I'm trying to write out a unit test that stubs the getSignedUrl function from the @aws-sdk/s3-request-presigner package, however when I try stub out the function with sinon, I receive the error:
- TypeError: Descriptor for property getSignedUrl is non-configurable and non-writable
const s3RequestSigner = require("@aws-sdk/s3-request-presigner");
const expect = require('chai').expect;
const sinon = require('sinon')
....
it('should throw an error when getSignedUrl rejects', async function() {
const sandbox = sinon.createSandbox();
sandbox.stub(s3RequestSigner, "getSignedUrl").rejects("fakeUrl");
sandbox.restore();
})
I'm using node.js 16 and writing javascript rather than typescript. Is there a way to mock out my function, i'm struggling to write my tests otherwise?
So I won't make this the official answer, unless there are no better solutions, but this is what my research has brought about a solution.
The issue is related to this: https://github.com/sinonjs/sinon/issues/2377
Where sinon will throw an error when the Object.descriptor is non-configurable.
There is no obvious way around that currently, that I can find. The way to solve it is to use proxyquire:
const sinon = require('sinon')
const proxyquire = require('proxyquire')
...
it('should throw an error when getSignedUrl rejects', async function() {
const fakeurl = 'hello world'
const fakeURL = sinon.stub().resolves(fakeurl)
const handler = proxyquire(
'../../handlers/presigned_url',
{
'@aws-sdk/s3-request-presigner': {
'getSignedUrl': async () => {
return fakeURL()
}
}
}
)
This will then resolve with whatever you want fakeurl to be.