import { test } from "uvu";
import * as assert from "uvu/assert";
import { createEmitter } from "./emitter";
const PING = Symbol("ping");
type Events = {
message: string;
count: number;
[PING]: { ok: boolean };
};
test("emits payloads to listeners of the same event only", () => {
const emitter = createEmitter<Events>();
const received: string[] = [];
emitter.on("message", (v) => received.push(v));
emitter.on("count", (v) => received.push(`count:${v}`));
emitter.emit("message", "hello");
assert.equal(received, ["hello"]);
});
test("off unsubscribes a listener", () => {
const emitter = createEmitter<Events>();
const received: string[] = [];
const handler = (v: string) => received.push(v);
emitter.on("message", handler);
emitter.emit("message", "one");
emitter.off("message", handler);
emitter.emit("message", "two");
assert.equal(received, ["one"]);
});
test("adding the same handler twice does not duplicate calls", () => {
const emitter = createEmitter<Events>();
const received: string[] = [];
const handler = (v: string) => received.push(v);
emitter.on("message", handler);
emitter.on("message", handler);
emitter.emit("message", "hello");
assert.equal(received, ["hello"]);
});
test("supports symbol event keys", () => {
const emitter = createEmitter<Events>();
let ok = false;
emitter.on(PING, (event) => {
ok = event.ok;
});
emitter.emit(PING, { ok: true });
assert.ok(ok);
});
test("listener added during emit does not run until next emit", () => {
const emitter = createEmitter<Events>();
const calls: string[] = [];
const late = (v: string) => calls.push(`late:${v}`);
emitter.on("message", (v) => {
calls.push(`first:${v}`);
emitter.on("message", late);
});
emitter.emit("message", "one");
emitter.emit("message", "two");
assert.equal(calls, ["first:one", "first:two", "late:two"]);
});
test("listener removed during emit does not run later in same emit", () => {
const emitter = createEmitter<Events>();
const calls: string[] = [];
const second = (v: string) => calls.push(`second:${v}`);
emitter.on("message", (v) => {
calls.push(`first:${v}`);
emitter.off("message", second);
});
emitter.on("message", second);
emitter.emit("message", "one");
assert.equal(calls, ["first:one"]);
});
test.run();
