From 90737a5602f594e0252656994bb5ee6ec77b94e2 Mon Sep 17 00:00:00 2001
From: Francisco Rojas <frojas@groupon.com>
Date: Thu, 24 Dec 2015 13:38:43 -0800
Subject: [PATCH 1/2] Add excheck as dependency

* Also, commit mix.lock file
---
 config/config.exs    | 2 ++
 mix.exs              | 5 ++++-
 mix.lock             | 2 ++
 test/test_helper.exs | 1 +
 4 files changed, 9 insertions(+), 1 deletion(-)
 create mode 100644 mix.lock

diff --git a/config/config.exs b/config/config.exs
index 6dfa82f..dff0e79 100644
--- a/config/config.exs
+++ b/config/config.exs
@@ -2,6 +2,8 @@
 # and its dependencies with the aid of the Mix.Config module.
 use Mix.Config
 
+config :excheck, :number_iterations, 200
+
 # This configuration is loaded before any dependency and is restricted
 # to this project. If another project depends on this project, this
 # file won't be loaded nor affect the parent project. For this reason,
diff --git a/mix.exs b/mix.exs
index f960a17..44657d1 100644
--- a/mix.exs
+++ b/mix.exs
@@ -27,7 +27,10 @@ defmodule Heapq.Mixfile do
   #
   # Type `mix help deps` for more examples and options
   defp deps do
-    []
+    [
+      {:excheck, "~> 0.3", only: :test},
+      {:triq, github: "krestenkrab/triq", only: :test}
+    ]
   end
 
   defp package do
diff --git a/mix.lock b/mix.lock
new file mode 100644
index 0000000..b1e612c
--- /dev/null
+++ b/mix.lock
@@ -0,0 +1,2 @@
+%{"excheck": {:hex, :excheck, "0.3.2"},
+  "triq": {:git, "https://github.com/krestenkrab/triq.git", "c7306b8eaea133d52140cb828817efb5e50a3d52", []}}
diff --git a/test/test_helper.exs b/test/test_helper.exs
index 869559e..b1a1d61 100644
--- a/test/test_helper.exs
+++ b/test/test_helper.exs
@@ -1 +1,2 @@
+ExCheck.start
 ExUnit.start()

From f53a9fecd6e54951dec7b141b353dceff7d8f705 Mon Sep 17 00:00:00 2001
From: Francisco Rojas <frojas@groupon.com>
Date: Thu, 24 Dec 2015 13:39:51 -0800
Subject: [PATCH 2/2] Add propery based test

properties:
  * empty?
  * find min element
  * elements are pop in a sorted fashion
  * to_list generate a sorted list
  * size
---
 test/heapq_prop_test.exs | 58 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)
 create mode 100644 test/heapq_prop_test.exs

diff --git a/test/heapq_prop_test.exs b/test/heapq_prop_test.exs
new file mode 100644
index 0000000..1287cff
--- /dev/null
+++ b/test/heapq_prop_test.exs
@@ -0,0 +1,58 @@
+defmodule HeapQueue.PropTest do
+  use ExUnit.Case, async: false
+  use ExCheck
+
+  property :empty? do
+    for_all {x, y} in {int, int} do
+      q = HeapQueue.push(HeapQueue.new(), x, y)
+      {{:value, ^x, value}, q} = HeapQueue.pop(q)
+      value == y && HeapQueue.empty?(q)
+    end
+  end
+
+  property :find_min do
+    for_all {x, y} in such_that({xx, yy} in {int, int} when xx < yy) do
+      q = HeapQueue.new()
+        |> HeapQueue.push_value(x)
+        |> HeapQueue.push_value(y)
+
+      {{:value, value}, _q} = HeapQueue.pop_value(q)
+      value == x
+    end
+  end
+
+  def sorted?(q) do
+    if(HeapQueue.empty?(q)) do
+      true
+    else
+      {{:value, m}, q} = HeapQueue.pop_value(q)
+      if(HeapQueue.empty?(q)) do
+        true
+      else
+        {{:value, value}, _q} = HeapQueue.pop_value(q)
+        (m <= value && sorted?(q))
+      end
+    end
+  end
+
+  property :sorted do
+    for_all xs in list(int) do
+      q = Enum.reduce(xs, HeapQueue.new(), &(HeapQueue.push_value(&2, &1)))
+      sorted?(q)
+    end
+  end
+
+  property :to_list_sorted do
+    for_all xs in list(int) do
+      q = Enum.reduce(xs, HeapQueue.new(), &(HeapQueue.push_value(&2, &1)))
+      HeapQueue.to_list_of_values(q) == Enum.sort(xs)
+    end
+  end
+
+  property :size do
+    for_all xs in list(int) do
+      q = Enum.reduce(xs, HeapQueue.new(), &(HeapQueue.push_value(&2, &1)))
+      HeapQueue.size(q) == Enum.count(xs)
+    end
+  end
+end