A wrapper for chai that adds a count of the number times expect is called.

chaiCounter.js

import { expect as chai } from 'chai';

let expected = null;
let actual = 0;

export default {

  expect(target) {
    actual++;
    return chai(target);
  },

  expectCount(count) {
    expected = count;
  },

  reset() {
    expected = null;
    actual = 0;
  },

  check() {
    if (this.currentTest.state === 'failed' || expected === null || expected === actual) { return; }
    let err = new Error(`expected ${expected} assertions, got ${actual}`);
    this.currentTest.emit('error', err);
  }
}

exampleTest.js

import counter, { expect, expectCount } from './helpers/chaiCounter';

beforeEach(counter.reset);
afterEach(counter.check);

describe('something', function () {

  it('should work', function () {
    // we expect two asserts to be called, if no asserts are made then the test should fail
    expectCount(2);

    const state = {
      set(path, value) {
        expect(path).to.equal('someKey');
        expect(value).to.equal('someValue');
      }
    };

    setState(state);
  });

});