lodash/test/map.js

import assert from 'assert';
import lodashStable from 'lodash';
import { identity, falsey, stubArray, document, noop, LARGE_ARRAY_SIZE, square } from './utils.js';
import map from '../map.js';

describe('map', function() {
  var array = [1, 2];

  it('should map values in `collection` to a new array', function() {
    var object = { 'a': 1, 'b': 2 },
        expected = ['1', '2'];

    assert.deepStrictEqual(map(array, String), expected);
    assert.deepStrictEqual(map(object, String), expected);
  });

  it('should work with `_.property` shorthands', function() {
    var objects = [{ 'a': 'x' }, { 'a': 'y' }];
    assert.deepStrictEqual(map(objects, 'a'), ['x', 'y']);
  });

  it('should iterate over own string keyed properties of objects', function() {
    function Foo() {
      this.a = 1;
    }
    Foo.prototype.b = 2;

    var actual = map(new Foo, identity);
    assert.deepStrictEqual(actual, [1]);
  });

  it('should use `_.identity` when `iteratee` is nullish', function() {
    var object = { 'a': 1, 'b': 2 },
        values = [, null, undefined],
        expected = lodashStable.map(values, lodashStable.constant([1, 2]));

    lodashStable.each([array, object], function(collection) {
      var actual = lodashStable.map(values, function(value, index) {
        return index ? map(collection, value) : map(collection);
      });

      assert.deepStrictEqual(actual, expected);
    });
  });

  it('should accept a falsey `collection`', function() {
    var expected = lodashStable.map(falsey, stubArray);

    var actual = lodashStable.map(falsey, function(collection, index) {
      try {
        return index ? map(collection) : map();
      } catch (e) {}
    });

    assert.deepStrictEqual(actual, expected);
  });

  it('should treat number values for `collection` as empty', function() {
    assert.deepStrictEqual(map(1), []);
  });

  it('should treat a nodelist as an array-like object', function() {
    if (document) {
      var actual = map(document.getElementsByTagName('body'), function(element) {
        return element.nodeName.toLowerCase();
      });

      assert.deepStrictEqual(actual, ['body']);
    }
  });

  it('should work with objects with non-number length properties', function() {
    var value = { 'value': 'x' },
        object = { 'length': { 'value': 'x' } };

    assert.deepStrictEqual(map(object, identity), [value]);
  });

  it('should return a wrapped value when chaining', function() {
    assert.ok(_(array).map(noop) instanceof _);
  });

  it('should provide correct `predicate` arguments in a lazy sequence', function() {
    var args,
        array = lodashStable.range(LARGE_ARRAY_SIZE + 1),
        expected = [1, 0, map(array.slice(1), square)];

    _(array).slice(1).map(function(value, index, array) {
      args || (args = slice.call(arguments));
    }).value();

    assert.deepEqual(args, [1, 0, array.slice(1)]);

    args = undefined;
    _(array).slice(1).map(square).map(function(value, index, array) {
      args || (args = slice.call(arguments));
    }).value();

    assert.deepEqual(args, expected);

    args = undefined;
    _(array).slice(1).map(square).map(function(value, index) {
      args || (args = slice.call(arguments));
    }).value();

    assert.deepEqual(args, expected);

    args = undefined;
    _(array).slice(1).map(square).map(function(value) {
      args || (args = slice.call(arguments));
    }).value();

    assert.deepEqual(args, [1]);

    args = undefined;
    _(array).slice(1).map(square).map(function() {
      args || (args = slice.call(arguments));
    }).value();

    assert.deepEqual(args, expected);
  });
});