 Resources from Tomasz Łakomy in 2021

Fast, easy and reliable testing for anything that runs in a browser.

cypress

In this quick lesson we're going to learn how we can use `type` and `clear` commands from cypress API in order to test a search input and what kind of tricks we can use in order to make our tests less brittle and more resilient. 

Test a search input in an e2e test with cypress

"You've all heard about TDD - now it's time for Cypress Driven Development"

Jokes aside, it can be sometimes beneficial to implement a cypress tests for a given feature before we start implementing it. 

Using a cypress test, we can express the functionality we'd like to have in our app and after we implement it - we'll know if it works exactly as intended. 

In this lesson we're implement a 'results not found' screen in an Emoji Search app by writing a cypress test first, and implementation later. Cypress allows us to have a very fast feedback loop that makes implementing features like this much simpler.

Use "Cypress Driven Development" in order to add a feature to a React app

Our tests should not be brittle and break just before the data returned from the API changed slightly. As an example - imagine testing Twitter with their ever-changing feed.

When writing e2e tests it's important to have a known state of the app at the beginning of each test so that potential failures depend specifically on the thing we're trying to test.

In this lesson we're going to learn how to use cy.server() and cy.route() to control API response in a cypress test.

Use cy.server() and cy.route() to control API response in a cypress test

Most of the time the communication between backend and frontend works seamlessly.

Until it doesn't.

When our e2e tests start to fail because there's an issue with an API response, it's important to know how to debug it.

In this lesson we're going to learn how to get insights about a network request and its response using the cypress UI.

Use cypress UI in order to debug an API response

Developers need to focus to do their job right.

Cypress tests are no different - sometimes we have a large suite of cypress tests but unfortunately one of them is failing :(

We're lucky that it's only one, but when we dig in and debug, we find ourselves being slowed done because we need to wait for all those passing tests to finish in order to focus on the failing one.

In this quick lesson we're going to learn how to use `.only` in cypress suite in order to run only a single test that we've chosen.

Use cy.only in order to run only a single test in a cypress test suite

Some of our tests in a cypress suite can cause problems or have performance issues that we need to take care of.

Sometimes it's even necessary to skip one of the tests because our CI/CD pipeline is failing because of a randomly failing test - at this time we should spend time to improve that test as soon as we can.

Of course we could comment the test out or remove it from the codebase entirely, but a better solution is to use `.skip` in order to (temporarily) skip a cypress test - and that's exactly what we're going to learn in this quick lesson.

Use cy.skip in order to skip a test in a cypress suite

Long time ago, frontend developers (or as we called them back then - webmasters) could get away with supporting only one or two resolutions.

Those days are long gone.

In this lesson we're going to learn how to change a viewport width and height in a cypress test in order to ensure that our app works as intended on a given resolution.

Change a viewport width and height in a cypress test

Amazon Web Services (AWS) is a powerful expansive cloud infrastructure platform for building modern web applications.

AWS provides services for data, presentation, authentication, security, video encoding, and much more. Offering over 175 fully-featured services from data centers globally, AWS powers a large percentage of the internet.

Creating resources in AWS using the AWS Console gets tricky after a while - after using the UI in order to build an architecture of our app, it can be really complicated to replicate that same structure in another region for example. There's also another issue - there's no clear place where we can see what our stack looks like.

Serverless Framework is a way of addressing that - it simplifies our workflow of building serverless applications in the Cloud.

To quote the Serverless Framework docs:

>The Serverless Framework gives you everything you need to develop, deploy, monitor and secure serverless applications on any cloud.

In this quick lesson we're going to learn how to install the Serverless Framework, how to create a new project and lastly we'll deploy a Lambda function to AWS Cloud.

Create a simple serverless stack from scratch with Serverless Framework

In order to use various AWS solutions (such as AWS SAM or AWS CDK) we need to be able to connect our local environment to "the cloud".

In this quick lesson we're going to learn how to:

- create a brand new user for our AWS account
- create a new IAM Group with AdministratorAccess policy
- add a user to a newly created group
- configure AWS CLI (if you don't have AWS CLI installed, please follow [this](https://docs.aws.amazon.com/cli/latest/userguide/install-cliv2.html) guide)
- delete an IAM User

Create an admin user with IAM and configure AWS CLI to enable programmatic access to AWS

All amazing projects have to start somewhere and AWS CDK is no exception.

In this quick lesson we're going to learn how to install AWS CDK command line interface with `npm` as well as how to use `cdk init` in order to create our very first CDK project 🥳

Install AWS Cloud Development Kit (CDK) and create a new project

Now that our initial AWS CDK project has been created, it's time to deploy it!

In this quick lesson we're going to learn:
- where do we define an AWS CDK stack
- what is a CDK construct (you can read more about CDK construct [here](https://docs.aws.amazon.com/cdk/latest/guide/constructs.html) )
- how to use `cdk diff` command in order to see the difference between our currently deployed stack and the stack we're about to deploy
- how to use `cdk deploy` in order to deploy a CDK stack to AWS

Build and deploy a sample AWS Cloud Development Kit stack to AWS

Now that our initial stack has been deployed it's time to dig into AWS Console to see what exactly did we deploy.

Cloud Development Kit is built on top of CloudFormation which is an AWS service that allows you to describe a stack in AWS using a static file (either YAML or JSON).

In essence - it's going to convert our code written in TypeScript, to JavaScript, which will be then converted to CloudFormation and CloudFormation will be used to deploy our infrastructure.

Sounds complicated, right? Luckily CDK abstracts a lot of things away from us, so we get to focus on solving our problems instead of writing YAML by hand.

In this lesson we're going to learn how to review an AWS CDK stack deployment in CloudFormation console.

Review an AWS CloudFormation stack deployed with AWS CDK

In this quick lesson we're going to clear out the SQS Queue and SNS Topic that was created for us when we created a CDK app with `cdk init` in order for us to be able to start building our app from scratch.

Clear an initial AWS CDK stack to start building an app from scratch

It's time to start building our serverless backend!

In this quick lesson we're going to use the `lambda.Function` construct imported from `@aws-cdk/aws-lambda` in order to build and deploy a 'Hello World!' AWS Lambda function.

You can find out more about what kind of constructs are available in AWS CDK construct library [here](https://docs.aws.amazon.com/cdk/api/latest/docs/aws-lambda-readme.html)

Create and deploy a lambda function with AWS CDK

In the previous lesson we've managed to successfully create and deploy an AWS Lambda function.

Before we progress further, in this lesson we're going to quickly take a look at AWS Console in order to understand where exactly can we find the stack that we've deployed and also execute the lambda function using a test event to make sure that it's working fine.

Review and execute a lambda function deployed with CDK in AWS Console

Every resource we deploy to AWS with CDK has some default values configured for us so that we don't have to configure everything ourselves.

This comes in handy because it allows us to focus on building our infrastructure and solving our problems instead of configuring everything.

With that being said - CDK allows us to configure various properties of our resources! In this quick lesson we're going to learn how to configure the memory size and timeout of an AWS Lambda function.

Change the properties of a lambda function deployed with AWS CDK

Serverless technologies like AWS Lambda allow us to build our applications out of small, independent functions that can be called based on events such as an API call.

By default, it's not possible to call a lambda function from the Internet - it's safely stored within AWS cloud, following the principle of least privilege.

In order to create a REST API to call a lambda function we need to use [API Gateway](https://aws.amazon.com/api-gateway/). Luckily, with AWS CDK, we can create a `LambdaRestApi` in 3 lines of code and this is exactly what we're going to learn in this quick lesson!



Attach an API Gateway to a lambda function deployed with AWS CDK

Environment variables are really useful in programming - they allow us to avoid hardcoding secrets (such as API keys) in our code with added bonus of using different values depending on the environment (hence the name!).

In this quick lesson we're going to learn how to pass environment variables to an AWS Lambda function deployed with Cloud Development Kit (in a single line of code!)

Pass environment variables to a lambda function deployed with AWS CDK

Building and debugging lambda functions can be tricky.

Once a function becomes non-trivial, the cycle of:

- build
- deploy to AWS
- test
- fix
- repeat

wastes *a lot* of time. Luckily, there's an alternative.

In this quick lesson we're going to learn how to use AWS Serverless Application Model (SAM) command line interface in order to execute a lambda function built with CDK locally.

This lesson is a bit optional because it touches a topic that is not going to be relevant for the rest of this course (although running lambda functions locally is *really* useful).

If you'd like to learn more about AWS SAM, there's a whole collection about it: [Build serverless applications with AWS Serverless Application Model (AWS SAM)
](https://egghead.io/playlists/learn-aws-serverless-application-model-aws-sam-framework-from-scratch-baf9)

Run lambda functions built with CDK locally using AWS SAM

Lambdas and API Gateways are not the only type of AWS resource we can deploy to AWS cloud using CDK. In fact - nearly every resource that is deployable (is that a word?) with CloudFormation, can also be deployed with AWS CDK.

One of the most popular services on AWS is Amazon S3, which stands for Simple Storage Service.

As the name suggests - it's nothing but simple (in my humble opinion), luckily creating a new S3 bucket and deploying it to the cloud using CDK is relatively straightforward.

Files on S3 are stored in things called "buckets", which are unlimited in size and each bucket has a globally unique name.

In this quick lesson we're going to create and deploy a brand new S3 bucket to AWS with CDK

Create and deploy an S3 bucket with AWS CDK

Files uploaded to an S3 bucket are not accessible by default from the Internet.

Which makes sense - by default they should be secure, but since we'd like to host a logo file to be displayed in our app, we need to make the bucket public.

Luckily, with CDK we need to literally change a single line of code - in this quick lesson we're going to learn how to make the contents of an S3 bucket public.

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