jest/prefer-to-have-been-called-times

Require toHaveBeenCalledTimes() instead of checking the length of mock.calls

fixable

When expect(save.mock.calls).toHaveLength(2) fails, the message is about the length of an array. expect(save).toHaveBeenCalledTimes(2) says what the test means, and its failure message shows the expected and received number of calls.

--fix rewrites the assertion.

Configure#

Off by default. To turn it on:

bunfig.toml
[lint.rules]
"jest/prefer-to-have-been-called-times" = "error" # or "warn"

Examples#

example.ts1 problem
import { expect, jest, test } from "@jest/globals";

test("saves each item once", () => {
  const save = jest.fn();
  saveAll(["a", "b"], save);
  expect(save.mock.calls).toHaveLength(2);
});
example.tsNo problems
import { expect, jest, test } from "@jest/globals";

test("saves each item once", () => {
  const save = jest.fn();
  saveAll(["a", "b"], save);
  expect(save).toHaveBeenCalledTimes(2);
  expect(save.mock.calls[0]).toHaveLength(1); // the arguments of the first call
});