before.js

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

describe('before', function() {
  function before(n, times) {
    var count = 0;
    lodashStable.times(times, _.before(n, function() { count++; }));
    return count;
  }

  it('should create a function that invokes `func` after `n` calls', function() {
    assert.strictEqual(before(5, 4), 4, 'before(n) should invoke `func` before being called `n` times');
    assert.strictEqual(before(5, 6), 4, 'before(n) should not invoke `func` after being called `n - 1` times');
    assert.strictEqual(before(0, 0), 0, 'before(0) should not invoke `func` immediately');
    assert.strictEqual(before(0, 1), 0, 'before(0) should not invoke `func` when called');
  });

  it('should coerce `n` values of `NaN` to `0`', function() {
    assert.strictEqual(before(NaN, 1), 0);
  });

  it('should use `this` binding of function', function() {
    var before = _.before(2, function() { return ++this.count; }),
        object = { 'before': before, 'count': 0 };

    object.before();
    assert.strictEqual(object.before(), 1);
    assert.strictEqual(object.count, 1);
  });
});