"use strict";

const bind = require("../../src/deps/fp/bind");

describe('bind', function () {
  function Foo(x) {
    this.x = x;
  }

  function add(x) {
    return this.x + x;
  }

  function Bar(x, y) {
    this.x = x;
    this.y = y;
  }

  Bar.prototype = new Foo();

  Bar.prototype.getX = function () {
    return 'prototype getX';
  };

  it('returns a function', function () {
    eq(typeof bind(add, Foo), 'function');
  });
  it('returns a function bound to the specified context object', function () {
    const f = new Foo(12);

    function isFoo() {
      return this instanceof Foo;
    }

    const isFooBound = bind(isFoo, f);
    eq(isFoo(), false);
    eq(isFooBound(), true);
  });
  it('works with built-in types', function () {
    const abc = bind(String.prototype.toLowerCase, 'ABCDEFG');
    eq(typeof abc, 'function');
    eq(abc(), 'abcdefg');
  });
  it('works with user-defined types', function () {
    const f = new Foo(12);

    function getX() {
      return this.x;
    }

    const getXFooBound = bind(getX, f);
    eq(getXFooBound(), 12);
  });
  it('works with plain objects', function () {
    const pojso = {
      x: 100
    };

    function incThis() {
      return this.x + 1;
    }

    const incPojso = bind(incThis, pojso);
    eq(typeof incPojso, 'function');
    eq(incPojso(), 101);
  });
  it('does not interfere with existing object methods', function () {
    const b = new Bar('a', 'b');

    function getX() {
      return this.x;
    }

    const getXBarBound = bind(getX, b);
    eq(b.getX(), 'prototype getX');
    eq(getXBarBound(), 'a');
  });
  it('is curried', function () {
    const f = new Foo(1);
    eq(bind(add)(f)(10), 11);
  });
  it('preserves arity', function () {
    const f0 = function f0() {
      return 0;
    };

    const f1 = function f1(a) {
      return a;
    };

    const f2 = function f2(a, b) {
      return a + b;
    };

    const f3 = function f3(a, b, c) {
      return a + b + c;
    };

    eq(bind(f0, {}).length, 0);
    eq(bind(f1, {}).length, 1);
    eq(bind(f2, {}).length, 2);
    eq(bind(f3, {}).length, 3);
  });
});