sinon_match_generator.js

const input = {
  x: 'hello world',
  y: 2,
  f: true,
  z: {
    a: [1,2,3],
    b: new Set([1,2,3]),
    c: new Map([['hello', 'world']]),
    d: null,
    e: undefined
  },
  g: () => {}
}

const STRING_TYPE = 'string';
const NUMBER_TYPE = 'number';
const BOOLEAN_TYPE = 'boolean';
const FALSY_TYPE = 'falsy';
const OBJECT_TYPE = 'object';
const FUNCTION_TYPE = 'function';

const type = {
  [STRING_TYPE]: 'sinon.match.string',
  [NUMBER_TYPE]: 'sinon.match.number',
  [FALSY_TYPE]: 'sinon.match.falsy',
  [BOOLEAN_TYPE]: 'sinon.match.bool',
  'array': 'sinon.match.array',
  'function': 'sinon.match.func',
  'map': 'sinon.match.map',
  'set': 'sinon.match.set'
}


function gen(arg) {
  const keys = Object.keys(arg);
  if (!keys && !keys.length) {
    return {};
  }
  return keys.reduce((acc, val) => {
    if (typeof arg[val] === STRING_TYPE) {
      acc[val] = type[STRING_TYPE]
      return acc;
    }
    if (typeof arg[val] === NUMBER_TYPE) {
      acc[val] = type[NUMBER_TYPE]
      return acc;
    }
    if (typeof arg[val] === BOOLEAN_TYPE) {
      acc[val] = type[BOOLEAN_TYPE]
      return acc;
    }
    if (arg[val] instanceof Map) {
      acc[val] = type['map']
      return acc;
    }
    if (arg[val] instanceof Set) {
      acc[val] = type['set']
      return acc;
    }
    if (arg[val] === null || arg[val] === undefined) {
      acc[val] = type[FALSY_TYPE]
      return acc;
    }
    if (typeof arg[val] === OBJECT_TYPE && Array.isArray(arg[val])) {
      acc[val] = type['array']
      return acc;
    }
    if (typeof arg[val] === OBJECT_TYPE && arg[val] !== null) {
      acc[val] = gen(arg[val])
      return acc;
    }
    if (typeof arg[val] === FUNCTION_TYPE) {
      acc[val] = type[FUNCTION_TYPE]
      return acc;
    }
    return acc;
  }, {});
}


const x = gen(input);

console.log(x)

The output object values will be strings so a quick find and replace of all single quotes and then deleting of those single quotes will get a working object to sinon.assert against,

// Sample Output

{ x: 'sinon.match.string',
  y: 'sinon.match.number',
  f: 'sinon.match.bool',
  z:
   { a: 'sinon.match.array',
     b: 'sinon.match.set',
     c: 'sinon.match.map',
     d: 'sinon.match.falsy',
     e: 'sinon.match.falsy' },
  g: 'sinon.match.func' }

const sinon = require('sinon');

function fetchDataToSend() {
 return {
  x: 'hello world',
  y: 2,
  f: true,
  z: {
    a: [1,2,3],
    b: new Set([1,2,3]),
    c: new Map([['hello', 'world']]),
    d: null,
    e: undefined
  },
  g: () => {}
}
}

// Helper to keep test clean & avoid repeats
function assertShapeMatches(input) {
    sinon.assert.match(input, { 
  x: sinon.match.string,
  y: sinon.match.number,
  f: sinon.match.bool,
  z:
   { a: sinon.match.array,
     b: sinon.match.set,
     c: sinon.match.map,
     d: sinon.match.falsy,
     e: sinon.match.falsy
   },
  g: sinon.match.func
 });
}

// Sample Test
describe('some outgoing http request',()=> {
 it('should match the expected request to be sent', () => {
   const input = fetchDataToSend();
   assertShapeMatches(input);
 });
})