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stub.yieldsToOnAsync(property, context, [arg1, arg2, ...]) ​

Causes the spy to invoke a callback passed as a property of an object to the spy.

yieldsToOnAsync grabs the first matching argument, finds the callback and calls it, passing the this context and any (optional) arguments, asynchronously.

js
import t from "tap";
import sinon from "sinon";

t.test(
  "stub.yieldsToOnAsync invokes callback asynchronously with context and args",
  async (t) => {
    const clock = sinon.useFakeTimers();

    const obj = {
      setItem: sinon.fake(function (newItem) {
        this.item = newItem;
      })
    };
    const obj2 = {
      item: "Apple Pie"
    };

    const stub = sinon
      .stub()
      .yieldsToOnAsync("setItem", obj2, "Sweet potato pie");

    stub(obj);

    // Verify initial state (callback not yet invoked)
    t.notOk(obj.setItem.called, "setItem should not be called yet");
    t.equal(
      obj2.item,
      "Apple Pie",
      "item should still be 'Apple Pie' initially"
    );

    // Advance time to trigger async callback
    await clock.tickAsync(1);

    // Verify callback was invoked asynchronously with correct context and arguments
    t.ok(obj.setItem.calledOnce, "setItem should be called once");
    t.ok(
      obj.setItem.calledOn(obj2),
      "setItem should be called with obj2 as this context"
    );
    t.ok(
      obj.setItem.calledWith("Sweet potato pie"),
      "setItem should be called with 'Sweet potato pie'"
    );
    t.equal(
      obj2.item,
      "Sweet potato pie",
      "item should be updated to 'Sweet potato pie'"
    );

    clock.restore();
    t.end();
  }
);

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