fake pool connection using sinon js - node.js

Question

I just want to fake pool connection and
use the connection in all my unit test.
const logger = require('./logger.js');
const { Pool } = require ('pg');
const proxyquire = require('proxyquire');
const sinon = require('sinon');
var assert = sinon.assert;
const pool = new Pool ({
connectionString: process.env.HEROKU_POSTGRESQL_BLUE_URL,
ssl: {
rejectUnauthorized: false
},
//max: 500
});
async function queryWithParameter(queryToExecute,parameterReq) {
var result;
var finalResult;
try{
const client = await pool.connect();
try{
if(parameterReq == null)
result = await client.query(queryToExecute);
else
result = await client.query(queryToExecute, parameterReq);
finalResult = result.rows;
}
catch(err){
logger.error('error in queryWithParameter : ' + err);
}
finally{
client.release(true);
}
}
catch (err){
}
return finalResult;
}
module.exports = {
queryWithParameter
};
I'm supposed to use sinon.js to fake the pool connection so I cannot hit the actual DB but failed to implement it successfully.

Answer 1

I will show you how to test the test cases that "should be the correct query result".
index.js:
const { Pool } = require('pg');
const pool = new Pool({
connectionString: process.env.HEROKU_POSTGRESQL_BLUE_URL,
ssl: {
rejectUnauthorized: false,
},
});
async function queryWithParameter(queryToExecute, parameterReq) {
var result;
var finalResult;
try {
const client = await pool.connect();
try {
if (parameterReq == null) result = await client.query(queryToExecute);
else result = await client.query(queryToExecute, parameterReq);
finalResult = result.rows;
} catch (err) {
console.error('error in queryWithParameter : ' + err);
} finally {
client.release(true);
}
} catch (err) {}
return finalResult;
}
module.exports = { queryWithParameter };
index.test.js:
const sinon = require('sinon');
const proxyquire = require('proxyquire');
describe('69222273', () => {
it('should query result', async () => {
process.env.HEROKU_POSTGRESQL_BLUE_URL = 'whatever';
const res = { rows: [{ message: 'Hello world!' }] };
const clientStub = { query: sinon.stub().resolves(res), release: sinon.stub() };
const poolStub = { connect: sinon.stub().resolves(clientStub) };
const pgStub = { Pool: sinon.stub().returns(poolStub) };
const { queryWithParameter } = proxyquire('./', {
pg: pgStub,
});
const actual = await queryWithParameter('SELECT $1::text as message', ['Hello world!']);
sinon.assert.calledWithExactly(pgStub.Pool, {
connectionString: 'whatever',
ssl: {
rejectUnauthorized: false,
},
});
sinon.assert.calledOnce(poolStub.connect);
sinon.assert.calledWithExactly(clientStub.query, 'SELECT $1::text as message', ['Hello world!']);
sinon.assert.match(actual, [{ message: 'Hello world!' }]);
sinon.assert.calledWithExactly(clientStub.release, true);
});
});
test result:
69222273
✓ should query result (1350ms)
1 passing (1s)
----------|---------|----------|---------|---------|-------------------
File | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s
----------|---------|----------|---------|---------|-------------------
All files | 84.62 | 50 | 100 | 91.67 |
index.js | 84.62 | 50 | 100 | 91.67 | 22
----------|---------|----------|---------|---------|-------------------