How to mock stats method in elasticsearch?

Question

I want to query stats of elasticsearch using nodeJs.

Here is my source code

const {Client}  = require('@elastic/elasticsearch');
client = new Client({
Connection:'appropriate aws connection',
node:'some url',
agent:{
  keepalive:,
  maxsocket:,
  maxfreesocket:
}
})

const stats = await client.nodes.stats();

console.log(stats);

// some operation on stats

How do i mock this elasticsearch method?
I have tried following but it is unable to mock the stats().

 let sandbox = sinon.createSandbox();
 before(()=>{
   sandbox.stub(Client.prototype,'nodes').get(()=>{
      stats: ()=>{
       return dymmydata;
     }
//where dummydata is already hardcoded
   })
 })

Where am I going wrong here?

Answer 1

Let's see how the nodes API is defined. See /v8.8.1/src/api/index.ts#L401, you will find the nodes API is defined by Object.defineProperties with a getter function.

Object.defineProperties(API.prototype, {
  // ...
  nodes: {
    get () { return this[kNodes] === null ? (this[kNodes] = new NodesApi(this.transport)) : this[kNodes] }
  }
  // ...
}

We should use stub.get(getterFn) API to replace a new getter for this stub.

E.g.

index.js:

const { Client } = require('@elastic/elasticsearch');

const client = new Client({
    node: 'http://localhost:9200',
});

export function main() {
    return client.nodes.stats();
}

index.test.js:

const sinon = require('sinon');
const { Client } = require('@elastic/elasticsearch');

describe('76653113', () => {
    it('should pass', async () => {
        const nodesApiMock = {
            stats: sinon.stub().resolves('ok'),
        };
        sinon.stub(Client.prototype, 'nodes').get(() => nodesApiMock);
        const { main } = require('./');
        const actual = await main();
        sinon.assert.match(actual, 'ok');
        sinon.assert.calledOnce(nodesApiMock.stats);
    });
});