import assert from 'assert';
import lodashStable from 'lodash';
import { _, symbol } from './utils.js';

describe('math operator methods', function() {
  lodashStable.each(['add', 'divide', 'multiply', 'subtract'], function(methodName) {
    var func = _[methodName],
        isAddSub = methodName == 'add' || methodName == 'subtract';

    it('`_.' + methodName + '` should return `' + (isAddSub ? 0 : 1) + '` when no arguments are given', function() {
      assert.strictEqual(func(), isAddSub ? 0 : 1);
    });

    it('`_.' + methodName + '` should work with only one defined argument', function() {
      assert.strictEqual(func(6), 6);
      assert.strictEqual(func(6, undefined), 6);
      assert.strictEqual(func(undefined, 4), 4);
    });

    it('`_.' + methodName + '` should preserve the sign of `0`', function() {
      var values = [0, '0', -0, '-0'],
          expected = [[0, Infinity], ['0', Infinity], [-0, -Infinity], ['-0', -Infinity]];

      lodashStable.times(2, function(index) {
        var actual = lodashStable.map(values, function(value) {
          var result = index ? func(undefined, value) : func(value);
          return [result, 1 / result];
        });

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

    it('`_.' + methodName + '` should convert objects to `NaN`', function() {
      assert.deepStrictEqual(func(0, {}), NaN);
      assert.deepStrictEqual(func({}, 0), NaN);
    });

    it('`_.' + methodName + '` should convert symbols to `NaN`', function() {
      if (Symbol) {
        assert.deepStrictEqual(func(0, symbol), NaN);
        assert.deepStrictEqual(func(symbol, 0), NaN);
      }
    });

    it('`_.' + methodName + '` should return an unwrapped value when implicitly chaining', function() {
      var actual = _(1)[methodName](2);
      assert.notOk(actual instanceof _);
    });

    it('`_.' + methodName + '` should return a wrapped value when explicitly chaining', function() {
      var actual = _(1).chain()[methodName](2);
      assert.ok(actual instanceof _);
    });
  });
});