From 3dc9f8f1e120f0c95f67221ac0d1a9bac7b88cd4 Mon Sep 17 00:00:00 2001
From: Alexander Early <alexander.early@gmail.com>
Date: Thu, 6 Apr 2017 22:17:49 -0700
Subject: added tests for DLL, filter(), non-leaking empty()

---
 lib/internal/DoublyLinkedList.js | 28 +++++++++++++-
 mocha_test/linked_list.js        | 83 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 110 insertions(+), 1 deletion(-)
 create mode 100644 mocha_test/linked_list.js

diff --git a/lib/internal/DoublyLinkedList.js b/lib/internal/DoublyLinkedList.js
index 79c3bb5..0feea1b 100644
--- a/lib/internal/DoublyLinkedList.js
+++ b/lib/internal/DoublyLinkedList.js
@@ -23,7 +23,10 @@ DLL.prototype.removeLink = function(node) {
     return node;
 }
 
-DLL.prototype.empty = DLL;
+DLL.prototype.empty = function () {
+    while(this.head) this.shift();
+    return this;
+};
 
 DLL.prototype.insertAfter = function(node, newNode) {
     newNode.prev = node;
@@ -60,3 +63,26 @@ DLL.prototype.shift = function() {
 DLL.prototype.pop = function() {
     return this.tail && this.removeLink(this.tail);
 };
+
+DLL.prototype.toArray = function () {
+    var arr = Array(this.length);
+    var idx = 0;
+    var curr = this.head;
+    for(idx = 0; idx < this.length; idx++) {
+        arr[idx] = curr.data;
+        curr = curr.next;
+    }
+    return arr;
+}
+
+DLL.prototype.filter = function (testFn) {
+    var curr = this.head;
+    while(!!curr) {
+        var next = curr.next;
+        if (!testFn(curr)) {
+            this.removeLink(curr);
+        }
+        curr = next;
+    }
+    return this;
+}
diff --git a/mocha_test/linked_list.js b/mocha_test/linked_list.js
new file mode 100644
index 0000000..19cb155
--- /dev/null
+++ b/mocha_test/linked_list.js
@@ -0,0 +1,83 @@
+var DLL = require('../lib/internal/DoublyLinkedList').default;
+var expect = require('chai').expect;
+
+describe('DoublyLinkedList', function () {
+    it('toArray', function() {
+        var list = new DLL();
+        expect(list.toArray()).to.eql([]);
+
+        for (var i = 0; i < 5; i++) {
+            list.push({data: i});
+        }
+        expect(list.toArray()).to.eql([0, 1, 2, 3, 4]);
+    });
+
+    it('filter', function() {
+        var list = new DLL();
+
+        for (var i = 0; i < 5; i++) {
+            list.push({data: i});
+        }
+
+        list.filter(function (node) {
+            return node.data !== 3;
+        })
+
+        expect(list.toArray()).to.eql([0, 1, 2, 4]);
+    });
+
+    it('filter (head)', function() {
+        var list = new DLL();
+
+        for (var i = 0; i < 5; i++) {
+            list.push({data: i});
+        }
+
+        list.filter(function (node) {
+            return node.data !== 0;
+        })
+
+        expect(list.toArray()).to.eql([1, 2, 3, 4]);
+    });
+
+    it('filter (tail)', function() {
+        var list = new DLL();
+
+        for (var i = 0; i < 5; i++) {
+            list.push({data: i});
+        }
+
+        list.filter(function (node) {
+            return node.data !== 4;
+        })
+
+        expect(list.toArray()).to.eql([0, 1, 2, 3]);
+    });
+
+    it('filter (all)', function() {
+        var list = new DLL();
+
+        for (var i = 0; i < 5; i++) {
+            list.push({data: i});
+        }
+
+        list.filter(function (node) {
+            return node.data > 5;
+        })
+
+        expect(list.toArray()).to.eql([]);
+    });
+
+    it('empty', function() {
+        var list = new DLL();
+
+        for (var i = 0; i < 5; i++) {
+            list.push({data: i});
+        }
+
+        var empty = list.empty();
+
+        expect(list).to.equal(empty);
+        expect(list.toArray()).to.eql([]);
+    });
+});
-- 
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