event-emitters
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JavaScript
;
var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, generator) {
function adopt(value) { return value instanceof P ? value : new P(function (resolve) { resolve(value); }); }
return new (P || (P = Promise))(function (resolve, reject) {
function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
function step(result) { result.done ? resolve(result.value) : adopt(result.value).then(fulfilled, rejected); }
step((generator = generator.apply(thisArg, _arguments || [])).next());
});
};
var __generator = (this && this.__generator) || function (thisArg, body) {
var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
function verb(n) { return function (v) { return step([n, v]); }; }
function step(op) {
if (f) throw new TypeError("Generator is already executing.");
while (_) try {
if (f = 1, y && (t = op[0] & 2 ? y["return"] : op[0] ? y["throw"] || ((t = y["return"]) && t.call(y), 0) : y.next) && !(t = t.call(y, op[1])).done) return t;
if (y = 0, t) op = [op[0] & 2, t.value];
switch (op[0]) {
case 0: case 1: t = op; break;
case 4: _.label++; return { value: op[1], done: false };
case 5: _.label++; y = op[1]; op = [0]; continue;
case 7: op = _.ops.pop(); _.trys.pop(); continue;
default:
if (!(t = _.trys, t = t.length > 0 && t[t.length - 1]) && (op[0] === 6 || op[0] === 2)) { _ = 0; continue; }
if (op[0] === 3 && (!t || (op[1] > t[0] && op[1] < t[3]))) { _.label = op[1]; break; }
if (op[0] === 6 && _.label < t[1]) { _.label = t[1]; t = op; break; }
if (t && _.label < t[2]) { _.label = t[2]; _.ops.push(op); break; }
if (t[2]) _.ops.pop();
_.trys.pop(); continue;
}
op = body.call(thisArg, _);
} catch (e) { op = [6, e]; y = 0; } finally { f = t = 0; }
if (op[0] & 5) throw op[1]; return { value: op[0] ? op[1] : void 0, done: true };
}
};
var __asyncValues = (this && this.__asyncValues) || function (o) {
if (!Symbol.asyncIterator) throw new TypeError("Symbol.asyncIterator is not defined.");
var m = o[Symbol.asyncIterator], i;
return m ? m.call(o) : (o = typeof __values === "function" ? __values(o) : o[Symbol.iterator](), i = {}, verb("next"), verb("throw"), verb("return"), i[Symbol.asyncIterator] = function () { return this; }, i);
function verb(n) { i[n] = o[n] && function (v) { return new Promise(function (resolve, reject) { v = o[n](v), settle(resolve, reject, v.done, v.value); }); }; }
function settle(resolve, reject, d, v) { Promise.resolve(v).then(function(v) { resolve({ value: v, done: d }); }, reject); }
};
Object.defineProperty(exports, "__esModule", { value: true });
var EventEmitter_1 = require("./EventEmitter");
describe('EventEmitter', function () {
/* eslint-disable @typescript-eslint/explicit-function-return-type */
var emitter = new EventEmitter_1.EventEmitter();
beforeEach(function () {
emitter = new EventEmitter_1.EventEmitter();
});
it('updates subscribed listener with statuses as they change', function () {
var current;
emitter.subscribe(function (newVal) {
current = newVal;
});
expect(current).toEqual(undefined);
var secondVal = 2;
emitter.emit(secondVal);
expect(current).toEqual(secondVal);
});
it('supports multiple listeners', function () {
var current1;
var current2;
emitter.subscribe(function (newVal) {
current1 = newVal;
});
emitter.subscribe(function (newVal) {
current2 = newVal;
});
expect(current1).toEqual(undefined);
expect(current2).toEqual(undefined);
var secondVal = 2;
emitter.emit(secondVal);
expect(current1).toEqual(secondVal);
expect(current2).toEqual(secondVal);
});
it('stops updating a listener after `unsubscribe` is called', function () {
var current1;
var current2;
var secondListener = function (newVal) {
current2 = newVal;
};
emitter.subscribe(function (newVal) {
current1 = newVal;
});
emitter.subscribe(secondListener);
expect(current1).toEqual(undefined);
expect(current2).toEqual(undefined);
var secondVal = 2;
emitter.emit(secondVal);
expect(current1).toEqual(secondVal);
expect(current2).toEqual(secondVal);
emitter.unsubscribe(secondListener);
var thirdVal = 3;
emitter.emit(thirdVal);
expect(current1).toEqual(thirdVal);
expect(current2).toEqual(secondVal);
});
it('throws an error when trying to subscribe the same listener twice', function () {
// eslint-disable-next-line @typescript-eslint/no-empty-function
var listener = function () { };
emitter.subscribe(listener);
expect(function () {
emitter.subscribe(listener);
}).toThrow();
});
it('throws an error when trying to unsubscribe a listener that is not listening', function () {
// eslint-disable-next-line @typescript-eslint/no-empty-function
var listener1 = function () { };
// eslint-disable-next-line @typescript-eslint/no-empty-function
var listener2 = function () { };
emitter.subscribe(listener1);
expect(function () {
emitter.unsubscribe(listener2);
}).toThrow();
});
describe('async iterator', function () {
it('can be iterated over in order using "for await" loop', function () { return __awaiter(void 0, void 0, void 0, function () {
function iterate(iterator) {
var iterator_1, iterator_1_1;
var e_1, _a;
return __awaiter(this, void 0, void 0, function () {
var val, e_1_1;
return __generator(this, function (_b) {
switch (_b.label) {
case 0:
_b.trys.push([0, 5, 6, 11]);
iterator_1 = __asyncValues(iterator);
_b.label = 1;
case 1: return [4 /*yield*/, iterator_1.next()];
case 2:
if (!(iterator_1_1 = _b.sent(), !iterator_1_1.done)) return [3 /*break*/, 4];
val = iterator_1_1.value;
allVals.push(val);
if (val === 3)
return [3 /*break*/, 4];
_b.label = 3;
case 3: return [3 /*break*/, 1];
case 4: return [3 /*break*/, 11];
case 5:
e_1_1 = _b.sent();
e_1 = { error: e_1_1 };
return [3 /*break*/, 11];
case 6:
_b.trys.push([6, , 9, 10]);
if (!(iterator_1_1 && !iterator_1_1.done && (_a = iterator_1.return))) return [3 /*break*/, 8];
return [4 /*yield*/, _a.call(iterator_1)];
case 7:
_b.sent();
_b.label = 8;
case 8: return [3 /*break*/, 10];
case 9:
if (e_1) throw e_1.error;
return [7 /*endfinally*/];
case 10: return [7 /*endfinally*/];
case 11: return [2 /*return*/];
}
});
});
}
var allVals, promise;
return __generator(this, function (_a) {
switch (_a.label) {
case 0:
allVals = [];
promise = iterate(emitter);
emitter.emit(1);
emitter.emit(2);
emitter.emit(3);
expect(emitter.hasListeners()).toEqual(true);
return [4 /*yield*/, expect(promise).resolves.not.toThrow()];
case 1:
_a.sent();
expect(allVals).toEqual([1, 2, 3]);
// ensure that the iterator's return() method was called
expect(emitter.hasListeners()).toEqual(false);
return [2 /*return*/];
}
});
}); });
it('queues calls to next() such that emissions are delivered in sequence via emitted queue', function () { return __awaiter(void 0, void 0, void 0, function () {
var iterator, vals;
return __generator(this, function (_a) {
switch (_a.label) {
case 0:
iterator = emitter.asyncIterator();
// by calling emit() before next() the emitted items are queued via iterator.emitted
emitter.emit(1);
emitter.emit(2);
emitter.emit(3);
return [4 /*yield*/, Promise.all([iterator.next(), iterator.next(), iterator.next()])];
case 1:
vals = _a.sent();
expect(vals).toEqual([
{ done: false, value: 1 },
{ done: false, value: 2 },
{ done: false, value: 3 },
]);
return [2 /*return*/];
}
});
}); });
it('queues calls to next such that emissions are delivered in sequence via pending listener queue', function () { return __awaiter(void 0, void 0, void 0, function () {
var iterator, promises, _a;
return __generator(this, function (_b) {
switch (_b.label) {
case 0:
iterator = emitter.asyncIterator();
promises = [iterator.next(), iterator.next(), iterator.next()];
emitter.emit(1);
emitter.emit(2);
emitter.emit(3);
_a = expect;
return [4 /*yield*/, Promise.all(promises)];
case 1:
_a.apply(void 0, [_b.sent()]).toEqual([
{ done: false, value: 1 },
{ done: false, value: 2 },
{ done: false, value: 3 },
]);
return [2 /*return*/];
}
});
}); });
});
});
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