From b01ed021eaee519c035b707cfdfb77501e32a7bb Mon Sep 17 00:00:00 2001
From: Slava Kim <slava@meteor.com>
Date: Fri, 21 Feb 2014 17:48:22 -0800
Subject: [PATCH] New giant randomized test with self-checks

---
 packages/binary-heap/binary-heap-tests.js | 34 +++++++++++++++++++++++
 packages/binary-heap/max-heap.js          |  9 ++++++
 2 files changed, 43 insertions(+)

diff --git a/packages/binary-heap/binary-heap-tests.js b/packages/binary-heap/binary-heap-tests.js
index 9a709b6fe4..496af9c0c3 100644
--- a/packages/binary-heap/binary-heap-tests.js
+++ b/packages/binary-heap/binary-heap-tests.js
@@ -81,3 +81,37 @@ Tinytest.add("binary-heap - min-max heap tests", function (test) {
   test.equal(h.minElementId(), "a");
 });
 
+Tinytest.add("binary-heap - big test for min-max-heap", function (test) {
+  var N = 500;
+  var positiveNumbers = _.shuffle(_.range(1, N + 1));
+  var negativeNumbers = _.shuffle(_.range(-1, -N - 1, -1));
+  var allNumbers = positiveNumbers.concat(negativeNumbers);
+
+  var heap = new MinMaxHeap(function (a, b) { return a-b; });
+  var output = [];
+
+  _.each(allNumbers, function (n) {
+    heap.set(n, n);
+    heap._selfCheck();
+    heap._minHeap._selfCheck();
+  });
+
+  allNumbers = _.shuffle(allNumbers);
+  _.each(allNumbers, function (n) {
+    heap.set(-n, n);
+    heap._selfCheck();
+    heap._minHeap._selfCheck();
+  });
+
+  _.times(positiveNumbers.length + negativeNumbers.length, function () {
+    var minId = heap.minElementId();
+    output.push(heap.get(minId));
+    heap.remove(minId);
+    heap._selfCheck(); heap._minHeap._selfCheck();
+  });
+
+  allNumbers.sort(function (a, b) { return a-b; });
+
+  test.equal(output, allNumbers);
+});
+
diff --git a/packages/binary-heap/max-heap.js b/packages/binary-heap/max-heap.js
index 891e9b3771..2d70e3509d 100644
--- a/packages/binary-heap/max-heap.js
+++ b/packages/binary-heap/max-heap.js
@@ -195,6 +195,15 @@ _.extend(MaxHeap.prototype, {
   maxElementId: function () {
     var self = this;
     return self.size() ? self._heap[0].id : null;
+  },
+
+  _selfCheck: function () {
+    var self = this;
+    for (var i = 1; i < self._heap.length; i++)
+      if (self._maxIndex(parentIdx(i), i) !== parentIdx(i))
+          throw new Error("An item with id " + self._heap[i].id +
+                          " has a parent younger than him: " +
+                          self._heap[parentIdx(i)].id);
   }
 });