This code provides a way to mock the Angular CLI (ng) within tests, allowing for controlled execution and simulation of file system interactions and TypeScript compilation. This enables more reliable testing of Angular projects.

Run example

npm run import -- "Run angular-cli commands from nodejs"

Run angular-cli commands from nodejs

var importer = require('../Core');
var mockTypescriptFs = importer.import("memory-fs rewire");
// overlay out temp filesystem on top of current filesystem
var cli = require('@angular/cli');

var TEST_CMD = ['generate', 'component', 'test'];

// use utility/filesystem to mock all fs and typescript commands

// call the CLI just like from command line
function ng(project, args = TEST_CMD) {
    mockTypescriptFs(project);
    // set up project path
    var previous = process.cwd();

    var conf = {
        cliArgs: args,
        inputStream: null,
        outputStream: process.stdout
    };
    process.chdir(project);
    
    // execute
    return cli(conf);
};
module.exports = ng;

const { importFs, importRewire } = require('../Core');
const memoryFs = importFs('memory-fs','rewire');

const angularCli = require('@angular/cli');
const { normalize } = angularCli;

const DEFAULT_CMD = ['generate', 'component', 'test'];

/**
 * Mocks the TypeScript file system and executes the Angular CLI command.
 * 
 * @param {string} project - The name of the project.
 * @param {string[]} [args=DEFAULT_CMD] - The arguments to pass to the CLI.
 * @returns {Promise} The result of the CLI command.
 */
function ng(project, args = DEFAULT_CMD) {
    // Mock the file system
    memoryFs(project);

    // Set up the project path
    const previousCwd = process.cwd();
    process.chdir(project);

    // Get the normalized path
    const projectPath = normalize(project);

    // Set up the CLI configuration
    const config = {
        cliArgs: args,
        inputStream: null,
        outputStream: process.stdout,
        projectPath,
    };

    // Execute the CLI command
    return angularCli(config);
}

module.exports = ng;

This code sets up a way to mock the Angular CLI (ng) commands within a test environment.

Here's a breakdown:

1. Imports: It imports the Core module (likely containing utility functions) and memory-fs rewire for mocking the filesystem and TypeScript compiler.

2. Mocking: It uses mockTypescriptFs to replace the real filesystem with a mock one, allowing tests to control file system interactions.

3. CLI Execution: The ng function takes a project path and an array of CLI arguments (defaults to generate component test).

4. Environment Setup: It changes the current working directory to the project path and sets up a configuration object for the CLI execution.

5. CLI Execution: It executes the Angular CLI using the provided configuration and arguments.

6. Output: The output of the CLI execution is redirected to the standard output (process.stdout).

In essence, this code allows you to run Angular CLI commands in a controlled environment where you can simulate file system interactions and TypeScript compilation, making it easier to write reliable tests for your Angular projects.