Show a helpful message when .all-contributorsrc doesn't exist. (#23)

* Show a helpful message when .all-contributorsrc doesn't exist.

* Adding unit tests.

* Better test descriptions.

* Just code improvements.

cli.js

@@ -2,7 +2,6 @@
 /* eslint-disable no-console */
 'use strict';
 
-var fs = require('fs');
 var path = require('path');
 var yargs = require('yargs');
 var inquirer = require('inquirer');
@@ -31,11 +30,10 @@ var argv = yargs
   .default('config', defaultRCFile)
   .config('config', function (configPath) {
     try {
-      return JSON.parse(fs.readFileSync(configPath, 'utf-8'));
+      return util.configFile.readConfig(configPath);
     } catch (error) {
       if (configPath !== defaultRCFile) {
-        console.error(error.message);
-        process.exit(1);
+        onError(error);
       }
     }
   })
@@ -80,17 +78,12 @@ function addContribution(argv, cb) {
 
 function onError(error) {
   if (error) {
-    return console.error(error);
+    console.error(error.message);
+    process.exit(1);
   }
 }
 
 function promptForCommand(argv, cb) {
-  try {
-    fs.statSync(argv.config);
-  } catch (error) { // No config file --> first time using the command
-    return cb('init');
-  }
-
   var questions = [{
     type: 'list',
     name: 'command',

lib/util/config-file.js

@@ -4,7 +4,14 @@ var fs = require('fs');
 var _ = require('lodash/fp');
 
 function readConfig(configPath) {
-  return JSON.parse(fs.readFileSync(configPath, 'utf-8'));
+  try {
+    return JSON.parse(fs.readFileSync(configPath, 'utf-8'));
+  } catch (error) {
+    if (error.code === 'ENOENT') {
+      throw new Error('Configuration file not found: ' + configPath);
+    }
+    throw error;
+  }
 }
 
 function writeConfig(configPath, content, cb) {
@@ -12,7 +19,12 @@ function writeConfig(configPath, content, cb) {
 }
 
 function writeContributors(configPath, contributors, cb) {
-  var config = readConfig(configPath);
+  var config;
+  try {
+    config = readConfig(configPath);
+  } catch (error) {
+    return cb(error);
+  }
   var content = _.assign(config, {contributors: contributors});
   return writeConfig(configPath, content, cb);
 }

lib/util/config-file.test.js

@@ -0,0 +1,18 @@
+import test from 'ava';
+import configFile from './config-file.js';
+
+const absentFile = './abc';
+const expected = 'Configuration file not found: ' + absentFile;
+
+test('Reading an absent configuration file throws a helpful error', t => {
+  t.throws(() => {
+    configFile.readConfig(absentFile);
+  }, expected);
+});
+
+test.cb('Writing contributors in an absent configuration file throws a helpful error', t => {
+  configFile.writeContributors(absentFile, [], error => {
+    t.is(error.message, expected);
+    t.end();
+  });
+});