@loopback/build NPM

@loopback/build

This module contains a set of common scripts and default configurations to build LoopBack 4 or other TypeScript modules, including:

lb-tsc: Use tsc to compile typescript files
lb-eslint: Run eslint
lb-prettier: Run prettier
lb-mocha: Run mocha to execute test cases
lb-nyc: Run nyc

These scripts first try to locate the CLI from target project dependencies and fall back to bundled ones in @loopback/build.

Basic use

To use @loopback/build for your package:

Run the following command to add @loopback/build as a dev dependency.

npm i @loopback/build --save-dev

Configure your project package.json as follows:

"scripts": {
    "build": "lb-tsc",
    "build:watch": "lb-tsc --watch",
    "clean": "lb-clean",
    "lint": "npm run prettier:check && npm run eslint",
    "lint:fix": "npm run prettier:fix && npm run eslint:fix",
    "prettier:cli": "lb-prettier \"**/*.ts\" \"**/*.js\"",
    "prettier:check": "npm run prettier:cli -- -l",
    "prettier:fix": "npm run prettier:cli -- --write",
    "eslint": "lb-eslint --report-unused-disable-directives .",
    "eslint:fix": "npm run eslint -- --fix",
    "pretest": "npm run clean && npm run build",
    "test": "lb-mocha \"dist/__tests__\"",
    "posttest": "npm run lint",
    "start": "npm run build && node .",
    "prepublishOnly": "npm run test"
  },

Please remember to replace your-module-name with the name of your module.

Now you run the scripts, such as:

npm run build - Compile TypeScript files and copy resources (non .ts files) to outDir
npm test - Run all mocha tests
npm run lint - Run eslint and prettier on source files

Override default configurations in your project

lb-tsc
By default, lb-tsc searches your project's root directory for tsconfig.build.json then tsconfig.json. If neither of them exists, a tsconfig.json will be created to extend from @loopback/build/config/tsconfig.common.json.
To customize the configuration:
- Create tsconfig.build.json or tsconfig.json in your project's root directory
```
{
  "$schema": "http://json.schemastore.org/tsconfig",
  "extends": "@loopback/build/config/tsconfig.common.json",
  "compilerOptions": {
    "outDir": "dist",
    "rootDir": "src"
  },
  "include": ["src"]
}
```
- Set options explicitly for the script
```
lb-tsc -p tsconfig.json --target es2017 --outDir dist
```
  For more information, see https://www.typescriptlang.org/docs/handbook/compiler-options.html.
- The following un-official compiler options are available:
  Option Description
  --copy-resources Copy all non-typescript files from src and test to outDir, preserving their relative paths.
- Using ttypescript
  Stability: ⚠️Experimental⚠️
  If you would like to use ttypescript and its available plugins, you can substitute lb-tsc with lb-ttsc, or pass the option lb-tsc --use-ttypescript. If ttypescript is not installed, the default TypeScript compiler tsc will be used instead.

Option	Description
`--copy-resources`	Copy all non-typescript files from `src` and `test` to `outDir`, preserving their relative paths.

Run builds

npm run build

Run code coverage reports

lb-nyc

lb-nyc is a simple wrapper for nyc.

To customize the configuration:

Create .nycrc in your project's root directory

{
  "include": ["dist"],
  "exclude": ["dist/__tests__/"],
  "extension": [".js", ".ts"],
  "reporter": ["text", "html"],
  "exclude-after-remap": false
}

Update your package.json scripts:

"precoverage": "npm test",
"coverage": "open coverage/index.html",
"coverage:ci": "lb-nyc report --reporter=text-lcov | coveralls",
"test": "lb-nyc npm run mocha",
"test:ci": "lb-nyc npm run mocha"

coverage:ci sets up integration with Coveralls.

A note on console logs printed by tests

We consider (console) logging from tests as a bad practice, because such logs usually clutter the test output and make it difficult to distinguish legitimate error messages from the noise.

By default, lb-mocha detects when the tests and/or the application tested have printed console logs and fails the test run with the following message:

=== ATTENTION - INVALID USAGE OF CONSOLE LOGS DETECTED ===

If you need more information about behavior in the test, then the first choice should be to use a better or more descriptive error assertion. If that's not possible, then use debug statements to print additional information when explicitly requested.

A typical situation is that a test is sending an HTTP request and the server responds with an error code as expected. However, because the server is configured to log failed requests, it will print a log also for requests where the failure was expected and intentional. The solution is to configure your REST server to suppress error messages for that specific error code only. Our @loopback/testlab module is providing a helper createUnexpectedHttpErrorLogger that makes this task super easy.

Alternatively, it's also possible to disable detection of console logs by calling lb-mocha with --allow-console-logs argument.