text: var arity0 = require('./0'),
    arity1 = require('./1'),
    arity2 = require('./2'),
    arity3 = require('./3'),
    arity4 = require('./4'),
    arity5 = require('./5'),
    arityN = require('./N'),
    spy = require('sinon').spy(),
    expect = require('expect.js');
  
  function createArray(l) {
    var arr = [];
    for (var i = 0; i < l; i++) {
      arr.push(i);
    }
    return arr;
  }
  
  function hasArity(wrapped, fn, l) {
    var arr = createArray(l);
    expect(wrapped).to.be.a('function');
    expect(wrapped.length).to.be.eql(l);
    wrapped.call(null, arr);
    expect(fn.calledWith.call(fn, arr)).to.be.ok();
  }
  
  describe('arity-function', () => {
    describe('#arity0', () => {
      it('should return a function with length 0', () => {
        var spy0 = arity0(spy);
        hasArity(spy0, spy, 0);
      });
    });
  
    describe('#arity1', () => {
      it('should return a function with length 1', () => {
        var spy1 = arity1(spy);
        hasArity(spy1, spy, 1);
      });
    });
  
    describe('#arity2', () => {
      it('should return a function with length 2', () => {
        var spy2 = arity2(spy);
        hasArity(spy2, spy, 2);
      });
    });
  
    describe('#arity3', () => {
      it('should return a function with length 3', () => {
        var spy3 = arity3(spy);
        hasArity(spy3, spy, 3);
      });
    });
  
    describe('#arity4', () => {
      it('should return a function with length 4', () => {
        var spy4 = arity4(spy);
        hasArity(spy4, spy, 4);
      });
    });
  
    describe('#arity5', () => {
      it('should return a function with length 5', () => {
        var spy5 = arity5(spy);
        hasArity(spy5, spy, 5);
      });
    });
  
    describe('#arityN', () => {
      it('should return a function with length N', () => {
        var spy0 = arityN(spy, 0);
        hasArity(spy0, spy, 0);
  
        var spy1 = arityN(spy, 1);
        hasArity(spy1, spy, 1);
  
        var spy2 = arityN(spy, 2);
        hasArity(spy2, spy, 2);
  
        var spy3 = arityN(spy, 3);
        hasArity(spy3, spy, 3);
  
        var spy4 = arityN(spy, 4);
        hasArity(spy4, spy, 4);
  
        var spy5 = arityN(spy, 5);
        hasArity(spy5, spy, 5);
  
        var spyX = arityN(spy, undefined);
        hasArity(spyX, spy, 0);
        spyX = arityN(spy, null);
        hasArity(spyX, spy, 0);
  
        var newFn = arityN(function(a,b,c,d,e,f,g,h,i,j,k){ return true; }, 9);
        expect(newFn.length).to.be.eql(11);
        expect(newFn()).to.be.eql(true);
      });
    });
  });
  