vitest/prefer-called-times

toHaveBeenCalledOnce() and toHaveBeenCalledTimes(1) assert the same thing. With toHaveBeenCalledTimes(), every call count is written the same way, and changing the expected count means changing one number. The aliases are covered too, so toBeCalledOnce() becomes toBeCalledTimes(1).

--fix rewrites the matcher.

Configure

Off by default. To turn it on:

[lint.rules]
"vitest/prefer-called-times" = "error" # or "warn"

Examples

Reported:

import { expect, test, vi } from "vitest";

test("does not retry after a success", () => {
  const request = vi.fn();
  retryFetch(request);
  expect(request).toHaveBeenCalledOnce();
});

Not reported:

import { expect, test, vi } from "vitest";

test("does not retry after a success", () => {
  const request = vi.fn();
  retryFetch(request);
  expect(request).toHaveBeenCalledTimes(1);
});

When not to use it

vitest/prefer-called-once asks for the opposite. Turn on one of the two, not both.