text: /**
  * @license Apache-2.0
  *
  * Copyright (c) 2018 The Stdlib Authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *    http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
  
  'use strict';
  
  // MODULES //
  
  var tape = require( 'tape' );
  var proxyquire = require( 'proxyquire' );
  var instanceOf = require( '@stdlib/assert-instance-of' );
  var iteratorSymbol = require( '@stdlib/symbol-iterator' );
  var LinkedList = require( './../lib' );
  
  
  // TESTS //
  
  tape( 'main export is a function', function test( t ) {
  	t.ok( true, __filename );
  	t.strictEqual( typeof LinkedList, 'function', 'main export is a function' );
  	t.end();
  });
  
  tape( 'the function is a constructor', function test( t ) {
  	var list = new LinkedList();
  	t.strictEqual( instanceOf( list, LinkedList ), true, 'returns an instance' );
  	t.end();
  });
  
  tape( 'the constructor does not require the `new` keyword', function test( t ) {
  	var linkedList;
  	var list;
  
  	linkedList = LinkedList;
  	list = linkedList();
  	t.strictEqual( instanceOf( list, LinkedList ), true, 'returns an instance' );
  	t.end();
  });
  
  tape( 'the constructor returns a linked list instance which has a `clear` method for removing all elements in the list', function test( t ) {
  	var list;
  
  	list = new LinkedList();
  	list.push( 'foo' );
  	list.push( 'bar' );
  	list.push( 'beep' );
  	list.push( 'boop' );
  
  	t.strictEqual( list.length, 4, 'returns expected value' );
  	t.strictEqual( list.first().value, 'foo', 'returns expected value' );
  	t.strictEqual( list.last().value, 'boop', 'returns expected value' );
  	t.deepEqual( list.toArray(), [ 'foo', 'bar', 'beep', 'boop' ], 'returns expected value' );
  
  	list.clear();
  
  	t.strictEqual( list.length, 0, 'returns expected value' );
  	t.strictEqual( list.first(), void 0, 'returns expected value' );
  	t.strictEqual( list.last(), void 0, 'returns expected value' );
  	t.deepEqual( list.toArray(), [], 'returns expected value' );
  
  	t.end();
  });
  
  tape( 'the constructor returns a linked list instance which has a `first` method for returning the first list node', function test( t ) {
  	var list;
  
  	list = new LinkedList();
  	t.strictEqual( list.first(), void 0, 'returns expected value' );
  
  	list.push( 'foo' );
  	t.strictEqual( list.first().value, 'foo', 'returns expected value' );
  
  	list.push( 'bar' );
  	t.strictEqual( list.first().value, 'foo', 'returns expected value' );
  
  	list.pop();
  	t.strictEqual( list.first().value, 'foo', 'returns expected value' );
  
  	list.pop();
  	t.strictEqual( list.first(), void 0, 'returns expected value' );
  
  	t.end();
  });
  
  tape( 'the constructor returns a list instance which has an `insert` method for inserting a value into the list', function test( t ) {
  	var list;
  
  	list = new LinkedList();
  
  	list.push( 'foo' );
  	t.strictEqual( list.length, 1, 'returns expected value' );
  
  	list.insert( list.first(), 'bar' );
  	t.strictEqual( list.length, 2, 'returns expected value' );
  
  	// Supports chaining:
  	list.insert( list.first(), 'beep' )
  		.insert( list.first().next, 'boop' )
  		.insert( list.last(), 'bop' );
  
  	t.strictEqual( list.length, 5, 'returns expected value' );
  
  	t.end();
  });
  
  tape( 'the constructor returns a list instance which has an `insert` method which throws an error if provided a node which is not in the list', function test( t ) {
  	var list;
  	var n;
  
  	list = new LinkedList();
  
  	list.push( 'foo' );
  	list.push( 'bar' );
  	list.push( 'beep' );
  	list.push( 'boop' );
  
  	n = list.first().next;
  	list.remove( n );
  
  	t.throws( badValue, Error, 'throws an error' );
  	t.end();
  
  	function badValue() {
  		list.insert( n, 'bop' );
  	}
  });
  
  tape( 'the constructor returns a linked list instance which has an `iterator` method which returns an iterator protocol-compliant object', function test( t ) {
  	var list;
  	var it;
  	var v;
  	var i;
  
  	list = new LinkedList();
  	list.push( 'foo' );
  	list.push( 'bar' );
  	list.push( 'beep' );
  	list.push( 'boop' );
  
  	it = list.iterator();
  	t.strictEqual( it.next.length, 0, 'has zero arity' );
  
  	for ( i = 0; i < list.length; i++ ) {
  		v = it.next();
  		t.strictEqual( typeof v.value, 'string', 'returns a string' );
  		t.strictEqual( typeof v.done, 'boolean', 'returns a boolean' );
  	}
  	t.end();
  });
  
  tape( 'a linked list instance iterator allows for iterating over list elements (list snapshot)', function test( t ) {
  	var list;
  	var len;
  	var it;
  	var v;
  	var i;
  
  	list = new LinkedList();
  	list.push( 'foo' );
  	list.push( 'bar' );
  	list.push( 'beep' );
  	list.push( 'boop' );
  
  	len = list.length;
  	it = list.iterator();
  	for ( i = 0; i < len; i++ ) {
  		v = it.next();
  		t.strictEqual( v.value, list.shift(), 'returns expected value' );
  	}
  
  	v = it.next();
  	t.strictEqual( v.value, void 0, 'returns expected value' );
  	t.strictEqual( v.done, true, 'returns expected value' );
  
  	t.end();
  });
  
  tape( 'a linked list instance iterator has a `return` method for closing an iterator (no argument)', function test( t ) {
  	var list;
  	var it;
  	var v;
  
  	list = new LinkedList();
  	list.push( 'foo' );
  	list.push( 'bar' );
  	list.push( 'beep' );
  	list.push( 'boop' );
  
  	it = list.iterator();
  
  	v = it.next();
  	t.strictEqual( v.value, 'foo', 'returns expected value' );
  	t.strictEqual( v.done, false, 'returns expected value' );
  
  	v = it.next();
  	t.strictEqual( v.value, 'bar', 'returns expected value' );
  	t.strictEqual( v.done, false, 'returns expected value' );
  
  	v = it.return();
  	t.strictEqual( v.value, void 0, 'returns expected value' );
  	t.strictEqual( v.done, true, 'returns expected value' );
  
  	v = it.next();
  	t.strictEqual( v.value, void 0, 'returns expected value' );
  	t.strictEqual( v.done, true, 'returns expected value' );
  
  	v = it.next();
  	t.strictEqual( v.value, void 0, 'returns expected value' );
  	t.strictEqual( v.done, true, 'returns expected value' );
  
  	v = it.next();
  	t.strictEqual( v.value, void 0, 'returns expected value' );
  	t.strictEqual( v.done, true, 'returns expected value' );
  
  	v = it.next();
  	t.strictEqual( v.value, void 0, 'returns expected value' );
  	t.strictEqual( v.done, true, 'returns expected value' );
  
  	t.end();
  });
  
  tape( 'a linked list instance iterator has a `return` method for closing an iterator (argument)', function test( t ) {
  	var list;
  	var it;
  	var v;
  
  	list = new LinkedList();
  	list.push( 'foo' );
  	list.push( 'bar' );
  	list.push( 'beep' );
  	list.push( 'boop' );
  
  	it = list.iterator();
  
  	v = it.next();
  	t.strictEqual( v.value, 'foo', 'returns expected value' );
  	t.strictEqual( v.done, false, 'returns expected value' );
  
  	v = it.next();
  	t.strictEqual( v.value, 'bar', 'returns expected value' );
  	t.strictEqual( v.done, false, 'returns expected value' );
  
  	v = it.return( 'finished' );
  	t.strictEqual( v.value, 'finished', 'returns expected value' );
  	t.strictEqual( v.done, true, 'returns expected value' );
  
  	v = it.next();
  	t.strictEqual( v.value, void 0, 'returns expected value' );
  	t.strictEqual( v.done, true, 'returns expected value' );
  
  	t.end();
  });
  
  tape( 'if an environment supports `Symbol.iterator`, a list instance iterator is iterable', function test( t ) {
  	var LinkedList;
  	var list;
  	var it1;
  	var it2;
  	var i;
  
  	LinkedList = proxyquire( './../lib/main.js', {
  		'@stdlib/symbol-iterator': '__ITERATOR_SYMBOL__'
  	});
  
  	list = new LinkedList();
  	list.push( 'foo' );
  	list.push( 'bar' );
  	list.push( 'beep' );
  	list.push( 'boop' );
  
  	it1 = list.iterator();
  	t.strictEqual( typeof it1[ '__ITERATOR_SYMBOL__' ], 'function', 'has method' );
  	t.strictEqual( it1[ '__ITERATOR_SYMBOL__' ].length, 0, 'has zero arity' );
  
  	it2 = it1[ '__ITERATOR_SYMBOL__' ]();
  	t.strictEqual( typeof it2, 'object', 'returns an object' );
  	t.strictEqual( typeof it2.next, 'function', 'has `next` method' );
  	t.strictEqual( typeof it2.return, 'function', 'has `return` method' );
  
  	for ( i = 0; i < 100; i++ ) {
  		t.strictEqual( it2.next().value, it1.next().value, 'returns expected value' );
  	}
  	t.end();
  });
  
  tape( 'if an environment does not support `Symbol.iterator`, a linked list instance iterator is not "iterable"', function test( t ) {
  	var LinkedList;
  	var list;
  	var it;
  
  	LinkedList = proxyquire( './../lib/main.js', {
  		'@stdlib/symbol-iterator': false
  	});
  
  	list = new LinkedList();
  	list.push( 'foo' );
  	list.push( 'bar' );
  	list.push( 'beep' );
  	list.push( 'boop' );
  
  	it = list.iterator();
  	t.strictEqual( it[ iteratorSymbol ], void 0, 'does not have property' );
  
  	t.end();
  });
  
  tape( 'the constructor returns a linked list instance which has a `last` method for returning the last list node', function test( t ) {
  	var list;
  
  	list = new LinkedList();
  	t.strictEqual( list.last(), void 0, 'returns expected value' );
  
  	list.push( 'foo' );
  	t.strictEqual( list.last().value, 'foo', 'returns expected value' );
  
  	list.push( 'bar' );
  	t.strictEqual( list.last().value, 'bar', 'returns expected value' );
  
  	list.pop();
  	t.strictEqual( list.last().value, 'foo', 'returns expected value' );
  
  	list.pop();
  	t.strictEqual( list.last(), void 0, 'returns expected value' );
  
  	t.end();
  });
  
  tape( 'the constructor returns a linked list instance which has a `length` property which returns the number of elements in the list', function test( t ) {
  	var list;
  
  	list = new LinkedList();
  	t.strictEqual( list.length, 0, 'returns expected value' );
  
  	list.push( 'foo' );
  	t.strictEqual( list.length, 1, 'returns expected value' );
  
  	list.push( 'bar' );
  	t.strictEqual( list.length, 2, 'returns expected value' );
  
  	list.pop();
  	t.strictEqual( list.length, 1, 'returns expected value' );
  
  	list.pop();
  	t.strictEqual( list.length, 0, 'returns expected value' );
  
  	list.push( 'foo' );
  	t.strictEqual( list.length, 1, 'returns expected value' );
  
  	list.pop();
  	t.strictEqual( list.length, 0, 'returns expected value' );
  
  	list.push( 'foo' );
  	t.strictEqual( list.length, 1, 'returns expected value' );
  
  	list.push( 'bar' );
  	t.strictEqual( list.length, 2, 'returns expected value' );
  
  	list.pop();
  	t.strictEqual( list.length, 1, 'returns expected value' );
  
  	list.pop();
  	t.strictEqual( list.length, 0, 'returns expected value' );
  
  	t.end();
  });
  
  tape( 'the constructor returns a linked list instance which has a `pop` method for removing the last value from the list', function test( t ) {
  	var list;
  
  	list = new LinkedList();
  	t.strictEqual( list.pop(), void 0, 'returns expected value' );
  	t.strictEqual( list.pop(), void 0, 'returns expected value' );
  	t.strictEqual( list.pop(), void 0, 'returns expected value' );
  
  	list.push( 'foo' );
  	t.strictEqual( list.length, 1, 'returns expected value' );
  	t.strictEqual( list.pop(), 'foo', 'returns expected value' );
  	t.strictEqual( list.length, 0, 'returns expected value' );
  
  	list.push( 'bar' );
  	t.strictEqual( list.length, 1, 'returns expected value' );
  	t.strictEqual( list.pop(), 'bar', 'returns expected value' );
  	t.strictEqual( list.length, 0, 'returns expected value' );
  
  	list.pop();
  	t.strictEqual( list.pop(), void 0, 'returns expected value' );
  	t.strictEqual( list.pop(), void 0, 'returns expected value' );
  	t.strictEqual( list.pop(), void 0, 'returns expected value' );
  
  	t.end();
  });
  
  tape( 'the constructor returns a list instance which has a `push` method for adding an element to the end of the list', function test( t ) {
  	var list;
  	var v;
  
  	list = new LinkedList();
  
  	list.push( 'foo' );
  	t.strictEqual( list.length, 1, 'returns expected value' );
  
  	list.push( 'bar' );
  	t.strictEqual( list.length, 2, 'returns expected value' );
  
  	v = list.pop();
  	t.strictEqual( v, 'bar', 'returns expected value' );
  
  	v = list.pop();
  	t.strictEqual( v, 'foo', 'returns expected value' );
  
  	// Supports chaining:
  	list.push( 'foo' ).push( 'bar' ).push( 'beep' ).push( 'boop' );
  	t.strictEqual( list.length, 4, 'returns expected value' );
  
  	t.end();
  });
  
  tape( 'the constructor returns a list instance which has a `remove` method for removing a node from the list', function test( t ) {
  	var list;
  	var n;
  	var v;
  
  	list = new LinkedList();
  
  	list.push( 'foo' );
  	t.strictEqual( list.length, 1, 'returns expected value' );
  
  	n = list.first();
  	v = list.remove( n );
  	t.strictEqual( list.length, 0, 'returns expected value' );
  	t.strictEqual( v, 'foo', 'returns expected value' );
  
  	list.push( 'foo' );
  	list.push( 'bar' );
  	list.push( 'beep' );
  	list.push( 'boop' );
  	t.strictEqual( list.length, 4, 'returns expected value' );
  
  	n = list.first().next;
  	v = list.remove( n );
  	t.strictEqual( list.length, 3, 'returns expected value' );
  	t.strictEqual( v, 'bar', 'returns expected value' );
  
  	n = list.last();
  	v = list.remove( n );
  	t.strictEqual( list.length, 2, 'returns expected value' );
  	t.strictEqual( v, 'boop', 'returns expected value' );
  
  	t.end();
  });
  
  tape( 'the constructor returns a list instance which has a `remove` method which throws an error if provided a node which is not in the list', function test( t ) {
  	var list;
  	var n;
  
  	list = new LinkedList();
  
  	list.push( 'foo' );
  	list.push( 'bar' );
  	list.push( 'beep' );
  	list.push( 'boop' );
  
  	n = list.last();
  	list.pop();
  
  	t.throws( badValue, Error, 'throws an error' );
  	t.end();
  
  	function badValue() {
  		list.remove( n );
  	}
  });
  
  tape( 'the constructor returns a linked list instance which has a `shift` method for removing the first value from the list', function test( t ) {
  	var list;
  
  	list = new LinkedList();
  	t.strictEqual( list.shift(), void 0, 'returns expected value' );
  	t.strictEqual( list.shift(), void 0, 'returns expected value' );
  	t.strictEqual( list.shift(), void 0, 'returns expected value' );
  
  	list.push( 'foo' );
  	t.strictEqual( list.length, 1, 'returns expected value' );
  	t.strictEqual( list.shift(), 'foo', 'returns expected value' );
  	t.strictEqual( list.length, 0, 'returns expected value' );
  
  	list.push( 'bar' );
  	t.strictEqual( list.length, 1, 'returns expected value' );
  	t.strictEqual( list.shift(), 'bar', 'returns expected value' );
  	t.strictEqual( list.length, 0, 'returns expected value' );
  
  	list.shift();
  	t.strictEqual( list.shift(), void 0, 'returns expected value' );
  	t.strictEqual( list.shift(), void 0, 'returns expected value' );
  	t.strictEqual( list.shift(), void 0, 'returns expected value' );
  
  	t.end();
  });
  
  tape( 'the constructor returns a linked list instance which has a `toArray` method for returning a list of list elements', function test( t ) {
  	var list;
  
  	list = new LinkedList();
  
  	t.deepEqual( list.toArray(), [], 'returns expected value' );
  
  	list.push( 'foo' );
  	list.push( 'bar' );
  	list.push( 'beep' );
  	list.push( 'boop' );
  
  	t.deepEqual( list.toArray(), [ 'foo', 'bar', 'beep', 'boop' ], 'returns expected value' );
  
  	list.clear();
  
  	t.deepEqual( list.toArray(), [], 'returns expected value' );
  
  	list.push( 'foo' );
  	t.deepEqual( list.toArray(), [ 'foo' ], 'returns expected value' );
  
  	t.end();
  });
  
  tape( 'the constructor returns a linked list instance which has a `toJSON` method for serializing a list as JSON', function test( t ) {
  	var expected;
  	var list;
  
  	list = new LinkedList();
  
  	expected = {
  		'type': 'linked-list',
  		'data': []
  	};
  	t.deepEqual( list.toJSON(), expected, 'returns expected value' );
  
  	list.push( 'foo' );
  	list.push( 'bar' );
  	list.push( 'beep' );
  	list.push( 'boop' );
  
  	expected = {
  		'type': 'linked-list',
  		'data': [ 'foo', 'bar', 'beep', 'boop' ]
  	};
  	t.deepEqual( list.toJSON(), expected, 'returns expected value' );
  
  	list.clear();
  
  	expected = {
  		'type': 'linked-list',
  		'data': []
  	};
  	t.deepEqual( list.toJSON(), expected, 'returns expected value' );
  
  	list.push( 'foo' );
  
  	expected = {
  		'type': 'linked-list',
  		'data': [ 'foo' ]
  	};
  	t.deepEqual( list.toJSON(), expected, 'returns expected value' );
  
  	t.end();
  });
  
  tape( 'the constructor returns a list instance which has an `unshift` method for adding an element to the beginning of the list', function test( t ) {
  	var list;
  	var v;
  
  	list = new LinkedList();
  
  	list.unshift( 'foo' );
  	t.strictEqual( list.length, 1, 'returns expected value' );
  
  	list.unshift( 'bar' );
  	t.strictEqual( list.length, 2, 'returns expected value' );
  
  	v = list.pop();
  	t.strictEqual( v, 'foo', 'returns expected value' );
  
  	v = list.pop();
  	t.strictEqual( v, 'bar', 'returns expected value' );
  
  	// Supports chaining:
  	list.unshift( 'foo' ).unshift( 'bar' ).unshift( 'beep' ).unshift( 'boop' );
  	t.strictEqual( list.length, 4, 'returns expected value' );
  
  	t.end();
  });
  