Support cjs testem configs

Author: NullVoxPopuli

lib/utils/config-reader.js

@@ -5,7 +5,7 @@ const yaml = require('js-yaml');
 const path = require('path');
 const debug = require('debug')('exam:config-reader');
 
-const potentialConfigFiles = ['testem.js', 'testem.json'];
+const potentialConfigFiles = ['testem.js', 'testem.json', 'testem.cjs'];
 
 /**
  * Given an array of file paths, returns the first one that exists and is
@@ -40,11 +40,14 @@ function _readFileByType(file) {
     const fileType = file.split('.').pop();
     switch (fileType) {
       case 'js':
+      case 'cjs':
         return require(file);
       case 'json':
         return fs.readJsonSync(file);
       case 'yaml':
         return yaml.load(fs.readFileSync(file));
+      default:
+        throw new Error(`Unrecognized file extension for: ${file}`);
     }
   }
 }