I'm trying to use spyOn in Jest to mock an AWS SNS publish call. I'm not well versed in AWS's ecosystem, nor am I super experienced with writing Jest tests, so I'm a bit stuck. In the following test code, when spyOn is called for the DynamoDB put method I receive no errors, but when it's called for the SNS publish method, I receive the error that follows. Most of this code was written by someone else, and I'm attempting to follow the same templating for the publish mock.

const lambda = require('../../../src/handlers/sign-up.js');

const dynamodb = require('aws-sdk/clients/dynamodb'); 
const AWS = require("aws-sdk");
AWS.config.update({region: 'us-east-1'})
const sns = new AWS.SNS();

const allowOrigin = process.env.ALLOW_ORIGIN

describe('Test signUpHandler', function () {
    let putSpy; 
    let publishSpy;

    beforeAll(() => { 
        putSpy = jest.spyOn(dynamodb.DocumentClient.prototype, 'put'); 
        publishSpy = jest.spyOn(sns.prototype, 'publish')
    }); 
 

    afterAll(() => { 
        publishSpy.mockRestore();
        putSpy.mockRestore(); 
    });
 

    it('should add email to the table', async () => {
        const returnedItem = { email: 'test@example.com' };
 
        putSpy.mockReturnValue({ 
            promise: () => Promise.resolve(returnedItem) 
        }); 
 
        const event = { 
            httpMethod: 'POST', 
            headers: {
                origin: allowOrigin
            },
            body: '{"email": "test@example.com"}'
        }; 
     
        const result = await lambda.signUpHandler(event);
        const expectedResult = { 
            statusCode: 200,
            headers: {"Access-Control-Allow-Origin": allowOrigin},
            body: JSON.stringify({"success": true})
        }; 

        expect(result).toEqual(expectedResult); 
    }); 
}); 

When I run the test, I get this error:

Cannot spyOn on a primitive value; undefined given

      20 |         putSpy = jest.spyOn(dynamodb.DocumentClient.prototype, 'put'); 
    > 21 |         publishSpy = jest.spyOn(sns.prototype, 'publish')
         |                           ^
      22 |     }); 

Am I approaching this wrong? Any help would be greatly appreciated.