Sinon stub for node-postgres client - node.js

Question

I'm writing a Node application in TypeScript which is querying a Postgres database. In the unit tests I'm unable to mock the query-function.
My unit code looks like this:
class MyClass {
/* more stuff */
async validate(event: any): Promise<boolean> {
const client = new Client();
await client.connect();
const result = await client.query(`SELECT * FROM "user" WHERE "user_id" = '${user_id}'`);
console.log(
result
);
/* more logic */
}
}
My unit test looks like this:
describe("...", () => {
sinon.stub(pg.Client.prototype, "connect").resolves();
let stub = sinon.stub(pg.Client.prototype, "query").withArgs(
`SELECT * FROM "user" WHERE "user_id" = '1234'`,
sinon.match.any,
sinon.match.any
).resolves("asdf");
it("...", () => {
await myClassInstance.validate(event);
});
});
Not talking about the test expectations for now, what I would expect is "asdf" printed on the console. But I don't!
I've tried removing the .withArgs(...) completely and then I can see "asdf". (But obviously it doesn't help that much ...)
What I've also tried is printing stub.lastCall and I see
args: [ `SELECT * FROM "user" WHERE "user_id" = 'user_with_verified_subscription'` ]
somewhere then ...
Removing the two sinon.match.any matchers don't help either because then the TS compiler is complaining that Client.query takes 3 arguments ...
Any help is highly appreciated!
Best regards,
Max

Answer 1

Here is the unit test solution using proxyquire and sinon:
index.ts:
import { Client } from 'pg';
class MyClass {
async validate(event: any) {
const user_id = 1;
const client = new Client();
await client.connect();
const result = await client.query(`SELECT * FROM "user" WHERE "user_id" = '${user_id}'`);
console.log(result);
}
}
export default MyClass;
index.test.ts:
import sinon from 'sinon';
import proxyquire from 'proxyquire';
describe('60172091', () => {
it('should valdiate', async () => {
const pgClientStub = {
connect: sinon.stub().returnsThis(),
query: sinon
.stub()
.withArgs(`SELECT * FROM "user" WHERE "user_id" = '1'`)
.resolves('asdf'),
};
const pgStub = sinon.stub().callsFake(() => pgClientStub);
const MyClass = proxyquire('./index', {
pg: { Client: pgStub },
}).default;
const logSpy = sinon.spy(console, 'log');
const instance = new MyClass();
await instance.validate();
sinon.assert.calledOnce(pgStub);
sinon.assert.calledOnce(pgClientStub.connect);
sinon.assert.calledWithExactly(pgClientStub.query, `SELECT * FROM "user" WHERE "user_id" = '1'`);
sinon.assert.calledWithExactly(logSpy, 'asdf');
});
});
Unit test results with 100% coverage:
60172091
asdf
✓ should valdiate (2212ms)
1 passing (2s)
----------|---------|----------|---------|---------|-------------------
File | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s
----------|---------|----------|---------|---------|-------------------
All files | 100 | 100 | 100 | 100 |
index.ts | 100 | 100 | 100 | 100 |
----------|---------|----------|---------|---------|-------------------