#prefer-to-have-been-called

#Configuration

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

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

#Rule Details

Use toHaveBeenCalled() instead of comparing a mock's call count with zero. Write .not.toHaveBeenCalled() to assert that a mock was never called, or .toHaveBeenCalled() to assert that it was called at least once. These matchers express the intent directly and provide clearer failure messages. See the Rstest mock assertions.

This rule checks toHaveBeenCalledTimes(0) and its toBeCalledTimes(0) alias, including negated assertions, dot and literal bracket access, soft, poll, and resolves or rejects chains. It recognizes global expect, named and renamed imports, namespace imports, CommonJS bindings from @rstest/core, rstack/test, and @rstest/playwright, import.meta.rstest, and test-context expect. Bindings that are reassigned anywhere in the file are not checked. It does not require type information.

Parentheses and as or angle-bracket type assertions around the zero are accepted. Variables, computed expressions, unary +0 or -0, and satisfies or non-null wrappers are not checked. Type assertions and non-null wrappers around the assertion receiver also stop recognition. Chai language chains and individual matching calls within multi-assertion chains are checked, but Chai's callCount(0) and property assertions are not rewritten. Static expect methods, expect.element, dynamic matcher names, and repeated not, resolves, or rejects modifiers are not checked.

#Incorrect

import { expect, rs, test } from '@rstest/core';

test('notifies only subscribed listeners', () => {
  const subscribed = rs.fn();
  const unsubscribed = rs.fn();
  subscribed('ready');

  expect(unsubscribed).toHaveBeenCalledTimes(0);
  expect(subscribed).not.toHaveBeenCalledTimes(0);
});

#Correct

import { expect, rs, test } from '@rstest/core';

test('notifies only subscribed listeners', () => {
  const subscribed = rs.fn();
  const unsubscribed = rs.fn();
  subscribed('ready');

  expect(unsubscribed).not.toHaveBeenCalled();
  expect(subscribed).toHaveBeenCalled();
});

#Autofix

The fix replaces the count matcher with toHaveBeenCalled, removes the zero argument and any explicit type arguments, and adds or removes .not. It preserves promise modifiers, accessor quotes, and optional chaining.

expect.poll assertions are reported without a fix because the callback can observe the assertion's negation state through this.

For other assertion factories, only standalone assertion statements are automatically fixed; parentheses and await around the assertion are allowed. Assertions used in assignments, return values (including concise arrow functions), arguments, or other expressions are reported without a fix because the returned assertion object can retain .not when reused.

Assertions with extra arguments, comments inside the removed argument or type-argument list, multiple matchers in one chain, or property accesses or calls following the matcher are also reported without a fix. This avoids deleting argument evaluation or comments and changing the assertion state observed later in a chain.