lodash/test/mixin.js

import assert from 'assert';
import lodashStable from 'lodash';
import { slice, getUnwrappedValue, noop } from './utils.js';
import has from '../has.js';
import mixin from '../mixin.js';
import prototype from '../prototype.js';
import countBy from '../countBy.js';
import filter from '../filter.js';

describe('mixin', function() {
  function reset(wrapper) {
    delete wrapper.a;
    delete wrapper.prototype.a;
    delete wrapper.b;
    delete wrapper.prototype.b;
  }

  function Wrapper(value) {
    if (!(this instanceof Wrapper)) {
      return new Wrapper(value);
    }
    if (has(value, '__wrapped__')) {
      var actions = slice.call(value.__actions__),
          chain = value.__chain__;

      value = value.__wrapped__;
    }
    this.__wrapped__ = value;
    this.__actions__ = actions || [];
    this.__chain__ = chain || false;
  }

  Wrapper.prototype.value = function() {
    return getUnwrappedValue(this);
  };

  var array = ['a'],
      source = { 'a': function(array) { return array[0]; }, 'b': 'B' };

  it('should mixin `source` methods into lodash', function() {
    mixin(source);

    assert.strictEqual(_.a(array), 'a');
    assert.strictEqual(_(array).a().value(), 'a');
    assert.notOk('b' in _);
    assert.notOk('b' in prototype);

    reset(_);
  });

  it('should mixin chaining methods by reference', function() {
    mixin(source);
    _.a = stubB;

    assert.strictEqual(_.a(array), 'b');
    assert.strictEqual(_(array).a().value(), 'a');

    reset(_);
  });

  it('should use a default `object` of `this`', function() {
    var object = lodashStable.create(_);
    object.mixin(source);

    assert.strictEqual(object.a(array), 'a');
    assert.ok(!('a' in _));
    assert.ok(!('a' in prototype));

    reset(_);
  });

  it('should accept an `object`', function() {
    var object = {};
    mixin(object, source);
    assert.strictEqual(object.a(array), 'a');
  });

  it('should accept a function `object`', function() {
    mixin(Wrapper, source);

    var wrapped = Wrapper(array),
        actual = wrapped.a();

    assert.strictEqual(actual.value(), 'a');
    assert.ok(actual instanceof Wrapper);

    reset(Wrapper);
  });

  it('should return `object`', function() {
    var object = {};
    assert.strictEqual(mixin(object, source), object);
    assert.strictEqual(mixin(Wrapper, source), Wrapper);
    assert.strictEqual(mixin(), _);

    reset(Wrapper);
  });

  it('should not assign inherited `source` methods', function() {
    function Foo() {}
    Foo.prototype.a = noop;

    var object = {};
    assert.strictEqual(mixin(object, new Foo), object);
  });

  it('should accept an `options`', function() {
    function message(func, chain) {
      return (func === _ ? 'lodash' : 'given') + ' function should ' + (chain ? '' : 'not ') + 'chain';
    }

    lodashStable.each([_, Wrapper], function(func) {
      lodashStable.each([{ 'chain': false }, { 'chain': true }], function(options) {
        if (func === _) {
          mixin(source, options);
        } else {
          mixin(func, source, options);
        }
        var wrapped = func(array),
            actual = wrapped.a();

        if (options.chain) {
          assert.strictEqual(actual.value(), 'a', message(func, true));
          assert.ok(actual instanceof func, message(func, true));
        } else {
          assert.strictEqual(actual, 'a', message(func, false));
          assert.notOk(actual instanceof func, message(func, false));
        }
        reset(func);
      });
    });
  });

  it('should not extend lodash when an `object` is given with an empty `options` object', function() {
    mixin({ 'a': noop }, {});
    assert.ok(!('a' in _));
    reset(_);
  });

  it('should not error for non-object `options` values', function() {
    var pass = true;

    try {
      mixin({}, source, 1);
    } catch (e) {
      pass = false;
    }
    assert.ok(pass);

    pass = true;

    try {
      mixin(source, 1);
    } catch (e) {
      pass = false;
    }
    assert.ok(pass);

    reset(_);
  });

  it('should not return the existing wrapped value when chaining', function() {
    lodashStable.each([_, Wrapper], function(func) {
      if (func === _) {
        var wrapped = _(source),
            actual = wrapped.mixin();

        assert.strictEqual(actual.value(), _);
      }
      else {
        wrapped = _(func);
        actual = wrapped.mixin(source);
        assert.notStrictEqual(actual, wrapped);
      }
      reset(func);
    });
  });

  it('should produce methods that work in a lazy sequence', function() {
    mixin({ 'a': countBy, 'b': filter });

    var array = lodashStable.range(LARGE_ARRAY_SIZE),
        actual = _(array).a().map(square).b(isEven).take().value();

    assert.deepEqual(actual, _.take(_.b(_.map(_.a(array), square), isEven)));

    reset(_);
  });
});