# Unit tests with AWS CDK

Lately, I have been using the AWS CDK a lot to set up infrastructure on AWS, and the fact that they have integrated solutions to unit test the code is really great.

I will show how to use the CDK assertions (aws-cdk-lib/assertions) library to write unit tests about your stacks. The library (aws-cdk-lib/assertions) contains several helper functions for writing unit and integration tests.

### Create a project


```
mkdir unitTestCdk
cd unitTestCdk
cdk init app --language typescript
yarn add @aws-cdk/assert
``` 

The command generates an empty stack.

Go to lib/unit_test_cdk-stack.ts


```
import { Stack, StackProps } from 'aws-cdk-lib';
import { Construct } from 'constructs';

export class UnitTestCdkStack extends Stack {
  constructor(scope: Construct, id: string, props?: StackProps) {
    super(scope, id, props);

    // The code that defines your stack goes here
       👇👇👇👇👇👇👇👇

  }
}
``` 

Let's write a test for that.

Go to test/unit_test_cdk.test.ts, you will already have the structure to write your first test.
Let's write our test : 


```
import * as cdk from 'aws-cdk-lib';
import '@aws-cdk/assert/jest';
import * as UnitTestCdk from '../lib/unit_test_cdk-stack';

test('Empty stack', () => {
    const app = new cdk.App();

    const stack = new UnitTestCdk.UnitTestCdkStack(app, 'MyTestStack');

    expect(stack).not.toHaveResource('AWS::SQS::Queue');
});

``` 

Let's run our test


```
yarn test

$ jest
 PASS  test/unit_test_cdk.test.ts (7.442 s)
  ✓ Empty stack (25 ms)

Test Suites: 1 passed, 1 total
Tests:       1 passed, 1 total
Snapshots:   0 total
Time:        7.488 s
Ran all test suites.
✨  Done in 8.23s.

```

Great ! Now let's add a resource , and update our test

### With a SQS queue


```
import { Stack, StackProps } from 'aws-cdk-lib';
import { Construct } from 'constructs';
import * as sqs from 'aws-cdk-lib/aws-sqs';

export class UnitTestCdkStack extends Stack {
  constructor(scope: Construct, id: string, props?: StackProps) {
    super(scope, id, props);

    // The code that defines your stack goes here

    // example resource
    const queue = new sqs.Queue(this, 'UnitTestCdkQueue', {
      queueName: "sqs-test"
    });
  }
}
```

Let's update our test now


```
import * as cdk from 'aws-cdk-lib';
import '@aws-cdk/assert/jest';
import * as UnitTestCdk from '../lib/unit_test_cdk-stack';

test('stack with SQS queue', () => {
    const app = new cdk.App();

    const stack = new UnitTestCdk.UnitTestCdkStack(app, 'MyTestStack');

    expect(stack).toHaveResource('AWS::SQS::Queue');
});
``` 

And run the test 


```
yarn test

 PASS  test/unit_test_cdk.test.ts (10.276 s)
  ✓ stack with SQS queue (29 ms)

Test Suites: 1 passed, 1 total
Tests:       1 passed, 1 total
Snapshots:   0 total
Time:        10.346 s
Ran all test suites.
✨  Done in 11.81s.
``` 

We can even test check the queue name : 

```
import * as cdk from 'aws-cdk-lib';
import '@aws-cdk/assert/jest';
import * as UnitTestCdk from '../lib/unit_test_cdk-stack';

test('stack with SQS queue', () => {
    const app = new cdk.App();

    const stack = new UnitTestCdk.UnitTestCdkStack(app, 'MyTestStack');

    expect(stack).toHaveResource('AWS::SQS::Queue', {
        QueueName: 'sqs-test'
     });
});

``` 

You can look further in the  [AWS Documentation](https://docs.aws.amazon.com/cdk/v2/guide/testing.html)  to find helpers to test your stack the way you need it.

### Conclusion

Now, you know how to unit test your infrastructure created with AWS CDK ! 

If you have any questions, feel free to ask in the comments, i'll do my best to answer ! 

See you next in the next one ! 🤖