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🐞 fix: Settle default termination in runAsync #4

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🐞 fix: Settle default termination in runAsync #4

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10 changes: 6 additions & 4 deletions src/effected.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -2623,7 +2623,7 @@ export function runAsync<E extends Effected<Effect, unknown>>(

return new Promise((resolve, reject) => {
const iterate = (...args: [] | [unknown]) => {
if (context.terminated) return context.terminatedValue;
if (context.terminated) return resolve(context.terminatedValue as never);

let done: boolean | undefined;
let value: any;
Expand All @@ -2636,7 +2636,8 @@ export function runAsync<E extends Effected<Effect, unknown>>(
}

// We use a while loop to avoid stack overflow when there are many synchronous effects
while (!done) {
// eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
while (!done && !context.terminated) {
if (!value) {
reject(
new Error(
Expand All @@ -2649,7 +2650,7 @@ export function runAsync<E extends Effected<Effect, unknown>>(
while (value instanceof Effect && typeof (value as any).defaultHandler === "function") {
value = handleEffect(context, effect.name, value, (value as any).defaultHandler).value;
// eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
if (context.terminated) return context.terminatedValue;
if (context.terminated) return resolve(context.terminatedValue as never);
}
if (value instanceof Effect) {
reject(new UnhandledEffectError(value, `Unhandled effect: ${stringifyEffect(value)}`));
Expand Down Expand Up @@ -2693,7 +2694,8 @@ export function runAsync<E extends Effected<Effect, unknown>>(
return;
}

resolve(value);
// eslint-disable-next-line @typescript-eslint/no-unnecessary-condition
resolve(context.terminated ? (context.terminatedValue as never) : value);
};

iterate();
Expand Down
124 changes: 124 additions & 0 deletions test/effected.spec.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -774,6 +774,130 @@ describe("Default handlers", () => {
expect(badProgram.runSync()).toBe("Cannot divide by zero");
});

describe("runAsync termination settlement", () => {
it.each([false, true])(
"should resolve a default termination value after an async boundary: %s",
async (afterAsync) => {
const events: string[] = [];
const stop = effect<[], never, string>()("stop", {
defaultHandler: ({ terminate }) => terminate("stopped"),
});
const program = effected(function* () {
if (afterAsync) yield* effectify(Promise.resolve());
yield* stop();
events.push("continued");
return "completed";
});

await expect(program.runAsync()).resolves.toBe("stopped");
expect(events).toEqual([]);
},
1000,
);

it("should resolve when a default generator terminates after awaiting", async () => {
const events: string[] = [];
const stop = effect<[], never, number>()("stop", {
*defaultHandler({ terminate }) {
yield* effectify(Promise.resolve());
terminate(7);
},
});
const program = effected(function* () {
yield* stop();
events.push("continued");
return 99;
});

await expect(program.runAsync()).resolves.toBe(7);
expect(events).toEqual([]);
});

it("should resolve when a default generator terminates after a synchronous effect", async () => {
const events: string[] = [];
const resume = effect<[], void>()("resume", {
defaultHandler: ({ resume }) => resume(),
});
const stop = effect<[], never, number>()("stop", {
*defaultHandler({ terminate }) {
yield* resume();
terminate(7);
},
});
const program = effected(function* () {
yield* stop();
events.push("continued");
return 99;
});

await expect(program.runAsync()).resolves.toBe(7);
expect(events).toEqual([]);
});

it("should stop parent handlers when a nested default generator terminates after awaiting", async () => {
const events: string[] = [];
const stop = effect<[], never, number>()("stop", {
*defaultHandler({ terminate }) {
yield* effectify(Promise.resolve());
terminate(7);
},
});
const outer = effect<[], number, number>()("outer", {
*defaultHandler({ resume }) {
yield* stop();
events.push("outer continued");
resume(1);
},
});
const program = effected(function* () {
yield* outer();
events.push("program continued");
return 99;
});

await expect(program.runAsync()).resolves.toBe(7);
expect(events).toEqual([]);
});

it("should resolve a default termination without a value", async () => {
const stop = effect<[], never, void>()("stop", {
defaultHandler: ({ terminate }) => terminate(),
});
const program = effected(function* () {
yield* effectify(Promise.resolve());
yield* stop();
return "completed";
});

await expect(program.runAsync()).resolves.toBeUndefined();
}, 1000);

it.each(["stopped", undefined])(
"should resolve when a default handler terminates asynchronously with %s",
async (value) => {
let terminate!: (value: string | undefined) => void;
const events: string[] = [];
const stop = effect<[], never, string | undefined>()("stop", {
defaultHandler: (context) => {
terminate = context.terminate;
},
});
const program = effected(function* () {
yield* stop();
events.push("continued");
return "completed";
});
const result = program.runAsync();

terminate(value);

await expect(result).resolves.toBe(value);
expect(events).toEqual([]);
},
1000,
);
});

it("should handle async operations in default handlers", async () => {
const fetchData = effect<[url: string], any>()("fetchData", {
defaultHandler: ({ resume }, url) => {
Expand Down
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