fix: automatically install with npm if Yarn isn’t available

Closes #5

Author: mischah

generators/app/index.js

@@ -3,6 +3,7 @@ const Generator = require('yeoman-generator');
 const chalk = require('chalk');
 const yosay = require('yosay');
 const superb = require('superb');
+const commandExists = require('command-exists').sync;
 const helper = require('./promptingHelpers');
 
 module.exports = class extends Generator {
@@ -127,22 +128,18 @@ module.exports = class extends Generator {
   }
 
   install() {
+    const hasYarn = commandExists('yarn');
     this.installDependencies({
-      npm: false,
+      npm: !hasYarn,
       bower: false,
-      yarn: true,
-      callback: error => {
-        if (error) {
-          this.log('… or alternatively run ' +
-            chalk.yellow('npm install') +
-            ' instead.');
-        } else {
-          this.log(yosay(`
-            That’s it. Feel free to fire up the server with ${chalk.green('npm run start:dev')}
-              or use our subgenerator to create endpoints.
-          `));
-        }
-      }
+      yarn: hasYarn
     });
   }
+
+  end() {
+    this.log(yosay(`
+      That’s it. Feel free to fire up the server with ${chalk.green('npm run start:dev')}
+        or use our subgenerator to create endpoints: ${chalk.yellow('yo http-fake-backend:endpoint')}
+    `, {maxLength: 40}));
+  }
 };

package-lock.json

@@ -32,6 +32,7 @@
   ],
   "dependencies": {
     "chalk": "2.0.1",
+    "command-exists": "^1.2.2",
     "superb": "1.3.0",
     "title-case": "^2.1.1",
     "yeoman-generator": "^1.1.1",

package.json

@@ -411,6 +411,10 @@ combined-stream@^1.0.5, combined-stream@~1.0.5:
   dependencies:
     delayed-stream "~1.0.0"
 
+command-exists@^1.2.2:
+  version "1.2.2"
+  resolved "https://registry.yarnpkg.com/command-exists/-/command-exists-1.2.2.tgz#12819c64faf95446ec0ae07fe6cafb6eb3708b22"
+
 commander@2.9.0:
   version "2.9.0"
   resolved "https://registry.yarnpkg.com/commander/-/commander-2.9.0.tgz#9c99094176e12240cb22d6c5146098400fe0f7d4"
@@ -457,7 +461,7 @@ create-error-class@^3.0.0:
   dependencies:
     capture-stack-trace "^1.0.0"
 
-cross-spawn@^5.0.1:
+cross-spawn@^5.0.1, cross-spawn@^5.1.0:
   version "5.1.0"
   resolved "https://registry.yarnpkg.com/cross-spawn/-/cross-spawn-5.1.0.tgz#e8bd0efee58fcff6f8f94510a0a554bbfa235449"
   dependencies:
@@ -649,7 +653,7 @@ eslint-scope@^3.7.1:
     esrecurse "^4.1.0"
     estraverse "^4.1.1"
 
-eslint@^4.0.0, eslint@^4.2.0:
+eslint@^4.0.0:
   version "4.2.0"
   resolved "https://registry.yarnpkg.com/eslint/-/eslint-4.2.0.tgz#a2b3184111b198e02e9c7f3cca625a5e01c56b3d"
   dependencies:
@@ -687,6 +691,47 @@ eslint@^4.0.0, eslint@^4.2.0:
     table "^4.0.1"
     text-table "~0.2.0"
 
+eslint@^4.3.0:
+  version "4.3.0"
+  resolved "https://registry.yarnpkg.com/eslint/-/eslint-4.3.0.tgz#fcd7c96376bbf34c85ee67ed0012a299642b108f"
+  dependencies:
+    ajv "^5.2.0"
+    babel-code-frame "^6.22.0"
+    chalk "^1.1.3"
+    concat-stream "^1.6.0"
+    cross-spawn "^5.1.0"
+    debug "^2.6.8"
+    doctrine "^2.0.0"
+    eslint-scope "^3.7.1"
+    espree "^3.4.3"
+    esquery "^1.0.0"
+    estraverse "^4.2.0"
+    esutils "^2.0.2"
+    file-entry-cache "^2.0.0"
+    functional-red-black-tree "^1.0.1"
+    glob "^7.1.2"
+    globals "^9.17.0"
+    ignore "^3.3.3"
+    imurmurhash "^0.1.4"
+    inquirer "^3.0.6"
+    is-resolvable "^1.0.0"
+    js-yaml "^3.8.4"
+    json-stable-stringify "^1.0.1"
+    levn "^0.3.0"
+    lodash "^4.17.4"
+    minimatch "^3.0.2"
+    mkdirp "^0.5.1"
+    natural-compare "^1.4.0"
+    optionator "^0.8.2"
+    path-is-inside "^1.0.2"
+    pluralize "^4.0.0"
+    progress "^2.0.0"
+    require-uncached "^1.0.3"
+    semver "^5.3.0"
+    strip-json-comments "~2.0.1"
+    table "^4.0.1"
+    text-table "~0.2.0"
+
 espree@^3.4.3:
   version "3.4.3"
   resolved "https://registry.yarnpkg.com/espree/-/espree-3.4.3.tgz#2910b5ccd49ce893c2ffffaab4fd8b3a31b82374"
@@ -935,6 +980,10 @@ fs.realpath@^1.0.0:
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/fs.realpath/-/fs.realpath-1.0.0.tgz#1504ad2523158caa40db4a2787cb01411994ea4f"
 
+functional-red-black-tree@^1.0.1:
+  version "1.0.1"
+  resolved "https://registry.yarnpkg.com/functional-red-black-tree/-/functional-red-black-tree-1.0.1.tgz#1b0ab3bd553b2a0d6399d29c0e3ea0b252078327"
+
 gaze@^0.5.1:
   version "0.5.2"
   resolved "https://registry.yarnpkg.com/gaze/-/gaze-0.5.2.tgz#40b709537d24d1d45767db5a908689dfe69ac44f"
@@ -2774,6 +2823,10 @@ semver@^4.1.0:
   version "4.3.6"
   resolved "https://registry.yarnpkg.com/semver/-/semver-4.3.6.tgz#300bc6e0e86374f7ba61068b5b1ecd57fc6532da"
 
+semver@^5.3.0:
+  version "5.4.1"
+  resolved "https://registry.yarnpkg.com/semver/-/semver-5.4.1.tgz#e059c09d8571f0540823733433505d3a2f00b18e"
+
 semver@~5.0.1:
   version "5.0.3"
   resolved "https://registry.yarnpkg.com/semver/-/semver-5.0.3.tgz#77466de589cd5d3c95f138aa78bc569a3cb5d27a"
@@ -3454,9 +3507,9 @@ yeoman-test@1.7.0:
     yeoman-environment "^2.0.0"
     yeoman-generator "^1.1.0"
 
-yosay@^2.0.0:
-  version "2.0.0"
-  resolved "https://registry.yarnpkg.com/yosay/-/yosay-2.0.0.tgz#0f3d2bb01f7f25362c127212f53c1572906333fe"
+yosay@^2.0.1:
+  version "2.0.1"
+  resolved "https://registry.yarnpkg.com/yosay/-/yosay-2.0.1.tgz#078167f0365732e5c82d3f64633f9cd3a0526d2f"
   dependencies:
     ansi-regex "^2.0.0"
     ansi-styles "^3.0.0"