s-function.js
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/* global describe, it, expect, beforeEach */
describe('Function', function () {
'use strict';
describe('#apply()', function () {
it('works with arraylike objects', function () {
var arrayLike = { length: 4, 0: 1, 2: 4, 3: true };
var expectedArray = [1, undefined, 4, true];
var actualArray = (function () {
return Array.prototype.slice.apply(arguments);
}.apply(null, arrayLike));
expect(actualArray).toEqual(expectedArray);
});
});
describe('#bind()', function () {
var actual;
var testSubject = {
push: function (o) {
this.a.push(o);
}
};
var func = function func() {
Array.prototype.forEach.call(arguments, function (a) {
this.push(a);
}, this);
return this;
};
beforeEach(function () {
actual = [];
testSubject.a = [];
});
it('binds properly without a context', function () {
var context;
testSubject.func = function () {
context = this;
}.bind();
testSubject.func();
expect(context).toBe(function () { return this; }.call());
});
it('binds properly without a context, and still supplies bound arguments', function () {
var a, context;
testSubject.func = function () {
a = Array.prototype.slice.call(arguments);
context = this;
}.bind(undefined, 1, 2, 3);
testSubject.func(1, 2, 3);
expect(a).toEqual([1, 2, 3, 1, 2, 3]);
expect(context).toBe(function () { return this; }.call());
});
it('binds a context properly', function () {
testSubject.func = func.bind(actual);
testSubject.func(1, 2, 3);
expect(actual).toEqual([1, 2, 3]);
expect(testSubject.a).toEqual([]);
});
it('binds a context and supplies bound arguments', function () {
testSubject.func = func.bind(actual, 1, 2, 3);
testSubject.func(4, 5, 6);
expect(actual).toEqual([1, 2, 3, 4, 5, 6]);
expect(testSubject.a).toEqual([]);
});
it('returns properly without binding a context', function () {
testSubject.func = function () {
return this;
}.bind();
var context = testSubject.func();
expect(context).toBe(function () { return this; }.call());
});
it('returns properly without binding a context, and still supplies bound arguments', function () {
var context;
testSubject.func = function () {
context = this;
return Array.prototype.slice.call(arguments);
}.bind(undefined, 1, 2, 3);
actual = testSubject.func(1, 2, 3);
expect(context).toBe(function () { return this; }.call());
expect(actual).toEqual([1, 2, 3, 1, 2, 3]);
});
it('returns properly while binding a context properly', function () {
var ret;
testSubject.func = func.bind(actual);
ret = testSubject.func(1, 2, 3);
expect(ret).toBe(actual);
expect(ret).not.toBe(testSubject);
});
it('returns properly while binding a context and supplies bound arguments', function () {
var ret;
testSubject.func = func.bind(actual, 1, 2, 3);
ret = testSubject.func(4, 5, 6);
expect(ret).toBe(actual);
expect(ret).not.toBe(testSubject);
});
it('has the new instance\'s context as a constructor', function () {
var actualContext;
var expectedContext = { foo: 'bar' };
testSubject.Func = function () {
actualContext = this;
}.bind(expectedContext);
var result = new testSubject.Func();
expect(result).toBeTruthy();
expect(actualContext).not.toBe(expectedContext);
});
it('passes the correct arguments as a constructor', function () {
var expected = { name: 'Correct' };
testSubject.Func = function (arg) {
expect(this.hasOwnProperty('name')).toBe(false);
return arg;
}.bind({ name: 'Incorrect' });
var ret = new testSubject.Func(expected);
expect(ret).toBe(expected);
});
it('returns the return value of the bound function when called as a constructor', function () {
var oracle = [1, 2, 3];
var Subject = function () {
expect(this).not.toBe(oracle);
return oracle;
}.bind(null);
var result = new Subject();
expect(result).toBe(oracle);
});
it('returns the correct value if constructor returns primitive', function () {
var Subject = function (oracle) {
expect(this).not.toBe(oracle);
return oracle;
}.bind(null);
var primitives = ['asdf', null, true, 1];
for (var i = 0; i < primitives.length; ++i) {
expect(new Subject(primitives[i])).not.toBe(primitives[i]);
}
var objects = [[1, 2, 3], {}, function () {}];
for (var j = 0; j < objects.length; ++j) {
expect(new Subject(objects[j])).toBe(objects[j]);
}
});
it('returns the value that instance of original "class" when called as a constructor', function () {
var ClassA = function (x) {
this.name = x || 'A';
};
var ClassB = ClassA.bind(null, 'B');
var result = new ClassB();
expect(result instanceof ClassA).toBe(true);
expect(result instanceof ClassB).toBe(true);
});
it('sets a correct length without thisArg', function () {
var Subject = function (a, b, c) { return a + b + c; }.bind();
expect(Subject.length).toBe(3);
});
it('sets a correct length with thisArg', function () {
var Subject = function (a, b, c) { return a + b + c + this.d; }.bind({ d: 1 });
expect(Subject.length).toBe(3);
});
it('sets a correct length with thisArg and first argument', function () {
var Subject = function (a, b, c) { return a + b + c + this.d; }.bind({ d: 1 }, 1);
expect(Subject.length).toBe(2);
});
it('sets a correct length without thisArg and first argument', function () {
var Subject = function (a, b, c) { return a + b + c; }.bind(undefined, 1);
expect(Subject.length).toBe(2);
});
it('sets a correct length without thisArg and too many argument', function () {
var Subject = function (a, b, c) { return a + b + c; }.bind(undefined, 1, 2, 3, 4);
expect(Subject.length).toBe(0);
});
});
});