tessl/npm-loopback--build

A comprehensive set of build tools and configurations for LoopBack 4 and TypeScript projects providing CLI commands for compilation, linting, testing, and coverage

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Overview

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Code Coverage

Name: tessl/npm-loopback--build
Author: tessl

NYC code coverage wrapper for generating comprehensive test coverage reports with minimal configuration.

Capabilities

lb-nyc Command

Runs NYC (Istanbul) code coverage tool with passthrough support for all NYC options.

/**
 * NYC code coverage function with full option passthrough
 * @param argv - Command line arguments including NYC options and target command
 * @param options - Execution options for dry run and process control
 * @returns ChildProcess when executed, string when dry run
 */
function nyc(argv: string[], options?: RunOptions): ChildProcess | string;

CLI Usage:

# Run tests with coverage
lb-nyc npm run mocha

# Run tests with coverage using lb-mocha
lb-nyc lb-mocha "dist/__tests__"

# Generate coverage report
lb-nyc report

# Generate HTML coverage report
lb-nyc report --reporter=html

# Generate LCOV report for CI
lb-nyc report --reporter=text-lcov

# Run with custom configuration
lb-nyc --include "dist/src/**" npm test

Programmatic Usage:

import { nyc } from "@loopback/build";

// Run tests with coverage
const child = nyc(["npm", "run", "mocha"]);

// Dry run to see command
const command = nyc(["--reporter=html", "npm", "test"], { dryRun: true });
console.log(command); // Shows the NYC command that would be executed

// Run coverage in custom directory
nyc(["lb-mocha", "dist/__tests__"], { cwd: "/path/to/project" });

Configuration Discovery

Automatically discovers NYC configuration files in the project.

Configuration Search Order:

.nycrc in project root
.nycrc.json in project root
.nycrc.yaml in project root
.nycrc.yml in project root
nyc section in package.json
Falls back to @loopback/build/config/.nycrc

Default Configuration:

// @loopback/build/config/.nycrc contents:
interface NYCConfig {
  extension: [".js", ".ts"];    // File extensions to instrument
  reporter: ["html"];           // Coverage report format
  "exclude-after-remap": false; // Include remapped files in coverage
}

Report Generation

Supports all NYC reporters and report generation options.

interface NYCReporters {
  "text": string;         // Console text output
  "text-summary": string; // Brief console summary
  "html": string;         // HTML report in coverage/ directory
  "lcov": string;         // LCOV format for tools
  "json": string;         // JSON format
  "json-summary": string; // JSON summary
  "cobertura": string;    // Cobertura XML format
  "teamcity": string;     // TeamCity format
  "clover": string;       // Clover XML format
}

Usage Examples:

# Multiple reporters
lb-nyc --reporter=text --reporter=html npm test

# Custom output directory
lb-nyc --report-dir=./coverage-reports npm test

# Generate report from existing data
lb-nyc report --reporter=lcov

Integration with Test Runners

Seamlessly integrates with various test runners and npm scripts.

With Mocha:

# Using lb-mocha
lb-nyc lb-mocha "dist/__tests__"

# Using npm script
lb-nyc npm run mocha

# Using standard mocha
lb-nyc ./node_modules/.bin/mocha "dist/__tests__"

With Jest:

# Using Jest
lb-nyc npm run jest

# Direct Jest execution
lb-nyc jest --coverage=false

Coverage Thresholds

Supports coverage threshold enforcement.

interface CoverageThresholds {
  "check-coverage": boolean;      // Enable threshold checking
  "lines": number;               // Line coverage threshold
  "functions": number;           // Function coverage threshold
  "branches": number;            // Branch coverage threshold
  "statements": number;          // Statement coverage threshold
}

Usage:

# Enforce 80% coverage
lb-nyc --check-coverage --lines 80 --functions 80 --branches 80 --statements 80 npm test

# Per-file thresholds
lb-nyc --check-coverage --per-file --lines 80 npm test

File Inclusion and Exclusion

Flexible file pattern support for coverage instrumentation.

interface FilePatterns {
  "include": string[];    // Glob patterns for files to include
  "exclude": string[];    // Glob patterns for files to exclude
  "extension": string[];  // File extensions to instrument
}

Common Patterns:

# Include only source files
lb-nyc --include "src/**" --exclude "**/*.test.js" npm test

# Exclude test files and node_modules
lb-nyc --exclude "**/test/**" --exclude "**/node_modules/**" npm test

# Include TypeScript and JavaScript
lb-nyc --extension .js --extension .ts npm test

Command Line Option Passthrough

All NYC command line options are supported and passed through.

interface NYCOptions {
  "--reporter": string[];           // Coverage reporters to use
  "--report-dir": string;          // Output directory for reports
  "--temp-dir": string;            // Temporary directory for coverage data
  "--include": string[];           // Files to include in coverage
  "--exclude": string[];           // Files to exclude from coverage
  "--extension": string[];         // File extensions to instrument
  "--check-coverage": boolean;     // Enforce coverage thresholds
  "--lines": number;              // Line coverage threshold
  "--functions": number;          // Function coverage threshold
  "--branches": number;           // Branch coverage threshold
  "--statements": number;         // Statement coverage threshold
  "--per-file": boolean;          // Apply thresholds per file
  "--skip-full": boolean;         // Skip files with 100% coverage
  "--show-process-tree": boolean; // Show process tree
  "--instrument": boolean;        // Enable instrumentation
  "--source-map": boolean;        // Enable source map support
  "--produce-source-map": boolean; // Generate source maps
  "--all": boolean;               // Include all files in report
  "--cache": boolean;             // Enable instrumentation caching
  "--cache-dir": string;          // Cache directory location
}

Usage Examples

Basic Coverage:

import { nyc } from "@loopback/build";

// Run tests with coverage
nyc(["npm", "run", "test"], { dryRun: false });

// Generate HTML report
nyc(["report", "--reporter=html"], { dryRun: false });

Package.json Integration:

{
  "scripts": {
    "test": "lb-mocha \"dist/__tests__\"",
    "test:coverage": "lb-nyc npm run test",
    "coverage": "npm run test:coverage && open coverage/index.html",
    "coverage:ci": "lb-nyc --reporter=text-lcov npm run test | coveralls"
  },
  "nyc": {
    "include": ["dist/src/**"],
    "exclude": ["dist/__tests__/"],
    "reporter": ["text", "html"],
    "check-coverage": true,
    "lines": 80,
    "functions": 80,
    "branches": 80,
    "statements": 80
  }
}

Configuration File Examples:

// .nycrc
{
  "include": ["dist/src/**"],
  "exclude": [
    "dist/__tests__/",
    "**/*.d.ts"
  ],
  "extension": [".js", ".ts"],
  "reporter": ["text", "html", "lcov"],
  "check-coverage": true,
  "lines": 85,
  "functions": 85,
  "branches": 80,
  "statements": 85,
  "per-file": true,
  "all": true,
  "cache": true
}

CI/CD Integration

Optimized for continuous integration and deployment workflows.

Coverage Upload:

# Generate LCOV for Coveralls
lb-nyc report --reporter=text-lcov | coveralls

# Generate for Codecov
lb-nyc report --reporter=lcovonly
codecov

# Generate for SonarQube
lb-nyc --reporter=lcov --reporter=text-lcov npm test

Threshold Enforcement:

# Fail build if coverage is below threshold
lb-nyc --check-coverage --lines 80 --functions 80 --branches 80 --statements 80 npm test

Error Handling

Proper error handling and reporting for coverage operations.

// Threshold failures exit with non-zero code
// File pattern errors are reported with helpful messages
// Reporter errors show available reporter options
// Configuration errors provide clear guidance