#prefer-called-exactly-once-with

#Configuration

import { defineConfig, rstestPlugin } from '@rslint/core';

export default defineConfig([
  rstestPlugin.configs.recommended,
  {
    rules: {
      'rstest/prefer-called-exactly-once-with': 'error',
    },
  },
]);

#Rule Details

Prefers one exact mock assertion over separate call-count and argument assertions. The combined matcher states the complete expectation in one place.

Chai-style calledOnce and calledWith assertions are supported too.

#Incorrect

expect(handler).toHaveBeenCalledOnce();
expect(handler).toHaveBeenCalledWith('ready');

#Correct

expect(handler).toHaveBeenCalledExactlyOnceWith('ready');

#Autofix

Merges the pair into the combined matcher, keeping the argument-side assertion and deleting the call-count one. The pair is reported without a fix when the subject cannot be evaluated once instead of twice, as in expect(getMock()), or when one of the two chains carries further assertions that deleting the statement would drop.