support "yarn create qawolf"

packages/create-qawolf/src/cli.ts

@@ -1,5 +1,5 @@
 import input from '@inquirer/input';
-import { cyan, bold } from 'kleur';
+import { bold, cyan } from 'kleur';
 import { getPackageJsonPath } from './packageJson';
 import { Packages } from './types';
 
@@ -15,12 +15,19 @@ export const logError = (error: Error): void => {
   }
 };
 
-export const logNpmInstall = (packages: Packages): void => {
+export const logInstallDependencies = (
+  packages: Packages,
+  isYarn = false,
+): void => {
   console.log(cyan(`Installing dependencies`));
 
   Object.keys(packages).forEach(name => {
     const version = packages[name];
-    console.log(cyan(`npm install --save-dev ${name}@${version}`));
+    console.log(
+      cyan(
+        `${isYarn ? 'yarn add' : 'npm install --save-dev'} ${name}@${version}`,
+      ),
+    );
   });
 };
 
@@ -34,8 +41,12 @@ export const logUseTypeScript = (useTypeScript: boolean): void => {
   );
 };
 
-export const promptRootDir = (): Promise<string> =>
-  input({
+export const promptRootDir = (): Promise<string> => {
+  // create a line break before our CLI prompt
+  console.log();
+
+  return input({
     message: 'rootDir: Directory to create tests in',
     default: '.qawolf',
   });
+};

packages/create-qawolf/src/config.ts

@@ -17,6 +17,9 @@ export const detectTypeScript = async (): Promise<boolean> => {
   });
 };
 
+export const detectYarn = (): boolean =>
+  (process.env.npm_execpath || '').includes('yarn');
+
 export const writeConfig = async ({
   rootDir,
   useTypeScript,

packages/create-qawolf/src/index.ts

@@ -2,18 +2,19 @@
 import { install as installCi } from 'playwright-ci';
 import {
   logError,
-  logNpmInstall,
+  logInstallDependencies,
   logUseTypeScript,
   promptRootDir,
 } from './cli';
-import { detectTypeScript, writeConfig } from './config';
-import { addDevDependencies, readPackageJson, npmInstall } from './packageJson';
+import { detectTypeScript, detectYarn, writeConfig } from './config';
+import {
+  addDevDependencies,
+  installDependencies,
+  readPackageJson,
+} from './packageJson';
 
 (async (): Promise<void> => {
   try {
-    // create a new line for yarn create
-    console.log();
-
     // run this first to ensure package.json
     await readPackageJson();
 
@@ -27,8 +28,10 @@ import { addDevDependencies, readPackageJson, npmInstall } from './packageJson';
     await writeConfig({ rootDir, useTypeScript });
 
     const packages = await addDevDependencies(useTypeScript);
-    logNpmInstall(packages);
-    npmInstall();
+
+    const isYarn = detectYarn();
+    logInstallDependencies(packages, isYarn);
+    installDependencies(isYarn);
   } catch (error) {
     logError(error);
     process.exit(1);

packages/create-qawolf/src/packageJson.ts

@@ -76,6 +76,6 @@ export const addDevDependencies = async (
   return packages;
 };
 
-export const npmInstall = (): void => {
-  execSync('npm install', { stdio: 'inherit' });
+export const installDependencies = (useYarn = false): void => {
+  execSync(useYarn ? 'yarn' : 'npm install', { stdio: 'inherit' });
 };