Tag: mock

Mocking AWS SSM with Jest and TypeScript

March 29th, 2023

Reading Time: < 1 minutes

Let’s say you have this code that uses SSM:

import { SSM } from 'aws-sdk';

const getSecureParameter = async (paramName: string): Promise<string | undefined> => {
    if (paramName.startsWith('/wrong')) throw new Error('wrong parameter');
    const ssm = new SSM();
    const secret = await ssm
        .getParameter({
            Name: paramName,
            WithDecryption: true,
        })
        .promise();
    return secret.Parameter ? secret.Parameter.Value : undefined;
};

export const getParam1 = () => getSecureParameter('/ssm/param/name/example');
export const getParam2 = () => getSecureParameter('/wrong/param');
export const getParam3 = () => getSecureParameter('/not/found/param');

To mock AWS SSM with Jest and TypeScript, you can use the AWS SDK’s mock implementation. Here’s how you can set it up:

import AWS from 'aws-sdk';
import { getParam1, getParam2, getParam3 } from '../mock';

jest.mock('aws-sdk');

const mockAws = AWS as jest.Mocked<any>;

const ssmMock = {
    getParameter: (options: AWS.SSM.Types.GetParameterRequest) => {
        return {
            promise: () => {
                switch (options.Name) {
                    case '/not/found/param': {
                        return Promise.reject(new Error('some error'));
                        break;
                    }
                    default: {
                        return Promise.resolve({
                            Parameter: {
                                Value: `mocked secret for ${options.Name}`,
                            },
                        });
                    }
                }
            },
        };
    },
};

describe('AWS SSM mock example tests', () => {
    beforeAll(() => {
        mockAws.SSM.mockImplementation(jest.fn().mockImplementation(() => ssmMock));
    });

    beforeEach(() => {
        //
    });

    it('should success when...', async () => {
        // example
        const result = await getParam1();
        expect(result).toBe('mocked secret for /ssm/param/name/example');
    });

    it('should fail due to some reason...', async () => {
        // example:
        await expect(getParam2()).rejects.toThrow(new Error('wrong parameter'));
    });

    it('should fail due to another reason...', async () => {
        // example:
        await expect(getParam3()).rejects.toThrow(new Error('some error'));
    });
});

How to Mock Axios with Jest

March 28th, 2023
Reading Time: < 1 minutes
Axios is a popular JavaScript library used for making HTTP requests in web applications. Jest, on the other hand, is a JavaScript testing framework that comes with a built-in mocking feature that makes it easy to mock Axios in your tests. In this blog post, we’ll explore how to mock Axios with Jest, step by step.

To mock Axios with Jest, you can use the Jest mock function to replace the actual Axios library with a mock implementation.

Here is an example of how to mock Axios with Jest:
```
// Import the Axios library
import axios from 'axios';

// Mock the Axios library with Jest
jest.mock('axios');

// Define the mock response data
const mockResponse = {
  data: {
    id: 1,
    name: 'John Doe',
  },
};

// Set up the mock implementation for Axios
axios.get.mockImplementation(() => Promise.resolve(mockResponse));

// Call the Axios method in your test
axios.get('/users/1').then((response) => {
  expect(response.data).toEqual(mockResponse.data);
});
```
In the example above, we first import the Axios library and then mock it with Jest. We then define a mock response data object and set up the mock implementation for the Axios get method to return a Promise that resolves with the mock response data.

Finally, we call the Axios get method in our test and use Jest’s expect function to assert that the response data matches the mock response data.

Note that you may need to modify this example to suit your specific use case, depending on the methods you are calling and the data you are expecting in response.
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Tag: mock

Mocking AWS SSM with Jest and TypeScript

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How to Mock Axios with Jest

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