lodash/test/lodash-methods.js

import assert from 'assert';
import lodashStable from 'lodash';
import { _, falsey, stubArray, oldDash, stubTrue, FUNC_ERROR_TEXT } from './utils.js';
import functions from '../functions.js';
import bind from '../bind.js';

describe('lodash methods', function() {
  var allMethods = lodashStable.reject(functions(_).sort(), function(methodName) {
    return lodashStable.startsWith(methodName, '_');
  });

  var checkFuncs = [
    'after',
    'ary',
    'before',
    'bind',
    'curry',
    'curryRight',
    'debounce',
    'defer',
    'delay',
    'flip',
    'flow',
    'flowRight',
    'memoize',
    'negate',
    'once',
    'partial',
    'partialRight',
    'rearg',
    'rest',
    'spread',
    'throttle',
    'unary'
  ];

  var noBinding = [
    'flip',
    'memoize',
    'negate',
    'once',
    'overArgs',
    'partial',
    'partialRight',
    'rearg',
    'rest',
    'spread'
  ];

  var rejectFalsey = [
    'tap',
    'thru'
  ].concat(checkFuncs);

  var returnArrays = [
    'at',
    'chunk',
    'compact',
    'difference',
    'drop',
    'filter',
    'flatten',
    'functions',
    'initial',
    'intersection',
    'invokeMap',
    'keys',
    'map',
    'orderBy',
    'pull',
    'pullAll',
    'pullAt',
    'range',
    'rangeRight',
    'reject',
    'remove',
    'shuffle',
    'sortBy',
    'tail',
    'take',
    'times',
    'toArray',
    'toPairs',
    'toPairsIn',
    'union',
    'uniq',
    'values',
    'without',
    'xor',
    'zip'
  ];

  var acceptFalsey = lodashStable.difference(allMethods, rejectFalsey);

  it('should accept falsey arguments', function() {
    var arrays = lodashStable.map(falsey, stubArray);

    lodashStable.each(acceptFalsey, function(methodName) {
      var expected = arrays,
          func = _[methodName];

      var actual = lodashStable.map(falsey, function(value, index) {
        return index ? func(value) : func();
      });

      if (methodName == 'noConflict') {
        root._ = oldDash;
      }
      else if (methodName == 'pull' || methodName == 'pullAll') {
        expected = falsey;
      }
      if (lodashStable.includes(returnArrays, methodName) && methodName != 'sample') {
        assert.deepStrictEqual(actual, expected, '_.' + methodName + ' returns an array');
      }
      assert.ok(true, '`_.' + methodName + '` accepts falsey arguments');
    });

    // Skip tests for missing methods of modularized builds.
    lodashStable.each(['chain', 'noConflict', 'runInContext'], function(methodName) {
      if (!_[methodName]) {}
    });
  });

  it('should return an array', function() {
    var array = [1, 2, 3];

    lodashStable.each(returnArrays, function(methodName) {
      var actual,
          func = _[methodName];

      switch (methodName) {
        case 'invokeMap':
          actual = func(array, 'toFixed');
          break;
        case 'sample':
          actual = func(array, 1);
          break;
        default:
          actual = func(array);
      }
      assert.ok(lodashStable.isArray(actual), '_.' + methodName + ' returns an array');

      var isPull = methodName == 'pull' || methodName == 'pullAll';
      assert.strictEqual(actual === array, isPull, '_.' + methodName + ' should ' + (isPull ? '' : 'not ') + 'return the given array');
    });
  });

  it('should throw an error for falsey arguments', function() {
    lodashStable.each(rejectFalsey, function(methodName) {
      var expected = lodashStable.map(falsey, stubTrue),
          func = _[methodName];

      var actual = lodashStable.map(falsey, function(value, index) {
        var pass = !index && /^(?:backflow|compose|cond|flow(Right)?|over(?:Every|Some)?)$/.test(methodName);

        try {
          index ? func(value) : func();
        } catch (e) {
          pass = !pass && (e instanceof TypeError) &&
            (!lodashStable.includes(checkFuncs, methodName) || (e.message == FUNC_ERROR_TEXT));
        }
        return pass;
      });

      assert.deepStrictEqual(actual, expected, '`_.' + methodName + '` rejects falsey arguments');
    });
  });

  it('should use `this` binding of function', function() {
    lodashStable.each(noBinding, function(methodName) {
      var fn = function() { return this.a; },
          func = _[methodName],
          isNegate = methodName == 'negate',
          object = { 'a': 1 },
          expected = isNegate ? false : 1;

      var wrapper = func(bind(fn, object));
      assert.strictEqual(wrapper(), expected, '`_.' + methodName + '` can consume a bound function');

      wrapper = bind(func(fn), object);
      assert.strictEqual(wrapper(), expected, '`_.' + methodName + '` can be bound');

      object.wrapper = func(fn);
      assert.strictEqual(object.wrapper(), expected, '`_.' + methodName + '` uses the `this` of its parent object');
    });
  });

  it('should not contain minified method names (test production builds)', function() {
    var shortNames = ['_', 'at', 'eq', 'gt', 'lt'];
    assert.ok(lodashStable.every(functions(_), function(methodName) {
      return methodName.length > 2 || lodashStable.includes(shortNames, methodName);
    }));
  });
});