gulpfile.js

var del = require("del");
var fs = require('fs');
var gulp = require("gulp");
var istanbul = require("gulp-istanbul");
var mocha = require("gulp-mocha");
var path = require("path");
var shell = require("shelljs");
var tsb = require("gulp-tsb");
var tslint = require("gulp-tslint");

var buildDirectory = "_build";
var srcBuildDirectory = "_build/src";
var codeCoverageDirectory = buildDirectory + "/codeCoverage";
var packageDirectory = buildDirectory + "/package";
var sourcePaths = {
    typescriptFiles: "src/**/*.ts",
    copyFiles: ["src/**/*.png", "src/**/*.json", "src/**/*.md", "src/tasks/**/invoke*.js"],
    tasksPath: "src/tasks"
};
var testPaths = {
    typescriptFiles: "tests/**/*.ts",
    compiledTestFiles: buildDirectory + "/tests/**/*Tests.js"
};
var packageManifestFile = "vss-extension.json";
var nodeModulesDirectory = "node_modules";

var compilation = tsb.create({
    target: 'es5',
    module: 'commonjs',
    declaration: false,
    verbose: false
});

exports.clean = gulp.series(clean);
exports.lint = gulp.series(clean, lint);
exports.compile = gulp.series(clean, lint, compile);
exports.build = gulp.series(clean, lint, compile, build);
exports.test = gulp.series(clean, lint, compile, build, test);
exports.package = gulp.series(clean, lint, compile, build, test, package);
exports.default = gulp.series(clean, lint, compile, build, test);

function clean() {
	return del([buildDirectory]);
}

function lint() {
    return gulp.src([sourcePaths.typescriptFiles, testPaths.typescriptFiles])
        .pipe(tslint({ formatter: "verbose" }))
        .pipe(tslint.report());
}

function compile() {
    return gulp.src([sourcePaths.typescriptFiles, testPaths.typescriptFiles], { base: "." })
        .pipe(compilation())
        .pipe(gulp.dest(buildDirectory))
        .pipe(istanbul({includeUntested: true}))
        .pipe(istanbul.hookRequire());
}

function build() {
    return gulp.src(sourcePaths.copyFiles, { base: "." })
        .pipe(gulp.dest(buildDirectory));
}

function test() {
    return gulp.src(testPaths.compiledTestFiles, {read: false})
        .pipe(mocha());
}

async function package() {
    return getNodeDependencies(function() {
        copyNodeModulesToTasks();
        createVsixPackage();
    });
}

var getNodeDependencies = function(callback) {
    del(packageDirectory);
    shell.mkdir("-p", path.join(packageDirectory, nodeModulesDirectory));
    shell.cp("-f", "package.json", packageDirectory);
    shell.pushd(packageDirectory);
    
    var npmPath = shell.which("npm");
    var npmInstallCommand = '"' + npmPath + '" install --production';
    executeCommand(npmInstallCommand, function() {
        shell.popd();
        callback();
    });
}

var copyNodeModulesToTasks = function() {
    fs.readdirSync(sourcePaths.tasksPath).forEach(function(taskName) {
        var taskpath = path.join(buildDirectory, sourcePaths.tasksPath, taskName);
        del(path.join(taskpath, nodeModulesDirectory));
        shell.cp("-rf", path.join(packageDirectory, nodeModulesDirectory), taskpath);
    });
}

var createVsixPackage = function() {
    var packagingCmd = "tfx extension create --manifeset-globs " + packageManifestFile + " --root " + srcBuildDirectory + " --output-path " + packageDirectory;
    executeCommand(packagingCmd, function() {});
}

var executeCommand = function(cmd, callback) {
    shell.exec(cmd, {silent: true}, function(code, output) {
       if(code != 0) {
           console.error("command failed: " + cmd + "\nManually execute to debug");
       }
       else {
           callback();
       }
    });
}