stub.callsArg(index)
Causes the stub to call the argument at the provided index as a callback function.
js
import tap from "tap";
import * as sinon from "sinon";
tap.test("stub.callsArg - basic usage", (t) => {
const stub = sinon.stub().callsArg(0);
const callback = sinon.fake();
stub(callback);
t.ok(callback.called, "callback was called");
t.end();
});
tap.test("stub.callsArg - errors", (t) => {
const stub = sinon.stub().callsArg(0);
t.throws(
() => stub(),
/callsArg failed: 1 arguments required but only 0 present/,
"throws when no arguments provided"
);
t.throws(
() => stub("definitely not a function"),
/argument at index 0 is not a function/,
"throws when argument is not a function"
);
t.end();
});Errors
When the argument at the provided index is not available or is not a function, an Error will be thrown.