Learn About Sample App Tooling

In this step, we walk through the different tools and configurations that are shared across most of the sample apps. We do this by looking at the tooling in the LWC Recipes sample app. 

  1. Using your browser, navigate to trailhead.salesforce.com/sample-gallery.
  2. On the LWC Recipes app tile, click the View on GitHub button to navigate to the lwc-recipes GitHub repo.

Salesforce Project Configurations

First, get to know the Salesforce project setup in the sfdx-project.json config file.

sfdx-project.json file in GitHub

  1. Click the link to view the contents of the sfdx-project.json.
  "packageDirectories": [
      "path": "force-app",
      "default": true,
      "package": "LWCRecipes",
      "versionName": "Summer '20",
      "versionNumber": "3.0.0.NEXT"
  "namespace": "",
  "sourceApiVersion": "49.0",
  "sfdcLoginUrl": "https://login.salesforce.com",
  "packageAliases": {
    "LWCRecipes": "0Ho3t000000KywNCAS",
    "LWCRecipes@3.0.0-2": "04t3t000002kBPFAA2",
    "LWCRecipes@3.0.0-5": "04t3t000002kpZeAAI",
    "LWCRecipes@3.0.0-10": "04t3t000002kpdMAAQ",
    "LWCRecipes@3.0.0-18": "04t3t000002kq69AAA"
  1. Note the packageDirectories config where you can see that we’ve set up unlocked packages for this app. This contains configs for the package name, the file path of the metadata for the package, and version information.
  2. Note also the sourceApiVersion config. As a rule, we update the sample apps with the API version for the current major release, across the config file and all metadata. For this reason, you may see a different value for sourceApiVersion.
  3. Click the Back button in your browser.

Next, we take a look at how we've set up code quality tools. 

Code Quality Tool Setup

In addition to the tooling included in the Salesforce command line, there are some tools we use that run using npm. So even though we don’t use Node.js in any runtime Salesforce code, we still have a package.json to import and configure the developer tools with npm.  



npm is the default package manager for Node.js. It consists of a package registry, a command line interface (CLI), and the npmjs.com website. It is widely adopted for building apps to implement developer tools and even general-purpose command line tools. 

In our sample apps we’re using the npm command line with several developer tools that perform code linting, code formatting, unit testing, and application lifecycle management (ALM) automation. The easiest way to install npm is to install Node.js, which bundles npm. To learn more about npm, visit npmjs.com

  1. Click the link to view the contents of package.json.
  2. Note that since we are only using developer tooling, dependencies is absent.
  3. Look at the devDependencies config, and you can see the packages that we are using as part of our tooling.
  4. The high-level packages we use are:
    • prettier: for formatting code
    • eslint: for code linting
    • sfdx-lwc-jest: the Jest extension for testing Lightning web components
    • husky: to execute actions that verify code before committing to version control
  5. We’ve also encapsulated certain common commands here in the scripts config. In each case, the command is executed using npm run. For instance notice the test:unit script key. You can execute your Lightning web component unit tests by running npm run test:unit from the command line. Here’s how it looks:

Running unit tests with npm run test:unit.

  1. Finish your tour of package.json by clicking your browser’s Back button.

You can see how each of these scripts lets you execute different tools that are installed in the project. 

Unit Testing Configuration

Let's look at how some of them are configured. We use the Jest testing library to execute Lightning web component unit tests. In our case, Salesforce has created an extension that is tailor made for LWC called sfdx-lwc-jest. 

  1. Click the link to view the contents of jest.config.js.
  2. You can extend the default mocks that ship with sfdx-lwc-jest using the moduleNameMapper JavaScript object. Those mock extensions are defined here.
moduleNameMapper: {
    '^@salesforce/apex$': '<rootDir>/force-app/test/jest-mocks/apex',
    '^lightning/navigation$': '<rootDir>/force-app/test/jest-mocks/lightning/navigation',
    '^lightning/platformShowToastEvent$': '<rootDir>/force-app/test/jest-mocks/lightning/platformShowToastEvent',
    '^lightning/uiRecordApi$': '<rootDir>/force-app/test/jest-mocks/lightning/uiRecordApi'
  1. Take note that the ^lightning/navigation$ key defines the location of its mock as <rootDir>/force-app/test/jest-mocks/lightning/navigation. Let’s go find this mock JS code in the GitHub repo.
  2. Click your browser’s Back button.
  3. Click the links force-app, test/jest-mocks, and lightning to find all the Lightning Web Components services mocks.
  4. Click the link to open the navigation.js file contents.
  5. Here you can see how some of the exported functions provided by Lightning NavigationMixin have been mocked for use in Jest tests.
  6. Click your browser’s Back button four times to return to the project root directory.

Automated Code Formatting Configuration

We looked at how to configure the sfdx-lwc-jest tool, now let’s take a look at the Prettier code formatting tool configs. While sfdx-lwc-jest is only for testing LWCs, Prettier performs code formatting on a lot of different files. We’ve even added plug-ins for XML and Apex. LWC-specific formatting rules come bundled with Prettier.

If you look back in the package.json, you can see in scripts that we’ve configured the Prettier script to run against many different file types in this line here: 

"prettier": "prettier --write \"**/*.{cls,cmp,component,css,html,js,json,md,page,trigger,xml,yaml,yml}\""

Let’s see how we configure the Prettier tool. More information on these configurations is in the Prettier documentation

  1. Click the link to open the .prettierrc file.
  2. Note configs for how to set up Prettier to format code, such as enforcing trailing commas, allowing single quotes and tab width.
  3. Also, you can use the overrides key to create custom parse rules. For instance, we use the lwc parser to handle HTML attributes surrounded by curly braces.
"trailingComma": "none",
"singleQuote": true,
"tabWidth": 4,
"overrides": [
        "files": "**/lwc/**/*.html",
        "options": { "parser": "lwc" }
        "files": "*.{cmp,page,component}",
        "options": { "parser": "html" }
  1. Click the browser’s Back button to go back to the root directory.

Just Ignore This

Many tools let you create exceptions to which files they are executed on. Things such as Git, Prettier, ESLint, and the Salesforce CLI all need to know which files they can ignore. Let’s look at one of the configuration files. 

When developing a Salesforce project, some orgs (scratch orgs) are source tracked, meaning an API tracks changes made locally and in the org. Then org-to-local-project syncing can be done automatically using sfdx force:source:push or sfdx force:source:pull. Any parts of your project you want to prevent from automatically syncing are configured in a file called .forceignore

  1. Note the following files .eslintignore, .forceignore, .gitignore, .prettierignore. These define ignore rules for different tools.
  2. Click .forceignore to view its contents.
  3. The items defined in .forceignore will not be tracked or synced by the SourceSync API.
  4. Note that among other items in our project config, we do not sync any settings metadata.
  5. Click the browser’s Back button to go back to the root directory.

GitHub Actions

Good tooling also lets you invoke it automatically in CI/CD processes. This is no different. In our sample apps, we’re using GitHub actions to automate the use of these tools as code is merged and moves between branches. Let’s go find where these files are and see how they use the tooling we’ve looked at. We’ll also look at the execution history of these actions in our repository. 

GitHub actions are a built-in feature in GitHub to define your entire CI/CD process within GitHub. However, Salesforce developer tooling is agnostic to CI/CD tools. Make sure to read the documentation, which has references to other example projects repositories if you have a different preferred CI/CD tool. 

  1. Click the directory links for .github and workflows to go to view the YAML files where the github CI workflows live.
  2. Click the link for scratch-org-sfdx-ci-master.yml to view the file contents.
  3. Look through the file and find the line that says: run: npm run prettier:verify
  4. This is the point in the CI process where Prettier checks to see that the code conforms to the formatting rules specified in its setup.
  5. Across the top of the GitHub UI, select the Actions tab.

GitHub Actions tab.

  1. The list of all GitHub actions workflows is on the left. Click Salesforce DX (scratch org) to see all the times that workflow was executed.

Now you’ve had a tour of the tooling setup in the lwc-recipes GitHub repository. You are ready to dive into using the tools in any of the sample apps. We keep the tooling configuration as uniform as possible. In some cases, however, some apps use a different configuration. Learn more about those apps by completing the other projects in this trail.

We won’t check any of your work in this step. Click Verify step to earn 25 points to complete the project.

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