feat(error): Show a more descriptive error when the script was not fo…

…und (#7)

Until now, the error message displayed was kind of short and uninformative. This PR makes the error
message more informative by displaying the name of the script that was not found.

.all-contributorsrc

@@ -48,6 +48,13 @@
         "doc",
         "test"
       ]
+    },
+    {
+      "login": "giladgo",
+      "name": "Gilad Goldberg",
+      "avatar_url": "https://avatars.githubusercontent.com/u/1915716?v=3",
+      "profile": "https://github.com/giladgo",
+      "contributions": []
     }
   ]
 }

README.md

@@ -9,7 +9,7 @@ All the benefits of npm scripts without the cost of a bloated package.json and l
 [![MIT License][license-badge]][LICENSE]
 [![PRs Welcome][prs-badge]](http://makeapullrequest.com)
 [![Donate][donate-badge]][donate]
-[![All Contributors](https://img.shields.io/badge/all_contributors-4-orange.svg?style=flat-square)](#contributors)
+[![All Contributors](https://img.shields.io/badge/all_contributors-5-orange.svg?style=flat-square)](#contributors)
 
 ## The problem
 
@@ -238,8 +238,8 @@ benefits of npm scripts I wanted to keep).
 Thanks goes to these people ([emoji key][emojis]):
 
 <!-- ALL-CONTRIBUTORS-LIST:START - Do not remove or modify this section -->
-| [![Kent C. Dodds](https://avatars.githubusercontent.com/u/1500684?v=3&s=100)<br /><sub>Kent C. Dodds</sub>](http://kent.doddsfamily.us)<br />[💻](https://github.com/kentcdodds/p-s/commits?author=kentcdodds) [📖](https://github.com/kentcdodds/p-s/commits?author=kentcdodds) 🚇 💡 | [![David Wells](https://avatars.githubusercontent.com/u/532272?v=3&s=100)<br /><sub>David Wells</sub>](http://davidwells.io)<br />[💻](https://github.com/kentcdodds/p-s/commits?author=DavidWells) | [![Abhishek Shende](https://avatars.githubusercontent.com/u/802242?v=3&s=100)<br /><sub>Abhishek Shende</sub>](https://twitter.com/abhishekisnot)<br />[💻](https://github.com/kentcdodds/p-s/commits?author=abhishekisnot) [⚠️](https://github.com/kentcdodds/p-s/commits?author=abhishekisnot) | [![Rowan Oulton](https://avatars.githubusercontent.com/u/185649?v=3&s=100)<br /><sub>Rowan Oulton</sub>](http://travelog.io)<br />[💻](https://github.com/kentcdodds/p-s/commits?author=rowanoulton) [📖](https://github.com/kentcdodds/p-s/commits?author=rowanoulton) [⚠️](https://github.com/kentcdodds/p-s/commits?author=rowanoulton) |
-| :---: | :---: | :---: | :---: |
+| [<img src="https://avatars.githubusercontent.com/u/1500684?v=3" width="100px;"/><br /><sub>Kent C. Dodds</sub>](http://kent.doddsfamily.us)<br />[💻](https://github.com/kentcdodds/p-s/commits?author=kentcdodds) [📖](https://github.com/kentcdodds/p-s/commits?author=kentcdodds) 🚇 💡 | [<img src="https://avatars.githubusercontent.com/u/532272?v=3" width="100px;"/><br /><sub>David Wells</sub>](http://davidwells.io)<br />[💻](https://github.com/kentcdodds/p-s/commits?author=DavidWells) | [<img src="https://avatars.githubusercontent.com/u/802242?v=3" width="100px;"/><br /><sub>Abhishek Shende</sub>](https://twitter.com/abhishekisnot)<br />[💻](https://github.com/kentcdodds/p-s/commits?author=abhishekisnot) [⚠️](https://github.com/kentcdodds/p-s/commits?author=abhishekisnot) | [<img src="https://avatars.githubusercontent.com/u/185649?v=3" width="100px;"/><br /><sub>Rowan Oulton</sub>](http://travelog.io)<br />[💻](https://github.com/kentcdodds/p-s/commits?author=rowanoulton) [📖](https://github.com/kentcdodds/p-s/commits?author=rowanoulton) [⚠️](https://github.com/kentcdodds/p-s/commits?author=rowanoulton) | [<img src="https://avatars.githubusercontent.com/u/1915716?v=3" width="100px;"/><br /><sub>Gilad Goldberg</sub>](https://github.com/giladgo)<br /> |
+| :---: | :---: | :---: | :---: | :---: |
 <!-- ALL-CONTRIBUTORS-LIST:END -->
 
 This project follows the [all-contributors][all-contributors] specification.

src/index.js

@@ -37,7 +37,7 @@ function runPackageScript({scriptConfig, options = {}, scriptName, args}) {
   const scripts = getScriptsFromConfig(scriptConfig, scriptName)
   const script = getScriptToRun(scripts, scriptName)
   if (!isString(script)) {
-    return new Error('scripts must resolve to strings')
+    return new Error('Scripts must resolve to strings. Is there a script named \'' + scriptName + '\'?')
   }
   const command = [script, args].join(' ').trim()
   if (!options.silent) {

src/index.test.js

@@ -22,7 +22,8 @@ test.cb('throws when the script is not a string', t => {
   rewireDeps()
   const scriptConfig = {lint: {script: 42}}
   runPackageScript({scriptConfig, scripts: ['lint']}, ({error}) => {
-    if (!error || !(error instanceof Error) || error.message !== 'scripts must resolve to strings') {
+    if (!error || !(error instanceof Error) ||
+      error.message !== 'Scripts must resolve to strings. Is there a script named \'lint\'?') {
       t.end('Error is not the expected error: ' + JSON.stringify(error))
     }
     t.end()