How to stub oracledb with sinon? - node.js

Question

Here is my function which will return a promise once it gets data from oracle database:
const getDataFromOracleDB = (filter, query) =>
new Promise(async (resolve, reject) => {
let conn;
try {
conn = await oracledb.getConnection(dbConfig);
const result = await conn.execute(query, [filter]);
const { rows } = result;
...
catch (err) {
...
}
};
As the unit test, I want to stub conn.execute, but have no idea how to do that. I've treid:
const stub = sinon.stub(conn, 'execute').returns([1, 2, 3]);
But got:
TypeError: Cannot stub non-existent own property execute
Any suggestions?

Answer 1

I can't replicate the error with the code you supplied, but perhaps this quick mockup will help:
const chai = require('chai');
const sinon = require('sinon');
const oracledb = require('oracledb');
const config = require('./dbConfig.js');
const expect = chai.expect;
sinon.stub(oracledb, 'getConnection').resolves({
execute: function() {},
close: function() {}
});
describe('Parent', () => {
describe('child', () => {
it('should work', async (done) => {
let conn;
try {
conn = await oracledb.getConnection(config);
sinon.stub(conn, 'execute').resolves({
rows: [[2]]
});
let result = await conn.execute(
'select 1 from dual'
);
expect(result.rows[0][0]).to.equal(2);
done();
} catch (err) {
done(err);
} finally {
if (conn) {
try {
await conn.close();
} catch (err) {
console.error(err);
}
}
}
});
});
});
The query would normally return a value of 1, but this returns 2 and passes.