When it comes to Sinon not supporting the stub standalone function and imported class constructor DocumentClient, you'll need to rely on using link seams. In this case, we will utilize proxyquire for constructing our seams.
For example:
Client.ts:
import { DocumentClient } from 'aws-sdk/clients/dynamodb';
export abstract class Client {
static read = {
pk: (pk: string) => {
return {
sk: async (sk: string) => {
return await new DocumentClient()
.get({
TableName: 'TodoApp',
Key: {
PK: pk,
SK: sk,
},
})
.promise();
},
};
},
};
}
Client.test.ts:
import proxyquire from 'proxyquire';
import sinon from 'sinon';
describe('68430781', () => {
it('should pass', async () => {
const documentClientInstanceStub = {
get: sinon.stub().returnsThis(),
promise: sinon.stub().resolves('mocked data'),
};
const DocumentClientStub = sinon.stub().callsFake(() => documentClientInstanceStub);
const { Client } = proxyquire('./Client', {
'aws-sdk/clients/dynamodb': { DocumentClient: DocumentClientStub },
});
const actual = await Client.read.pk('a').sk('b');
sinon.assert.match(actual, 'mocked data');
sinon.assert.calledOnce(DocumentClientStub);
sinon.assert.calledWithExactly(documentClientInstanceStub.get, {
TableName: 'TodoApp',
Key: {
PK: 'a',
SK: 'b',
},
});
sinon.assert.calledOnce(documentClientInstanceStub.promise);
});
});
Unit test result:
68430781
✓ should pass (435ms)
1 passing (439ms)
-----------|---------|----------|---------|---------|-------------------
File | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s
-----------|---------|----------|---------|---------|-------------------
All files | 100 | 100 | 100 | 100 |
Client.ts | 100 | 100 | 100 | 100 |
-----------|---------|----------|---------|---------|-------------------