CI for Node

[rjtshrm]

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[github-learning-lab]

The title of this pull request isn't what I expected!

To rename your pull request:

1. Click on Edit next to the pull request's title.
2. The title will turn to a text field, CI for Node in the title field.
3. Click Save.

I'll respond when I detect this pull request has been renamed.

[github-learning-lab]

Templated workflow success!

Great job adding the templated workflow. Adding that file to this branch is enough for GitHub Actions to begin running CI on your repository. This takes a couple of minutes, so let's take this opportunity to learn about some of the components of the workflow file you just added. We'll dive deeper into some of the key elements of this file in future steps of the course.

Step 2: Run a templated workflow

I'll respond when GitHub Actions finishes running the workflow. You can follow along in the Actions tab, or by clicking Details on the pending status below.

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Actions workflow not running? Click here

When a GitHub Actions workflow is running, you should see some checks in progress, like the screenshot below.

If the checks don't appear or if the checks are stuck in progress, there's a few things you can do to try and trigger them:

• Refresh the page, it's possible the workflow ran and the page just hasn't been updated with that change
• Try making a commit on this branch. Our workflow is triggered with a push event, and committing to this branch will result in a new push
• Edit the workflow file on GitHub and ensure there are no red lines indicating a syntax problem

[github-learning-lab]

'on:'

The on: field is what tells GitHub Actions when to run. In this case, we're running the workflow anytime there's a push.

To learn more about the fields discussed here, see:

• Workflow syntax for GitHub Actions: on: on GitHub Help
• Events that trigger workflows on GitHub Help

[github-learning-lab]

Jobs

The jobs: block defines the core component of an Actions workflow. Workflows are made of jobs, and our template workflow defines a single job with the identifier build.

Every job also needs a specific host machine on which to run, the runs-on: field is how we specify it. The template workflow is running the build job in the latest version of Ubuntu, a Linux-based operating system.

To learn more about the fields discussed here, see:

• Workflow syntax for GitHub Actions: jobs: on GitHub Help
• Workflow syntax for GitHub Actions: jobs.<job_id>: on GitHub Help
• Workflow syntax for GitHub Actions: jobs.<job_id>.runs-on: on GitHub Help
• Virtual environments for GitHub Actions on GitHub Help
• Ubuntu on Wikipedia

[github-learning-lab]

Vocabulary

Workflows, steps, actions, and jobs

Let's dig into the vocabulary of GitHub Actions.

• Workflow: A workflow is a unit of automation from start to finish, including the definition of what triggers the automation, what environment or other aspects should be taken account during the automation, and what should happen as a result of the trigger.
• Job: A job is a section of the workflow, and is made up of one or more steps. In this section of our workflow, the template defines the steps that make up the build job.
• Step: A step represents one effect of the automation. A step could be defined as a GitHub Action, or another unit, like printing something to the console.
• Action: A GitHub Action is a piece of automation written in a way that is compatible with workflows. Actions can be written by GitHub, by the open source community, or you can write them yourself!

What is checkout?

The power of GitHub Actions lies in access to actions written by the ✨ GitHub community. Here, we'll use two Actions officially written and supported by GitHub:

• actions/checkout@v2 is used to ensure our virtual machine has a copy of our codebase. The checked out code will be used to run tests against.
• actions/setup-node@v1 is used to set up proper versions of Node.js since we'll be performing testing against multiple versions.

To learn more about the fields discussed here, see:

• Workflow syntax for GitHub Actions: jobs.<job_id>.steps: on GitHub Help
• Referencing actions in your workflow on GitHub Help
• Source repository for the actions/checkout action
• Source repository for the actions/setup-node action

[github-learning-lab]

'run:'

In addition to running pre-built actions, the workflow can also execute commands, just as you would if you had direct access to the virtual machine. In this portion of the template workflow, we run some common commands relevant to Node.js projects, like npm install to install dependencies and npm test to run the chosen testing framework.

To learn more about the fields discussed here, see:

• Workflow syntax for GitHub Actions: jobs.<job_id>.steps.run: on GitHub Help
• npm install on the npm Documentation
• npm run on the npm Documentation
• npm test on the npm Documentation

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If you don't see an explanation of your CI logs below when the workflow has executed, refresh this page.

[github-learning-lab]

Running - and failing - workflow

The workflow ran! But it failed 😭. But, that's OK. Every time CI fails, it's an opportunity to learn from what's causing it. By running CI with GitHub Actions, we have access to the logs for the attempted build. These are found:

• In the Actions tab
• In the merge box for this pull request, by clicking on "Details".

If you navigate over to the build logs, you may notice that the error is "No tests found".

Learning how to read build logs and isolate the cause of the problem is an art on its own. We'll try and cover some of the basics here. In our case, the source of the error is the npm test command. The npm test command looks for a testing framework. We want to use Jest, as we mentioned earlier. Jest requires unit tests in a directory named __test__. A __test__ directory doesn't exist on this branch.

Step 3: Add your first test

Not to worry, I've got you covered! Navigate to the open pull request titled Add Jest tests and merge it into this branch. That'll get us the test files we need. I'll respond when you merge the Add Jest tests pull request into this branch.

⌨️ Activity: Add your first test script for CI to pick up

1. Navigate to the open pull request titled Add Jest tests
2. Merge the pull request