loadjs/test/vendor/chai-4.1.2.js

Tiny async loader for modern browsers

(function(f){if(typeof exports==="object"&&typeof module!=="undefined"){module.exports=f()}else if(typeof define==="function"&&define.amd){define([],f)}else{var g;if(typeof window!=="undefined"){g=window}else if(typeof global!=="undefined"){g=global}else if(typeof self!=="undefined"){g=self}else{g=this}g.chai = f()}})(function(){var define,module,exports;return (function e(t,n,r){function s(o,u){if(!n[o]){if(!t[o]){var a=typeof require=="function"&&require;if(!u&&a)return a(o,!0);if(i)return i(o,!0);var f=new Error("Cannot find module '"+o+"'");throw f.code="MODULE_NOT_FOUND",f}var l=n[o]={exports:{}};t[o][0].call(l.exports,function(e){var n=t[o][1][e];return s(n?n:e)},l,l.exports,e,t,n,r)}return n[o].exports}var i=typeof require=="function"&&require;for(var o=0;o<r.length;o++)s(r[o]);return s})({1:[function(require,module,exports){
module.exports = require('./lib/chai');

},{"./lib/chai":2}],2:[function(require,module,exports){
/*!
 * chai
 * Copyright(c) 2011-2014 Jake Luer <jake@alogicalparadox.com>
 * MIT Licensed
 */

var used = [];

/*!
 * Chai version
 */

exports.version = '4.1.2';

/*!
 * Assertion Error
 */

exports.AssertionError = require('assertion-error');

/*!
 * Utils for plugins (not exported)
 */

var util = require('./chai/utils');

/**
 * # .use(function)
 *
 * Provides a way to extend the internals of Chai.
 *
 * @param {Function}
 * @returns {this} for chaining
 * @api public
 */

exports.use = function (fn) {
  if (!~used.indexOf(fn)) {
    fn(exports, util);
    used.push(fn);
  }

  return exports;
};

/*!
 * Utility Functions
 */

exports.util = util;

/*!
 * Configuration
 */

var config = require('./chai/config');
exports.config = config;

/*!
 * Primary `Assertion` prototype
 */

var assertion = require('./chai/assertion');
exports.use(assertion);

/*!
 * Core Assertions
 */

var core = require('./chai/core/assertions');
exports.use(core);

/*!
 * Expect interface
 */

var expect = require('./chai/interface/expect');
exports.use(expect);

/*!
 * Should interface
 */

var should = require('./chai/interface/should');
exports.use(should);

/*!
 * Assert interface
 */

var assert = require('./chai/interface/assert');
exports.use(assert);

},{"./chai/assertion":3,"./chai/config":4,"./chai/core/assertions":5,"./chai/interface/assert":6,"./chai/interface/expect":7,"./chai/interface/should":8,"./chai/utils":22,"assertion-error":33}],3:[function(require,module,exports){
/*!
 * chai
 * http://chaijs.com
 * Copyright(c) 2011-2014 Jake Luer <jake@alogicalparadox.com>
 * MIT Licensed
 */

var config = require('./config');

module.exports = function (_chai, util) {
  /*!
   * Module dependencies.
   */

  var AssertionError = _chai.AssertionError
    , flag = util.flag;

  /*!
   * Module export.
   */

  _chai.Assertion = Assertion;

  /*!
   * Assertion Constructor
   *
   * Creates object for chaining.
   *
   * `Assertion` objects contain metadata in the form of flags. Three flags can
   * be assigned during instantiation by passing arguments to this constructor:
   *
   * - `object`: This flag contains the target of the assertion. For example, in
   *   the assertion `expect(numKittens).to.equal(7);`, the `object` flag will
   *   contain `numKittens` so that the `equal` assertion can reference it when
   *   needed.
   *
   * - `message`: This flag contains an optional custom error message to be
   *   prepended to the error message that's generated by the assertion when it
   *   fails.
   *
   * - `ssfi`: This flag stands for "start stack function indicator". It
   *   contains a function reference that serves as the starting point for
   *   removing frames from the stack trace of the error that's created by the
   *   assertion when it fails. The goal is to provide a cleaner stack trace to
   *   end users by removing Chai's internal functions. Note that it only works
   *   in environments that support `Error.captureStackTrace`, and only when
   *   `Chai.config.includeStack` hasn't been set to `false`.
   *
   * - `lockSsfi`: This flag controls whether or not the given `ssfi` flag
   *   should retain its current value, even as assertions are chained off of
   *   this object. This is usually set to `true` when creating a new assertion
   *   from within another assertion. It's also temporarily set to `true` before
   *   an overwritten assertion gets called by the overwriting assertion.
   *
   * @param {Mixed} obj target of the assertion
   * @param {String} msg (optional) custom error message
   * @param {Function} ssfi (optional) starting point for removing stack frames
   * @param {Boolean} lockSsfi (optional) whether or not the ssfi flag is locked
   * @api private
   */

  function Assertion (obj, msg, ssfi, lockSsfi) {
    flag(this, 'ssfi', ssfi || Assertion);
    flag(this, 'lockSsfi', lockSsfi);
    flag(this, 'object', obj);
    flag(this, 'message', msg);

    return util.proxify(this);
  }

  Object.defineProperty(Assertion, 'includeStack', {
    get: function() {
      console.warn('Assertion.includeStack is deprecated, use chai.config.includeStack instead.');
      return config.includeStack;
    },
    set: function(value) {
      console.warn('Assertion.includeStack is deprecated, use chai.config.includeStack instead.');
      config.includeStack = value;
    }
  });

  Object.defineProperty(Assertion, 'showDiff', {
    get: function() {
      console.warn('Assertion.showDiff is deprecated, use chai.config.showDiff instead.');
      return config.showDiff;
    },
    set: function(value) {
      console.warn('Assertion.showDiff is deprecated, use chai.config.showDiff instead.');
      config.showDiff = value;
    }
  });

  Assertion.addProperty = function (name, fn) {
    util.addProperty(this.prototype, name, fn);
  };

  Assertion.addMethod = function (name, fn) {
    util.addMethod(this.prototype, name, fn);
  };

  Assertion.addChainableMethod = function (name, fn, chainingBehavior) {
    util.addChainableMethod(this.prototype, name, fn, chainingBehavior);
  };

  Assertion.overwriteProperty = function (name, fn) {
    util.overwriteProperty(this.prototype, name, fn);
  };

  Assertion.overwriteMethod = function (name, fn) {
    util.overwriteMethod(this.prototype, name, fn);
  };

  Assertion.overwriteChainableMethod = function (name, fn, chainingBehavior) {
    util.overwriteChainableMethod(this.prototype, name, fn, chainingBehavior);
  };

  /**
   * ### .assert(expression, message, negateMessage, expected, actual, showDiff)
   *
   * Executes an expression and check expectations. Throws AssertionError for reporting if test doesn't pass.
   *
   * @name assert
   * @param {Philosophical} expression to be tested
   * @param {String|Function} message or function that returns message to display if expression fails
   * @param {String|Function} negatedMessage or function that returns negatedMessage to display if negated expression fails
   * @param {Mixed} expected value (remember to check for negation)
   * @param {Mixed} actual (optional) will default to `this.obj`
   * @param {Boolean} showDiff (optional) when set to `true`, assert will display a diff in addition to the message if expression fails
   * @api private
   */

  Assertion.prototype.assert = function (expr, msg, negateMsg, expected, _actual, showDiff) {
    var ok = util.test(this, arguments);
    if (false !== showDiff) showDiff = true;
    if (undefined === expected && undefined === _actual) showDiff = false;
    if (true !== config.showDiff) showDiff = false;

    if (!ok) {
      msg = util.getMessage(this, arguments);
      var actual = util.getActual(this, arguments);
      throw new AssertionError(msg, {
          actual: actual
        , expected: expected
        , showDiff: showDiff
      }, (config.includeStack) ? this.assert : flag(this, 'ssfi'));
    }
  };

  /*!
   * ### ._obj
   *
   * Quick reference to stored `actual` value for plugin developers.
   *
   * @api private
   */

  Object.defineProperty(Assertion.prototype, '_obj',
    { get: function () {
        return flag(this, 'object');
      }
    , set: function (val) {
        flag(this, 'object', val);
      }
  });
};

},{"./config":4}],4:[function(require,module,exports){
module.exports = {

  /**
   * ### config.includeStack
   *
   * User configurable property, influences whether stack trace
   * is included in Assertion error message. Default of false
   * suppresses stack trace in the error message.
   *
   *     chai.config.includeStack = true;  // enable stack on error
   *
   * @param {Boolean}
   * @api public
   */

  includeStack: false,

  /**
   * ### config.showDiff
   *
   * User configurable property, influences whether or not
   * the `showDiff` flag should be included in the thrown
   * AssertionErrors. `false` will always be `false`; `true`
   * will be true when the assertion has requested a diff
   * be shown.
   *
   * @param {Boolean}
   * @api public
   */

  showDiff: true,

  /**
   * ### config.truncateThreshold
   *
   * User configurable property, sets length threshold for actual and
   * expected values in assertion errors. If this threshold is exceeded, for
   * example for large data structures, the value is replaced with something
   * like `[ Array(3) ]` or `{ Object (prop1, prop2) }`.
   *
   * Set it to zero if you want to disable truncating altogether.
   *
   * This is especially userful when doing assertions on arrays: having this
   * set to a reasonable large value makes the failure messages readily
   * inspectable.
   *
   *     chai.config.truncateThreshold = 0;  // disable truncating
   *
   * @param {Number}
   * @api public
   */

  truncateThreshold: 40,

  /**
   * ### config.useProxy
   *
   * User configurable property, defines if chai will use a Proxy to throw
   * an error when a non-existent property is read, which protects users
   * from typos when using property-based assertions.
   *
   * Set it to false if you want to disable this feature.
   *
   *     chai.config.useProxy = false;  // disable use of Proxy
   *
   * This feature is automatically disabled regardless of this config value
   * in environments that don't support proxies.
   *
   * @param {Boolean}
   * @api public
   */

  useProxy: true,

  /**
   * ### config.proxyExcludedKeys
   *
   * User configurable property, defines which properties should be ignored
   * instead of throwing an error if they do not exist on the assertion.
   * This is only applied if the environment Chai is running in supports proxies and
   * if the `useProxy` configuration setting is enabled.
   * By default, `then` and `inspect` will not throw an error if they do not exist on the
   * assertion object because the `.inspect` property is read by `util.inspect` (for example, when
   * using `console.log` on the assertion object) and `.then` is necessary for promise type-checking.
   *
   *     // By default these keys will not throw an error if they do not exist on the assertion object
   *     chai.config.proxyExcludedKeys = ['then', 'inspect'];
   *
   * @param {Array}
   * @api public
   */

  proxyExcludedKeys: ['then', 'inspect', 'toJSON']
};

},{}],5:[function(require,module,exports){
/*!
 * chai
 * http://chaijs.com
 * Copyright(c) 2011-2014 Jake Luer <jake@alogicalparadox.com>
 * MIT Licensed
 */

module.exports = function (chai, _) {
  var Assertion = chai.Assertion
    , AssertionError = chai.AssertionError
    , flag = _.flag;

  /**
   * ### Language Chains
   *
   * The following are provided as chainable getters to improve the readability
   * of your assertions.
   *
   * **Chains**
   *
   * - to
   * - be
   * - been
   * - is
   * - that
   * - which
   * - and
   * - has
   * - have
   * - with
   * - at
   * - of
   * - same
   * - but
   * - does
   *
   * @name language chains
   * @namespace BDD
   * @api public
   */

  [ 'to', 'be', 'been'
  , 'is', 'and', 'has', 'have'
  , 'with', 'that', 'which', 'at'
  , 'of', 'same', 'but', 'does' ].forEach(function (chain) {
    Assertion.addProperty(chain);
  });

  /**
   * ### .not
   *
   * Negates all assertions that follow in the chain.
   *
   *     expect(function () {}).to.not.throw();
   *     expect({a: 1}).to.not.have.property('b');
   *     expect([1, 2]).to.be.an('array').that.does.not.include(3);
   *
   * Just because you can negate any assertion with `.not` doesn't mean you
   * should. With great power comes great responsibility. It's often best to
   * assert that the one expected output was produced, rather than asserting
   * that one of countless unexpected outputs wasn't produced. See individual
   * assertions for specific guidance.
   *
   *     expect(2).to.equal(2); // Recommended
   *     expect(2).to.not.equal(1); // Not recommended
   *
   * @name not
   * @namespace BDD
   * @api public
   */

  Assertion.addProperty('not', function () {
    flag(this, 'negate', true);
  });

  /**
   * ### .deep
   *
   * Causes all `.equal`, `.include`, `.members`, `.keys`, and `.property`
   * assertions that follow in the chain to use deep equality instead of strict
   * (`===`) equality. See the `deep-eql` project page for info on the deep
   * equality algorithm: https://github.com/chaijs/deep-eql.
   *
   *     // Target object deeply (but not strictly) equals `{a: 1}`
   *     expect({a: 1}).to.deep.equal({a: 1});
   *     expect({a: 1}).to.not.equal({a: 1});
   *
   *     // Target array deeply (but not strictly) includes `{a: 1}`
   *     expect([{a: 1}]).to.deep.include({a: 1});
   *     expect([{a: 1}]).to.not.include({a: 1});
   *
   *     // Target object deeply (but not strictly) includes `x: {a: 1}`
   *     expect({x: {a: 1}}).to.deep.include({x: {a: 1}});
   *     expect({x: {a: 1}}).to.not.include({x: {a: 1}});
   *
   *     // Target array deeply (but not strictly) has member `{a: 1}`
   *     expect([{a: 1}]).to.have.deep.members([{a: 1}]);
   *     expect([{a: 1}]).to.not.have.members([{a: 1}]);
   *
   *     // Target set deeply (but not strictly) has key `{a: 1}`
   *     expect(new Set([{a: 1}])).to.have.deep.keys([{a: 1}]);
   *     expect(new Set([{a: 1}])).to.not.have.keys([{a: 1}]);
   *
   *     // Target object deeply (but not strictly) has property `x: {a: 1}`
   *     expect({x: {a: 1}}).to.have.deep.property('x', {a: 1});
   *     expect({x: {a: 1}}).to.not.have.property('x', {a: 1});
   *
   * @name deep
   * @namespace BDD
   * @api public
   */

  Assertion.addProperty('deep', function () {
    flag(this, 'deep', true);
  });

  /**
   * ### .nested
   *
   * Enables dot- and bracket-notation in all `.property` and `.include`
   * assertions that follow in the chain.
   *
   *     expect({a: {b: ['x', 'y']}}).to.have.nested.property('a.b[1]');
   *     expect({a: {b: ['x', 'y']}}).to.nested.include({'a.b[1]': 'y'});
   *
   * If `.` or `[]` are part of an actual property name, they can be escaped by
   * adding two backslashes before them.
   *
   *     expect({'.a': {'[b]': 'x'}}).to.have.nested.property('\\.a.\\[b\\]');
   *     expect({'.a': {'[b]': 'x'}}).to.nested.include({'\\.a.\\[b\\]': 'x'});
   *
   * `.nested` cannot be combined with `.own`.
   *
   * @name nested
   * @namespace BDD
   * @api public
   */

  Assertion.addProperty('nested', function () {
    flag(this, 'nested', true);
  });

  /**
   * ### .own
   *
   * Causes all `.property` and `.include` assertions that follow in the chain
   * to ignore inherited properties.
   *
   *     Object.prototype.b = 2;
   *
   *     expect({a: 1}).to.have.own.property('a');
   *     expect({a: 1}).to.have.property('b').but.not.own.property('b'); 
   *
   *     expect({a: 1}).to.own.include({a: 1});
   *     expect({a: 1}).to.include({b: 2}).but.not.own.include({b: 2});
   *
   * `.own` cannot be combined with `.nested`.
   *
   * @name own
   * @namespace BDD
   * @api public
   */

  Assertion.addProperty('own', function () {
    flag(this, 'own', true);
  });

  /**
   * ### .ordered
   *
   * Causes all `.members` assertions that follow in the chain to require that
   * members be in the same order.
   *
   *     expect([1, 2]).to.have.ordered.members([1, 2])
   *       .but.not.have.ordered.members([2, 1]);
   *
   * When `.include` and `.ordered` are combined, the ordering begins at the
   * start of both arrays.
   *
   *     expect([1, 2, 3]).to.include.ordered.members([1, 2])
   *       .but.not.include.ordered.members([2, 3]);
   *
   * @name ordered
   * @namespace BDD
   * @api public
   */

  Assertion.addProperty('ordered', function () {
    flag(this, 'ordered', true);
  });

  /**
   * ### .any
   *
   * Causes all `.keys` assertions that follow in the chain to only require that
   * the target have at least one of the given keys. This is the opposite of
   * `.all`, which requires that the target have all of the given keys.
   *
   *     expect({a: 1, b: 2}).to.not.have.any.keys('c', 'd');
   *
   * See the `.keys` doc for guidance on when to use `.any` or `.all`.
   *
   * @name any
   * @namespace BDD
   * @api public
   */

  Assertion.addProperty('any', function () {
    flag(this, 'any', true);
    flag(this, 'all', false);
  });


  /**
   * ### .all
   *
   * Causes all `.keys` assertions that follow in the chain to require that the
   * target have all of the given keys. This is the opposite of `.any`, which
   * only requires that the target have at least one of the given keys.
   *
   *     expect({a: 1, b: 2}).to.have.all.keys('a', 'b');
   *
   * Note that `.all` is used by default when neither `.all` nor `.any` are
   * added earlier in the chain. However, it's often best to add `.all` anyway
   * because it improves readability.
   *
   * See the `.keys` doc for guidance on when to use `.any` or `.all`.
   *
   * @name all
   * @namespace BDD
   * @api public
   */

  Assertion.addProperty('all', function () {
    flag(this, 'all', true);
    flag(this, 'any', false);
  });

  /**
   * ### .a(type[, msg])
   *
   * Asserts that the target's type is equal to the given string `type`. Types
   * are case insensitive. See the `type-detect` project page for info on the
   * type detection algorithm: https://github.com/chaijs/type-detect.
   *
   *     expect('foo').to.be.a('string');
   *     expect({a: 1}).to.be.an('object');
   *     expect(null).to.be.a('null');
   *     expect(undefined).to.be.an('undefined');
   *     expect(new Error).to.be.an('error');
   *     expect(Promise.resolve()).to.be.a('promise');
   *     expect(new Float32Array).to.be.a('float32array');
   *     expect(Symbol()).to.be.a('symbol');
   *
   * `.a` supports objects that have a custom type set via `Symbol.toStringTag`.
   *
   *     var myObj = {
   *       [Symbol.toStringTag]: 'myCustomType'
   *     };
   *
   *     expect(myObj).to.be.a('myCustomType').but.not.an('object');
   *
   * It's often best to use `.a` to check a target's type before making more
   * assertions on the same target. That way, you avoid unexpected behavior from
   * any assertion that does different things based on the target's type.
   *
   *     expect([1, 2, 3]).to.be.an('array').that.includes(2);
   *     expect([]).to.be.an('array').that.is.empty;
   *
   * Add `.not` earlier in the chain to negate `.a`. However, it's often best to
   * assert that the target is the expected type, rather than asserting that it
   * isn't one of many unexpected types.
   *
   *     expect('foo').to.be.a('string'); // Recommended
   *     expect('foo').to.not.be.an('array'); // Not recommended
   *
   * `.a` accepts an optional `msg` argument which is a custom error message to
   * show when the assertion fails. The message can also be given as the second
   * argument to `expect`.
   *
   *     expect(1).to.be.a('string', 'nooo why fail??');
   *     expect(1, 'nooo why fail??').to.be.a('string');
   *
   * `.a` can also be used as a language chain to improve the readability of
   * your assertions. 
   *
   *     expect({b: 2}).to.have.a.property('b');
   *
   * The alias `.an` can be used interchangeably with `.a`.
   *
   * @name a
   * @alias an
   * @param {String} type
   * @param {String} msg _optional_
   * @namespace BDD
   * @api public
   */

  function an (type, msg) {
    if (msg) flag(this, 'message', msg);
    type = type.toLowerCase();
    var obj = flag(this, 'object')
      , article = ~[ 'a', 'e', 'i', 'o', 'u' ].indexOf(type.charAt(0)) ? 'an ' : 'a ';

    this.assert(
        type === _.type(obj).toLowerCase()
      , 'expected #{this} to be ' + article + type
      , 'expected #{this} not to be ' + article + type
    );
  }

  Assertion.addChainableMethod('an', an);
  Assertion.addChainableMethod('a', an);

  /**
   * ### .include(val[, msg])
   *
   * When the target is a string, `.include` asserts that the given string `val`
   * is a substring of the target.
   *
   *     expect('foobar').to.include('foo');
   *
   * When the target is an array, `.include` asserts that the given `val` is a
   * member of the target.
   *
   *     expect([1, 2, 3]).to.include(2);
   *
   * When the target is an object, `.include` asserts that the given object
   * `val`'s properties are a subset of the target's properties.
   *
   *     expect({a: 1, b: 2, c: 3}).to.include({a: 1, b: 2});
   *
   * When the target is a Set or WeakSet, `.include` asserts that the given `val` is a
   * member of the target. SameValueZero equality algorithm is used.
   *
   *     expect(new Set([1, 2])).to.include(2);
   *
   * When the target is a Map, `.include` asserts that the given `val` is one of
   * the values of the target. SameValueZero equality algorithm is used.
   *
   *     expect(new Map([['a', 1], ['b', 2]])).to.include(2);
   *
   * Because `.include` does different things based on the target's type, it's
   * important to check the target's type before using `.include`. See the `.a`
   * doc for info on testing a target's type.
   *
   *     expect([1, 2, 3]).to.be.an('array').that.includes(2);
   *
   * By default, strict (`===`) equality is used to compare array members and
   * object properties. Add `.deep` earlier in the chain to use deep equality
   * instead (WeakSet targets are not supported). See the `deep-eql` project
   * page for info on the deep equality algorithm: https://github.com/chaijs/deep-eql.
   *
   *     // Target array deeply (but not strictly) includes `{a: 1}`
   *     expect([{a: 1}]).to.deep.include({a: 1});
   *     expect([{a: 1}]).to.not.include({a: 1});
   *
   *     // Target object deeply (but not strictly) includes `x: {a: 1}`
   *     expect({x: {a: 1}}).to.deep.include({x: {a: 1}});
   *     expect({x: {a: 1}}).to.not.include({x: {a: 1}});
   *
   * By default, all of the target's properties are searched when working with
   * objects. This includes properties that are inherited and/or non-enumerable.
   * Add `.own` earlier in the chain to exclude the target's inherited
   * properties from the search.
   *
   *     Object.prototype.b = 2;
   *
   *     expect({a: 1}).to.own.include({a: 1});
   *     expect({a: 1}).to.include({b: 2}).but.not.own.include({b: 2});
   *
   * Note that a target object is always only searched for `val`'s own
   * enumerable properties.
   *
   * `.deep` and `.own` can be combined.
   *
   *     expect({a: {b: 2}}).to.deep.own.include({a: {b: 2}});
   *
   * Add `.nested` earlier in the chain to enable dot- and bracket-notation when
   * referencing nested properties.
   *
   *     expect({a: {b: ['x', 'y']}}).to.nested.include({'a.b[1]': 'y'});
   *
   * If `.` or `[]` are part of an actual property name, they can be escaped by
   * adding two backslashes before them.
   *
   *     expect({'.a': {'[b]': 2}}).to.nested.include({'\\.a.\\[b\\]': 2});
   *
   * `.deep` and `.nested` can be combined.
   *
   *     expect({a: {b: [{c: 3}]}}).to.deep.nested.include({'a.b[0]': {c: 3}});
   *
   * `.own` and `.nested` cannot be combined.
   *
   * Add `.not` earlier in the chain to negate `.include`.
   *
   *     expect('foobar').to.not.include('taco');
   *     expect([1, 2, 3]).to.not.include(4);
   * 
   * However, it's dangerous to negate `.include` when the target is an object.
   * The problem is that it creates uncertain expectations by asserting that the
   * target object doesn't have all of `val`'s key/value pairs but may or may
   * not have some of them. It's often best to identify the exact output that's
   * expected, and then write an assertion that only accepts that exact output.
   *
   * When the target object isn't even expected to have `val`'s keys, it's
   * often best to assert exactly that.
   *
   *     expect({c: 3}).to.not.have.any.keys('a', 'b'); // Recommended
   *     expect({c: 3}).to.not.include({a: 1, b: 2}); // Not recommended
   *
   * When the target object is expected to have `val`'s keys, it's often best to
   * assert that each of the properties has its expected value, rather than
   * asserting that each property doesn't have one of many unexpected values.
   *
   *     expect({a: 3, b: 4}).to.include({a: 3, b: 4}); // Recommended
   *     expect({a: 3, b: 4}).to.not.include({a: 1, b: 2}); // Not recommended
   *
   * `.include` accepts an optional `msg` argument which is a custom error
   * message to show when the assertion fails. The message can also be given as
   * the second argument to `expect`.
   *
   *     expect([1, 2, 3]).to.include(4, 'nooo why fail??');
   *     expect([1, 2, 3], 'nooo why fail??').to.include(4);
   *
   * `.include` can also be used as a language chain, causing all `.members` and
   * `.keys` assertions that follow in the chain to require the target to be a
   * superset of the expected set, rather than an identical set. Note that
   * `.members` ignores duplicates in the subset when `.include` is added.
   *
   *     // Target object's keys are a superset of ['a', 'b'] but not identical
   *     expect({a: 1, b: 2, c: 3}).to.include.all.keys('a', 'b');
   *     expect({a: 1, b: 2, c: 3}).to.not.have.all.keys('a', 'b');
   *
   *     // Target array is a superset of [1, 2] but not identical
   *     expect([1, 2, 3]).to.include.members([1, 2]);
   *     expect([1, 2, 3]).to.not.have.members([1, 2]);
   *
   *     // Duplicates in the subset are ignored
   *     expect([1, 2, 3]).to.include.members([1, 2, 2, 2]);
   *
   * Note that adding `.any` earlier in the chain causes the `.keys` assertion
   * to ignore `.include`.
   *
   *     // Both assertions are identical
   *     expect({a: 1}).to.include.any.keys('a', 'b');
   *     expect({a: 1}).to.have.any.keys('a', 'b');
   *
   * The aliases `.includes`, `.contain`, and `.contains` can be used
   * interchangeably with `.include`.
   *
   * @name include
   * @alias contain
   * @alias includes
   * @alias contains
   * @param {Mixed} val
   * @param {String} msg _optional_
   * @namespace BDD
   * @api public
   */

  function SameValueZero(a, b) {
    return (_.isNaN(a) && _.isNaN(b)) || a === b;
  }

  function includeChainingBehavior () {
    flag(this, 'contains', true);
  }

  function include (val, msg) {
    if (msg) flag(this, 'message', msg);
    
    var obj = flag(this, 'object')
      , objType = _.type(obj).toLowerCase()
      , flagMsg = flag(this, 'message')
      , negate = flag(this, 'negate')
      , ssfi = flag(this, 'ssfi')
      , isDeep = flag(this, 'deep')
      , descriptor = isDeep ? 'deep ' : '';

    flagMsg = flagMsg ? flagMsg + ': ' : '';

    var included = false;

    switch (objType) {
      case 'string':
        included = obj.indexOf(val) !== -1;
        break;

      case 'weakset':
        if (isDeep) {
          throw new AssertionError(
            flagMsg + 'unable to use .deep.include with WeakSet',
            undefined,
            ssfi
          );
        }

        included = obj.has(val);
        break;

      case 'map':
        var isEql = isDeep ? _.eql : SameValueZero;
        obj.forEach(function (item) {
          included = included || isEql(item, val);
        });
        break;

      case 'set':
        if (isDeep) {
          obj.forEach(function (item) {
            included = included || _.eql(item, val);
          });
        } else {
          included = obj.has(val);
        }
        break;

      case 'array':
        if (isDeep) {
          included = obj.some(function (item) {
            return _.eql(item, val);
          })
        } else {
          included = obj.indexOf(val) !== -1;
        }
        break;

      default:
        // This block is for asserting a subset of properties in an object.
        // `_.expectTypes` isn't used here because `.include` should work with
        // objects with a custom `@@toStringTag`.
        if (val !== Object(val)) {
          throw new AssertionError(
            flagMsg + 'object tested must be an array, a map, an object,'
              + ' a set, a string, or a weakset, but ' + objType + ' given',
            undefined,
            ssfi
          );
        }

        var props = Object.keys(val)
          , firstErr = null
          , numErrs = 0;
  
        props.forEach(function (prop) {
          var propAssertion = new Assertion(obj);
          _.transferFlags(this, propAssertion, true);
          flag(propAssertion, 'lockSsfi', true);
  
          if (!negate || props.length === 1) {
            propAssertion.property(prop, val[prop]);
            return;
          }
  
          try {
            propAssertion.property(prop, val[prop]);
          } catch (err) {
            if (!_.checkError.compatibleConstructor(err, AssertionError)) {
              throw err;
            }
            if (firstErr === null) firstErr = err;
            numErrs++;
          }
        }, this);
  
        // When validating .not.include with multiple properties, we only want
        // to throw an assertion error if all of the properties are included,
        // in which case we throw the first property assertion error that we
        // encountered.
        if (negate && props.length > 1 && numErrs === props.length) {
          throw firstErr;
        }
        return;
    }

    // Assert inclusion in collection or substring in a string.
    this.assert(
      included
      , 'expected #{this} to ' + descriptor + 'include ' + _.inspect(val)
      , 'expected #{this} to not ' + descriptor + 'include ' + _.inspect(val));
  }

  Assertion.addChainableMethod('include', include, includeChainingBehavior);
  Assertion.addChainableMethod('contain', include, includeChainingBehavior);
  Assertion.addChainableMethod('contains', include, includeChainingBehavior);
  Assertion.addChainableMethod('includes', include, includeChainingBehavior);

  /**
   * ### .ok
   *
   * Asserts that the target is loosely (`==`) equal to `true`. However, it's
   * often best to assert that the target is strictly (`===`) or deeply equal to
   * its expected value.
   *
   *     expect(1).to.equal(1); // Recommended
   *     expect(1).to.be.ok; // Not recommended
   *
   *     expect(true).to.be.true; // Recommended
   *     expect(true).to.be.ok; // Not recommended
   *
   * Add `.not` earlier in the chain to negate `.ok`.
   *
   *     expect(0).to.equal(0); // Recommended
   *     expect(0).to.not.be.ok; // Not recommended
   *
   *     expect(false).to.be.false; // Recommended
   *     expect(false).to.not.be.ok; // Not recommended
   *
   *     expect(null).to.be.null; // Recommended
   *     expect(null).to.not.be.ok; // Not recommended
   *
   *     expect(undefined).to.be.undefined; // Recommended
   *     expect(undefined).to.not.be.ok; // Not recommended
   *
   * A custom error message can be given as the second argument to `expect`.
   *
   *     expect(false, 'nooo why fail??').to.be.ok;
   *
   * @name ok
   * @namespace BDD
   * @api public
   */

  Assertion.addProperty('ok', function () {
    this.assert(
        flag(this, 'object')
      , 'expected #{this} to be truthy'
      , 'expected #{this} to be falsy');
  });

  /**
   * ### .true
   *
   * Asserts that the target is strictly (`===`) equal to `true`.
   *
   *     expect(true).to.be.true;
   *
   * Add `.not` earlier in the chain to negate `.true`. However, it's often best
   * to assert that the target is equal to its expected value, rather than not
   * equal to `true`.
   *
   *     expect(false).to.be.false; // Recommended
   *     expect(false).to.not.be.true; // Not recommended
   *
   *     expect(1).to.equal(1); // Recommended
   *     expect(1).to.not.be.true; // Not recommended
   *
   * A custom error message can be given as the second argument to `expect`.
   *
   *     expect(false, 'nooo why fail??').to.be.true;
   *
   * @name true
   * @namespace BDD
   * @api public
   */

  Assertion.addProperty('true', function () {
    this.assert(
        true === flag(this, 'object')
      , 'expected #{this} to be true'
      , 'expected #{this} to be false'
      , flag(this, 'negate') ? false : true
    );
  });

  /**
   * ### .false
   *
   * Asserts that the target is strictly (`===`) equal to `false`.
   *
   *     expect(false).to.be.false;
   *
   * Add `.not` earlier in the chain to negate `.false`. However, it's often
   * best to assert that the target is equal to its expected value, rather than
   * not equal to `false`.
   *
   *     expect(true).to.be.true; // Recommended
   *     expect(true).to.not.be.false; // Not recommended
   *
   *     expect(1).to.equal(1); // Recommended
   *     expect(1).to.not.be.false; // Not recommended
   *
   * A custom error message can be given as the second argument to `expect`.
   *
   *     expect(true, 'nooo why fail??').to.be.false;
   *
   * @name false
   * @namespace BDD
   * @api public
   */

  Assertion.addProperty('false', function () {
    this.assert(
        false === flag(this, 'object')
      , 'expected #{this} to be false'
      , 'expected #{this} to be true'
      , flag(this, 'negate') ? true : false
    );
  });

  /**
   * ### .null
   *
   * Asserts that the target is strictly (`===`) equal to `null`.
   *
   *     expect(null).to.be.null;
   *
   * Add `.not` earlier in the chain to negate `.null`. However, it's often best
   * to assert that the target is equal to its expected value, rather than not
   * equal to `null`.
   *
   *     expect(1).to.equal(1); // Recommended
   *     expect(1).to.not.be.null; // Not recommended
   *
   * A custom error message can be given as the second argument to `expect`.
   *
   *     expect(42, 'nooo why fail??').to.be.null;
   *
   * @name null
   * @namespace BDD
   * @api public
   */

  Assertion.addProperty('null', function () {
    this.assert(
        null === flag(this, 'object')
      , 'expected #{this} to be null'
      , 'expected #{this} not to be null'
    );
  });

  /**
   * ### .undefined
   *
   * Asserts that the target is strictly (`===`) equal to `undefined`.
   *
   *     expect(undefined).to.be.undefined;
   *
   * Add `.not` earlier in the chain to negate `.undefined`. However, it's often
   * best to assert that the target is equal to its expected value, rather than
   * not equal to `undefined`.
   *
   *     expect(1).to.equal(1); // Recommended
   *     expect(1).to.not.be.undefined; // Not recommended
   *
   * A custom error message can be given as the second argument to `expect`.
   *
   *     expect(42, 'nooo why fail??').to.be.undefined;
   *
   * @name undefined
   * @namespace BDD
   * @api public
   */

  Assertion.addProperty('undefined', function () {
    this.assert(
        undefined === flag(this, 'object')
      , 'expected #{this} to be undefined'
      , 'expected #{this} not to be undefined'
    );
  });

  /**
   * ### .NaN
   *
   * Asserts that the target is exactly `NaN`.
   *
   *     expect(NaN).to.be.NaN;
   *
   * Add `.not` earlier in the chain to negate `.NaN`. However, it's often best
   * to assert that the target is equal to its expected value, rather than not
   * equal to `NaN`.
   *
   *     expect('foo').to.equal('foo'); // Recommended
   *     expect('foo').to.not.be.NaN; // Not recommended
   *
   * A custom error message can be given as the second argument to `expect`.
   *
   *     expect(42, 'nooo why fail??').to.be.NaN;
   *
   * @name NaN
   * @namespace BDD
   * @api public
   */

  Assertion.addProperty('NaN', function () {
    this.assert(
        _.isNaN(flag(this, 'object'))
        , 'expected #{this} to be NaN'
        , 'expected #{this} not to be NaN'
    );
  });

  /**
   * ### .exist
   *
   * Asserts that the target is not strictly (`===`) equal to either `null` or
   * `undefined`. However, it's often best to assert that the target is equal to
   * its expected value.
   *
   *     expect(1).to.equal(1); // Recommended
   *     expect(1).to.exist; // Not recommended
   *
   *     expect(0).to.equal(0); // Recommended
   *     expect(0).to.exist; // Not recommended
   *
   * Add `.not` earlier in the chain to negate `.exist`.
   *
   *     expect(null).to.be.null; // Recommended
   *     expect(null).to.not.exist; // Not recommended
   *
   *     expect(undefined).to.be.undefined; // Recommended
   *     expect(undefined).to.not.exist; // Not recommended
   *
   * A custom error message can be given as the second argument to `expect`.
   *
   *     expect(null, 'nooo why fail??').to.exist;
   *
   * @name exist
   * @namespace BDD
   * @api public
   */

  Assertion.addProperty('exist', function () {
    var val = flag(this, 'object');
    this.assert(
        val !== null && val !== undefined
      , 'expected #{this} to exist'
      , 'expected #{this} to not exist'
    );
  });

  /**
   * ### .empty
   *
   * When the target is a string or array, `.empty` asserts that the target's
   * `length` property is strictly (`===`) equal to `0`.
   *
   *     expect([]).to.be.empty;
   *     expect('').to.be.empty;
   *
   * When the target is a map or set, `.empty` asserts that the target's `size`
   * property is strictly equal to `0`.
   *
   *     expect(new Set()).to.be.empty;
   *     expect(new Map()).to.be.empty;
   *
   * When the target is a non-function object, `.empty` asserts that the target
   * doesn't have any own enumerable properties. Properties with Symbol-based
   * keys are excluded from the count.
   *
   *     expect({}).to.be.empty;
   *
   * Because `.empty` does different things based on the target's type, it's
   * important to check the target's type before using `.empty`. See the `.a`
   * doc for info on testing a target's type.
   *
   *     expect([]).to.be.an('array').that.is.empty;
   *
   * Add `.not` earlier in the chain to negate `.empty`. However, it's often
   * best to assert that the target contains its expected number of values,
   * rather than asserting that it's not empty.
   *
   *     expect([1, 2, 3]).to.have.lengthOf(3); // Recommended
   *     expect([1, 2, 3]).to.not.be.empty; // Not recommended
   *
   *     expect(new Set([1, 2, 3])).to.have.property('size', 3); // Recommended
   *     expect(new Set([1, 2, 3])).to.not.be.empty; // Not recommended
   *
   *     expect(Object.keys({a: 1})).to.have.lengthOf(1); // Recommended
   *     expect({a: 1}).to.not.be.empty; // Not recommended
   *
   * A custom error message can be given as the second argument to `expect`.
   *
   *     expect([1, 2, 3], 'nooo why fail??').to.be.empty;
   *
   * @name empty
   * @namespace BDD
   * @api public
   */

  Assertion.addProperty('empty', function () {
    var val = flag(this, 'object')
      , ssfi = flag(this, 'ssfi')
      , flagMsg = flag(this, 'message')
      , itemsCount;

    flagMsg = flagMsg ? flagMsg + ': ' : '';

    switch (_.type(val).toLowerCase()) {
      case 'array':
      case 'string':
        itemsCount = val.length;
        break;
      case 'map':
      case 'set':
        itemsCount = val.size;
        break;
      case 'weakmap':
      case 'weakset':
        throw new AssertionError(
          flagMsg + '.empty was passed a weak collection',
          undefined,
          ssfi
        );
      case 'function':
        var msg = flagMsg + '.empty was passed a function ' + _.getName(val);
        throw new AssertionError(msg.trim(), undefined, ssfi);
      default:
        if (val !== Object(val)) {
          throw new AssertionError(
            flagMsg + '.empty was passed non-string primitive ' + _.inspect(val),
            undefined,
            ssfi
          );
        }
        itemsCount = Object.keys(val).length;
    }

    this.assert(
        0 === itemsCount
      , 'expected #{this} to be empty'
      , 'expected #{this} not to be empty'
    );
  });

  /**
   * ### .arguments
   *
   * Asserts that the target is an `arguments` object.
   *
   *     function test () {
   *       expect(arguments).to.be.arguments;
   *     }
   *
   *     test();
   *
   * Add `.not` earlier in the chain to negate `.arguments`. However, it's often
   * best to assert which type the target is expected to be, rather than
   * asserting that its not an `arguments` object.
   *
   *     expect('foo').to.be.a('string'); // Recommended
   *     expect('foo').to.not.be.arguments; // Not recommended
   *
   * A custom error message can be given as the second argument to `expect`.
   *
   *     expect({}, 'nooo why fail??').to.be.arguments;
   *
   * The alias `.Arguments` can be used interchangeably with `.arguments`.
   *
   * @name arguments
   * @alias Arguments
   * @namespace BDD
   * @api public
   */

  function checkArguments () {
    var obj = flag(this, 'object')
      , type = _.type(obj);
    this.assert(
        'Arguments' === type
      , 'expected #{this} to be arguments but got ' + type
      , 'expected #{this} to not be arguments'
    );
  }

  Assertion.addProperty('arguments', checkArguments);
  Assertion.addProperty('Arguments', checkArguments);

  /**
   * ### .equal(val[, msg])
   *
   * Asserts that the target is strictly (`===`) equal to the given `val`.
   *
   *     expect(1).to.equal(1);
   *     expect('foo').to.equal('foo');
   * 
   * Add `.deep` earlier in the chain to use deep equality instead. See the
   * `deep-eql` project page for info on the deep equality algorithm:
   * https://github.com/chaijs/deep-eql.
   *
   *     // Target object deeply (but not strictly) equals `{a: 1}`
   *     expect({a: 1}).to.deep.equal({a: 1});
   *     expect({a: 1}).to.not.equal({a: 1});
   *
   *     // Target array deeply (but not strictly) equals `[1, 2]`
   *     expect([1, 2]).to.deep.equal([1, 2]);
   *     expect([1, 2]).to.not.equal([1, 2]);
   *
   * Add `.not` earlier in the chain to negate `.equal`. However, it's often
   * best to assert that the target is equal to its expected value, rather than
   * not equal to one of countless unexpected values.
   *
   *     expect(1).to.equal(1); // Recommended
   *     expect(1).to.not.equal(2); // Not recommended
   *
   * `.equal` accepts an optional `msg` argument which is a custom error message
   * to show when the assertion fails. The message can also be given as the
   * second argument to `expect`.
   *
   *     expect(1).to.equal(2, 'nooo why fail??');
   *     expect(1, 'nooo why fail??').to.equal(2);
   *
   * The aliases `.equals` and `eq` can be used interchangeably with `.equal`.
   *
   * @name equal
   * @alias equals
   * @alias eq
   * @param {Mixed} val
   * @param {String} msg _optional_
   * @namespace BDD
   * @api public
   */

  function assertEqual (val, msg) {
    if (msg) flag(this, 'message', msg);
    var obj = flag(this, 'object');
    if (flag(this, 'deep')) {
      return this.eql(val);
    } else {
      this.assert(
          val === obj
        , 'expected #{this} to equal #{exp}'
        , 'expected #{this} to not equal #{exp}'
        , val
        , this._obj
        , true
      );
    }
  }

  Assertion.addMethod('equal', assertEqual);
  Assertion.addMethod('equals', assertEqual);
  Assertion.addMethod('eq', assertEqual);

  /**
   * ### .eql(obj[, msg])
   *
   * Asserts that the target is deeply equal to the given `obj`. See the
   * `deep-eql` project page for info on the deep equality algorithm:
   * https://github.com/chaijs/deep-eql.
   *
   *     // Target object is deeply (but not strictly) equal to {a: 1}
   *     expect({a: 1}).to.eql({a: 1}).but.not.equal({a: 1});
   *
   *     // Target array is deeply (but not strictly) equal to [1, 2]
   *     expect([1, 2]).to.eql([1, 2]).but.not.equal([1, 2]);
   *
   * Add `.not` earlier in the chain to negate `.eql`. However, it's often best
   * to assert that the target is deeply equal to its expected value, rather
   * than not deeply equal to one of countless unexpected values.
   *
   *     expect({a: 1}).to.eql({a: 1}); // Recommended
   *     expect({a: 1}).to.not.eql({b: 2}); // Not recommended
   *
   * `.eql` accepts an optional `msg` argument which is a custom error message
   * to show when the assertion fails. The message can also be given as the
   * second argument to `expect`.
   *
   *     expect({a: 1}).to.eql({b: 2}, 'nooo why fail??');
   *     expect({a: 1}, 'nooo why fail??').to.eql({b: 2});
   *
   * The alias `.eqls` can be used interchangeably with `.eql`.
   *
   * The `.deep.equal` assertion is almost identical to `.eql` but with one
   * difference: `.deep.equal` causes deep equality comparisons to also be used
   * for any other assertions that follow in the chain.
   *
   * @name eql
   * @alias eqls
   * @param {Mixed} obj
   * @param {String} msg _optional_
   * @namespace BDD
   * @api public
   */

  function assertEql(obj, msg) {
    if (msg) flag(this, 'message', msg);
    this.assert(
        _.eql(obj, flag(this, 'object'))
      , 'expected #{this} to deeply equal #{exp}'
      , 'expected #{this} to not deeply equal #{exp}'
      , obj
      , this._obj
      , true
    );
  }

  Assertion.addMethod('eql', assertEql);
  Assertion.addMethod('eqls', assertEql);

  /**
   * ### .above(n[, msg])
   *
   * Asserts that the target is a number or a date greater than the given number or date `n` respectively.
   * However, it's often best to assert that the target is equal to its expected
   * value.
   *
   *     expect(2).to.equal(2); // Recommended
   *     expect(2).to.be.above(1); // Not recommended
   *
   * Add `.lengthOf` earlier in the chain to assert that the value of the
   * target's `length` property is greater than the given number `n`.
   *
   *     expect('foo').to.have.lengthOf(3); // Recommended
   *     expect('foo').to.have.lengthOf.above(2); // Not recommended
   *
   *     expect([1, 2, 3]).to.have.lengthOf(3); // Recommended
   *     expect([1, 2, 3]).to.have.lengthOf.above(2); // Not recommended
   *
   * Add `.not` earlier in the chain to negate `.above`.
   *
   *     expect(2).to.equal(2); // Recommended
   *     expect(1).to.not.be.above(2); // Not recommended
   *
   * `.above` accepts an optional `msg` argument which is a custom error message
   * to show when the assertion fails. The message can also be given as the
   * second argument to `expect`.
   *
   *     expect(1).to.be.above(2, 'nooo why fail??');
   *     expect(1, 'nooo why fail??').to.be.above(2);
   *
   * The aliases `.gt` and `.greaterThan` can be used interchangeably with
   * `.above`.
   *
   * @name above
   * @alias gt
   * @alias greaterThan
   * @param {Number} n
   * @param {String} msg _optional_
   * @namespace BDD
   * @api public
   */

  function assertAbove (n, msg) {
    if (msg) flag(this, 'message', msg);
    var obj = flag(this, 'object')
      , doLength = flag(this, 'doLength')
      , flagMsg = flag(this, 'message')
      , msgPrefix = ((flagMsg) ? flagMsg + ': ' : '')
      , ssfi = flag(this, 'ssfi')
      , objType = _.type(obj).toLowerCase()
      , nType = _.type(n).toLowerCase()
      , shouldThrow = true;

    if (doLength) {
      new Assertion(obj, flagMsg, ssfi, true).to.have.property('length');
    }
    
    if (!doLength && (objType === 'date' && nType !== 'date')) {
      errorMessage = msgPrefix + 'the argument to above must be a date';
    } else if (nType !== 'number' && (doLength || objType === 'number')) {
      errorMessage = msgPrefix + 'the argument to above must be a number';
    } else if (!doLength && (objType !== 'date' && objType !== 'number')) {
      var printObj = (objType === 'string') ? "'" + obj + "'" : obj;
      errorMessage = msgPrefix + 'expected ' + printObj + ' to be a number or a date';
    } else {
      shouldThrow = false;
    }

    if (shouldThrow) {
      throw new AssertionError(errorMessage, undefined, ssfi);
    }

    if (doLength) {
      var len = obj.length;
      this.assert(
          len > n
        , 'expected #{this} to have a length above #{exp} but got #{act}'
        , 'expected #{this} to not have a length above #{exp}'
        , n
        , len
      );
    } else {
      this.assert(
          obj > n
        , 'expected #{this} to be above #{exp}'
        , 'expected #{this} to be at most #{exp}'
        , n
      );
    }
  }

  Assertion.addMethod('above', assertAbove);
  Assertion.addMethod('gt', assertAbove);
  Assertion.addMethod('greaterThan', assertAbove);

  /**
   * ### .least(n[, msg])
   *
   * Asserts that the target is a number or a date greater than or equal to the given
   * number or date `n` respectively. However, it's often best to assert that the target is equal to
   * its expected value.
   *
   *     expect(2).to.equal(2); // Recommended
   *     expect(2).to.be.at.least(1); // Not recommended
   *     expect(2).to.be.at.least(2); // Not recommended
   *
   * Add `.lengthOf` earlier in the chain to assert that the value of the
   * target's `length` property is greater than or equal to the given number
   * `n`.
   *
   *     expect('foo').to.have.lengthOf(3); // Recommended
   *     expect('foo').to.have.lengthOf.at.least(2); // Not recommended
   *
   *     expect([1, 2, 3]).to.have.lengthOf(3); // Recommended
   *     expect([1, 2, 3]).to.have.lengthOf.at.least(2); // Not recommended
   *
   * Add `.not` earlier in the chain to n