stub.rejects()

Causes the stub to return a Promise which rejects.

stub.rejects();

Causes the stub to return a Promise which rejects with an Error. Use this when you don't care about what the value of the error is.

import tap from "tap";
import * as sinon from "sinon";

tap.test("stub.rejects() - no arguments", async (t) => {
  const stub = sinon.stub().rejects();

  try {
    await stub();
    t.fail("should have rejected");
  } catch (error) {
    t.ok(error instanceof Error, "rejects with an Error");
    t.equal(error.message, "Error", "error message is 'Error'");
  }

  t.end();
});

stub.rejects(errorName);

Causes the stub to return a Promise which rejects with an Error, with name property set to the errorName argument and a blank message property.

import tap from "tap";
import * as sinon from "sinon";

tap.test("stub.rejects(errorName)", async (t) => {
  const stub = sinon.stub().rejects("apple pie");

  try {
    await stub();
    t.fail("should have rejected");
  } catch (error) {
    t.equal(error.name, "apple pie", "error name is set");
    t.equal(error.message, "", "error message is blank");
  }

  t.end();
});

stub.rejects(errorName, errorMessage);

Causes the stub to return a Promise which rejects with an Error, with name property set to the provided errorName and the message property set to the errorMessage argument.

import tap from "tap";
import * as sinon from "sinon";

tap.test("stub.rejects(errorName, errorMessage)", async (t) => {
  const stub = sinon.stub().rejects("some error name", "the pie is a lie");

  try {
    await stub();
    t.fail("should have rejected");
  } catch (error) {
    t.equal(error.name, "some error name", "error name is set");
    t.equal(error.message, "the pie is a lie", "error message is set");
  }

  t.end();
});

stub.rejects(error);

When called with an Error instance, it causes the stub to return a Promise which rejects with the provided error instance.

import tap from "tap";
import * as sinon from "sinon";

tap.test("stub.rejects(error)", async (t) => {
  const pieError = new RangeError("The pie is a lie");
  const stub = sinon.stub().rejects(pieError);

  try {
    await stub();
    t.fail("should have rejected");
  } catch (error) {
    t.equal(error, pieError, "rejects with the exact error instance");
  }

  t.end();
});

Note

When constructing the Promise, sinon uses the Promise.reject method.