es-iterator-helpers
Version:
An ESnext spec-compliant iterator helpers shim/polyfill/replacement that works as far down as ES3.
319 lines (276 loc) • 10 kB
JavaScript
;
var defineProperties = require('define-properties');
var test = require('tape');
var callBind = require('call-bind');
var functionsHaveNames = require('functions-have-names')();
var hasStrictMode = require('has-strict-mode')();
var forEach = require('for-each');
var debug = require('object-inspect');
var v = require('es-value-fixtures');
var hasSymbols = require('has-symbols/shams')();
var iterate = require('iterate-iterator');
var index = require('../Iterator.prototype.reduce');
var impl = require('../Iterator.prototype.reduce/implementation');
var fnName = 'reduce';
var isEnumerable = Object.prototype.propertyIsEnumerable;
var testIterator = require('./helpers/testIterator');
module.exports = {
tests: function (reduce, name, t) {
t['throws'](
function () { return new reduce(); }, // eslint-disable-line new-cap
TypeError,
'`' + name + '` is not a constructor'
);
forEach(v.primitives.concat(v.objects), function (nonIterator) {
t['throws'](
function () { iterate(reduce(nonIterator, function () {})); },
TypeError,
debug(nonIterator) + ' is not an Object with a callable `next` method'
);
var badNext = { next: nonIterator };
t['throws'](
function () { iterate(reduce(badNext, function () {})); },
TypeError,
debug(badNext) + ' is not an Object with a callable `next` method'
);
});
forEach(v.nonFunctions, function (nonFunction) {
t['throws'](
function () { reduce({ next: function () {} }, nonFunction); },
TypeError,
debug(nonFunction) + ' is not a function'
);
});
t.test('actual iteration', { skip: !hasSymbols }, function (st) {
var arr = [1, 2, 3];
var iterator = callBind(arr[Symbol.iterator], arr);
st['throws'](
function () { return new reduce(iterator()); }, // eslint-disable-line new-cap
TypeError,
'`' + name + '` iterator is not a constructor'
);
st['throws'](
function () { return new reduce(iterator(), function () {}); }, // eslint-disable-line new-cap
TypeError,
'`' + name + '` iterator is not a constructor'
);
testIterator(iterator(), [1, 2, 3], st, 'original');
var results = [];
var ret = reduce(
iterator(),
function (acc, x, i) {
results.push({ acc: acc, value: x, count: i, 'this': this, args: arguments.length });
return acc + x;
}
);
st.equal(ret, 6, 'returns sum of all numbers');
st.deepEqual(
results,
[
{ acc: 1, value: 2, count: 1, 'this': undefined, args: 3 },
{ acc: 3, value: 3, count: 2, 'this': undefined, args: 3 }
],
'reduce callback receives the expected values without initialValue'
);
var results2 = [];
var ret2 = reduce(
iterator(),
function (acc, x, i) {
results2.push({ acc: acc, value: x, count: i, 'this': this, args: arguments.length });
return acc + x;
},
10
);
st.equal(ret2, 16, 'returns sum of all numbers plus initialValue');
st.deepEqual(
results2,
[
{ acc: 10, value: 1, count: 0, 'this': undefined, args: 3 },
{ acc: 11, value: 2, count: 1, 'this': undefined, args: 3 },
{ acc: 13, value: 3, count: 2, 'this': undefined, args: 3 }
],
'reduce callback receives the expected values with initialValue'
);
st.test('test262: test/built-ins/Iterator/prototype/reduce/reducer-args-initial-value', function (s2t) {
var assertionCount = 0;
var result = reduce(
['a', 'b', 'c'][Symbol.iterator](),
function (memo, value, count) {
if (value === 'a') {
s2t.equal(memo, 'start', 'memo is initial value for first call');
s2t.equal(count, 0);
} else if (value === 'b') {
s2t.equal(memo, 'a', 'memo is previous return');
s2t.equal(count, 1);
} else if (value === 'c') {
s2t.equal(memo, 'b', 'memo is previous return');
s2t.equal(count, 2);
} else {
s2t.fail('unexpected value');
}
assertionCount += 1;
return value;
},
'start'
);
s2t.equal(result, 'c', 'reduce returns last value');
s2t.equal(assertionCount, 3, 'reducer called three times');
s2t.end();
});
st.test('test262: test/built-ins/Iterator/prototype/reduce/reducer-args-no-initial-value', function (s2t) {
var assertionCount = 0;
var result = reduce(
['a', 'b', 'c'][Symbol.iterator](),
function (memo, value, count) {
if (value === 'b') {
s2t.equal(memo, 'a', 'memo is first value when no initial');
s2t.equal(count, 1);
} else if (value === 'c') {
s2t.equal(memo, 'b', 'memo is previous return');
s2t.equal(count, 2);
} else {
s2t.fail('unexpected value');
}
assertionCount += 1;
return value;
}
);
s2t.equal(result, 'c', 'reduce returns last value');
s2t.equal(assertionCount, 2, 'reducer called twice');
s2t.end();
});
st.test('test262: test/built-ins/Iterator/prototype/reduce/reducer-this', function (s2t) {
var expectedThis = (function () { return this; }()); // eslint-disable-line no-invalid-this
var assertionCount = 0;
var result = reduce(
[0, 1][Symbol.iterator](),
function () {
s2t.equal(this, expectedThis, 'reducer this is undefined'); // eslint-disable-line no-invalid-this
assertionCount += 1;
return 0;
}
);
s2t.equal(result, 0);
s2t.equal(assertionCount, 1, 'reducer called once');
s2t.end();
});
st.test('test262: test/built-ins/Iterator/prototype/reduce/reducer-throws', function (s2t) {
var returnCount = 0;
var testIter = {
next: function () {
return { done: false, value: 1 };
},
'return': function () {
returnCount += 1;
return { done: true };
}
};
var callbackCount = 0;
s2t['throws'](
function () {
reduce(testIter, function () {
callbackCount += 1;
throw new SyntaxError('reducer threw');
}, 0);
},
SyntaxError
);
s2t.equal(callbackCount, 1, 'reducer called once');
s2t.equal(returnCount, 1, 'iterator closed when reducer throws');
s2t.end();
});
st.test('test262: test/built-ins/Iterator/prototype/reduce/iterator-already-exhausted-initial-value', function (s2t) {
var iter = [][Symbol.iterator]();
var callbackCount = 0;
var result = reduce(iter, function () {
callbackCount += 1;
return 'called';
}, 'initial');
s2t.equal(result, 'initial', 'reduce returns initial value for empty iterator');
s2t.equal(callbackCount, 0, 'reducer not called');
s2t.end();
});
st.test('test262: test/built-ins/Iterator/prototype/reduce/iterator-already-exhausted-no-initial-value', function (s2t) {
var iter = [][Symbol.iterator]();
s2t['throws'](
function () {
reduce(iter, function () {});
},
TypeError,
'reduce throws TypeError for empty iterator without initial value'
);
s2t.end();
});
st.test('test262: test/built-ins/Iterator/prototype/reduce/iterator-yields-once-initial-value', function (s2t) {
var callbackCount = 0;
var result = reduce(
[42][Symbol.iterator](),
function (memo, value) {
callbackCount += 1;
return memo + value;
},
10
);
s2t.equal(result, 52, 'reduce returns sum');
s2t.equal(callbackCount, 1, 'reducer called once');
s2t.end();
});
st.test('test262: test/built-ins/Iterator/prototype/reduce/iterator-yields-once-no-initial-value', function (s2t) {
var callbackCount = 0;
var result = reduce(
[42][Symbol.iterator](),
function () {
callbackCount += 1;
return 'called';
}
);
s2t.equal(result, 42, 'reduce returns sole value');
s2t.equal(callbackCount, 0, 'reducer not called');
s2t.end();
});
st.test('test262: test/built-ins/Iterator/prototype/reduce/reducer-memo-can-be-any-type', function (s2t) {
// test various memo types
s2t.equal(reduce([1][Symbol.iterator](), function (m) { return m; }, null), null, 'null memo');
s2t.equal(reduce([1][Symbol.iterator](), function (m) { return m; }, undefined), undefined, 'undefined memo');
s2t.equal(reduce([1][Symbol.iterator](), function (m) { return m; }, 0), 0, 'number memo');
s2t.equal(reduce([1][Symbol.iterator](), function (m) { return m; }, ''), '', 'string memo');
s2t.equal(reduce([1][Symbol.iterator](), function (m) { return m; }, false), false, 'boolean memo');
var obj = {};
s2t.equal(reduce([1][Symbol.iterator](), function (m) { return m; }, obj), obj, 'object memo');
s2t.end();
});
st.end();
});
},
index: function () {
test('Iterator.prototype.' + fnName + ': index', function (t) {
module.exports.tests(index, 'Iterator.prototype.' + fnName, t);
t.end();
});
},
implementation: function () {
test('Iterator.prototype.' + fnName + ': implementation', function (t) {
module.exports.tests(callBind(impl), 'Iterator.prototype.' + fnName, t);
t.end();
});
},
shimmed: function () {
test('Iterator.prototype.' + fnName + ': shimmed', function (t) {
t.test('Function name', { skip: !functionsHaveNames }, function (st) {
st.equal(Iterator.prototype[fnName].name, fnName, 'Iterator#' + fnName + ' has name "' + fnName + '"');
st.end();
});
t.test('enumerability', { skip: !defineProperties.supportsDescriptors }, function (et) {
et.equal(false, isEnumerable.call(Iterator.prototype, fnName), 'Iterator#' + fnName + ' is not enumerable');
et.end();
});
t.test('bad string/this value', { skip: !hasStrictMode }, function (st) {
st['throws'](function () { return Iterator.prototype[fnName].call(undefined, 'a'); }, TypeError, 'undefined is not an object');
st['throws'](function () { return Iterator.prototype[fnName].call(null, 'a'); }, TypeError, 'null is not an object');
st.end();
});
module.exports.tests(callBind(Iterator.prototype[fnName]), 'Iterator.prototype.' + fnName, t);
t.end();
});
}
};