es-iterator-helpers
Version:
An ESnext spec-compliant iterator helpers shim/polyfill/replacement that works as far down as ES3.
323 lines (273 loc) • 9.33 kB
JavaScript
;
var defineProperties = require('define-properties');
var test = require('tape');
var callBind = require('call-bind');
var functionsHaveNames = require('functions-have-names')();
var hasProto = require('has-proto')();
var forEach = require('for-each');
var debug = require('object-inspect');
var v = require('es-value-fixtures');
var hasSymbols = require('has-symbols/shams')();
var hasPropertyDescriptors = require('has-property-descriptors')();
var mockProperty = require('mock-property');
var index = require('../Iterator.from');
var impl = require('../Iterator.from/implementation');
var isEnumerable = Object.prototype.propertyIsEnumerable;
var testIterator = require('./helpers/testIterator');
var $Iterator = require('../Iterator/implementation');
var iterProto = require('iterator.prototype');
var getCodePoints = function getCodePoints(str) {
var chars = [];
for (var i = 0; i < str.length; i++) {
var c1 = str.charCodeAt(i);
if (c1 >= 0xD800 && c1 < 0xDC00 && i + 1 < str.length) {
var c2 = str.charCodeAt(i + 1);
if (c2 >= 0xDC00 && c2 < 0xE000) {
chars.push(str.charAt(i) + str.charAt(i + 1));
i += 1;
continue; // eslint-disable-line no-continue, no-restricted-syntax
}
}
chars.push(str.charAt(i));
}
return chars;
};
module.exports = {
tests: function (from, name, t) {
t['throws'](
function () { return new from(); }, // eslint-disable-line new-cap
TypeError,
'`' + name + '` itself is not a constructor'
);
t['throws'](
function () { return new from({}); }, // eslint-disable-line new-cap
TypeError,
'`' + name + '` itself is not a constructor, with an argument'
);
forEach(v.primitives.concat(v.objects), function (nonIterator) {
if (typeof nonIterator !== 'string') {
t['throws'](
function () { from(nonIterator).next(); },
TypeError,
debug(nonIterator) + ' is not an iterable Object'
);
}
});
t.test('actual iteration', { skip: !hasSymbols }, function (st) {
forEach(v.nonFunctions, function (nonFunction) {
var badIterable = {};
badIterable[Symbol.iterator] = nonFunction;
st['throws'](
function () { from(badIterable).next(); },
TypeError,
debug(badIterable) + ' is not a function'
);
});
// st['throws'](
// function () { return new from([]); }, // eslint-disable-line new-cap
// RangeError,
// '`' + name + '` iterator is not a constructor'
// );
forEach(v.strings, function (string) {
var stringIt = from(string);
testIterator(stringIt, getCodePoints(string), st, 'string iterator: ' + debug(string));
});
var arrayIt = from([1, 2, 3]);
st.equal(typeof arrayIt.next, 'function', 'has a `next` function');
st.test('__proto__ is Iterator.prototype', { skip: !hasProto }, function (s2t) {
var fakeIterator = {
__proto__: iterProto,
next: function () {}
};
s2t.ok(fakeIterator instanceof $Iterator, 'is an instanceof Iterator');
s2t.equal(typeof fakeIterator.next, 'function', 'fake iterator `.next` is a function');
s2t.equal(from(fakeIterator), fakeIterator, 'returns input when it is an instanceof Iterator');
s2t.end();
});
st.test('real iterators', { skip: !hasSymbols }, function (s2t) {
var iter = [][Symbol.iterator]();
// eslint-disable-next-line no-proto
var arrayIterHasIterProto = hasProto && iter.__proto__.__proto__ !== Object.prototype;
s2t.equal(
from(iter),
iter,
'array iterator becomes itself',
{ skip: !arrayIterHasIterProto && 'node 0.12 - 3 do not have Iterator.prototype in the proto chains' }
);
s2t.end();
});
st.test('observability in a replaced String iterator', function (s2t) {
var originalStringIterator = String.prototype[Symbol.iterator];
var observedType;
s2t.teardown(mockProperty(String.prototype, Symbol.iterator, {
get: function () {
'use strict'; // eslint-disable-line strict, lines-around-directive
observedType = typeof this;
return originalStringIterator;
}
}));
from('');
s2t.equal(observedType, 'string', 'string primitive -> primitive receiver in Symbol.iterator getter');
from(Object(''));
s2t.equal(observedType, 'object', 'boxed string -> boxed string in Symbol.iterator getter');
s2t.end();
});
st.test('262: get-next-method-only-once', { skip: !hasPropertyDescriptors }, function (s2t) {
var nextGets = 0;
var testIter = {
next: function () {
return { done: true, value: undefined };
}
};
Object.defineProperty(testIter, 'next', {
get: function () {
nextGets += 1;
return function () {
return { done: true, value: undefined };
};
}
});
var iter = from(testIter);
s2t.equal(nextGets, 1, 'next retrieved once on creation');
iter.next();
s2t.equal(nextGets, 1, 'next not retrieved again on next()');
iter.next();
s2t.equal(nextGets, 1, 'next still not retrieved again');
s2t.end();
});
st.test('262: get-next-method-throws', { skip: !hasPropertyDescriptors }, function (s2t) {
var testIter = {};
Object.defineProperty(testIter, 'next', {
get: function () {
throw new EvalError('next getter threw');
}
});
s2t['throws'](
function () { from(testIter); },
EvalError,
'throws when getting next throws'
);
s2t.end();
});
st.test('262: iterable-to-iterator-fallback', function (s2t) {
// When Symbol.iterator is null/undefined, treat object as iterator
var iteratorObj = {
next: function () {
return { done: true, value: undefined };
}
};
iteratorObj[Symbol.iterator] = null;
var iter1 = from(iteratorObj);
s2t.equal(typeof iter1.next, 'function', 'iterator with null Symbol.iterator is treated as iterator');
var iteratorObj2 = {
next: function () {
return { done: true, value: undefined };
}
};
iteratorObj2[Symbol.iterator] = undefined;
var iter2 = from(iteratorObj2);
s2t.equal(typeof iter2.next, 'function', 'iterator with undefined Symbol.iterator is treated as iterator');
s2t.end();
});
st.test('262: return-is-forwarded', function (s2t) {
var returnCalls = 0;
var testIter = {
next: function () {
return { done: false, value: 1 };
},
'return': function () {
returnCalls += 1;
return { done: true, value: undefined };
}
};
var iter = from(testIter);
iter.next();
s2t.equal(returnCalls, 0, 'return not called before calling return()');
iter['return']();
s2t.equal(returnCalls, 1, 'return called once after return()');
s2t.end();
});
st.test('262: return-method-returns-iterator-result', function (s2t) {
// When base iterator has no return method, wrapper's return() returns { done: true, value: undefined }
var testIter = {
next: function () {
return { done: false, value: 1 };
}
};
var iter = from(testIter);
iter.next();
var result = iter['return']();
s2t.equal(result.done, true, 'done is true');
s2t.equal(result.value, undefined, 'value is undefined');
s2t.end();
});
st.test('262: get-return-method-throws', { skip: !hasPropertyDescriptors }, function (s2t) {
var testIter = {
next: function () {
return { done: false, value: 1 };
}
};
Object.defineProperty(testIter, 'return', {
get: function () {
throw new SyntaxError('return getter threw');
}
});
var iter = from(testIter);
iter.next();
s2t['throws'](
function () { iter['return'](); },
SyntaxError,
'throws when getting return throws'
);
s2t.end();
});
st.test('262: supports-iterator', function (s2t) {
// Non-iterable iterator objects (no Symbol.iterator, but has next)
var plainIterator = {
next: function () {
return { done: true, value: 42 };
}
};
var iter = from(plainIterator);
s2t.equal(typeof iter.next, 'function', 'wrapped iterator has next method');
var result = iter.next();
s2t.equal(result.done, true, 'done is true');
s2t.equal(result.value, 42, 'value is passed through');
s2t.end();
});
st.test('262: supports-iterable', function (s2t) {
// Iterable objects work
var arr = [1, 2, 3];
testIterator(from(arr), [1, 2, 3], s2t, 'array iterable');
s2t.end();
});
st.end();
});
},
index: function () {
test('Iterator.from: index', function (t) {
module.exports.tests(index, 'Iterator.from', t);
t.end();
});
},
implementation: function () {
test('Iterator.from: implementation', function (t) {
module.exports.tests(impl, 'Iterator.from', t);
t.end();
});
},
shimmed: function () {
test('Iterator.from: shimmed', function (t) {
t.test('Function name', { skip: !functionsHaveNames }, function (st) {
st.equal(Iterator.from.name, 'from', 'Iterator.from has name "from"');
st.end();
});
t.test('enumerability', { skip: !defineProperties.supportsDescriptors }, function (et) {
et.equal(false, isEnumerable.call(Iterator, 'from'), 'Iterator.from is not enumerable');
et.end();
});
module.exports.tests(callBind(Iterator.from, Iterator), 'Iterator.from', t);
t.end();
});
}
};