pop.should == n
+      end
+    end
+  end
+end

@@ -5,3 +5,4 @@ require_relative '../lib/sorting/quick_sort'
 require_relative '../lib/sorting/merge_sort'
 
 require_relative '../lib/data_structures/linked_list_stack'
+require_relative '../lib/data_structures/dynamic_array_stack'