ts-sinon-issue-198.ts

import sinon from 'sinon';
import { stubConstructor } from 'ts-sinon'

export class Calculator {
  sum(exp: string): number;
  sum(a: number, b: number): number;
  sum(...args: any): number {
    const summands = args.length === 1
      ? args[0].split('+').map((x: string) => parseFloat(x))
      : args;
    return summands.reduce((a: number, b: number) => a + b)
  }
}

describe('Calculator', () => {
  const calculator = new Calculator();
  it('adds numbers', () => {
    expect(calculator.sum(2, 3)).toBe(5)
  })
  it('adds numbers in a string', () => {
    expect(calculator.sum('2 + 3')).toBe(5)
  })
})

describe('Calculator stub', () => {
  const stub = stubConstructor(Calculator);
  beforeEach(() => stub.sum.resetHistory())

  it('can call the calculator using numbers', () => {
    stub.sum(2, 3)
    sinon.assert.calledWithMatch(
      stub.sum as unknown as sinon.SinonSpy<[a: number, b:number], number>, 2, 3
    )
  })

  it('can call the calculator using a string', () => {
    stub.sum('2 + 3')
    sinon.assert.calledWithMatch(
      stub.sum as unknown as sinon.SinonSpy<[exp: string], number>, '2 + 3'
    )
  })
})