refactor: default value is exposed to variable

Author: azu

lib/get-test-dir.js

@@ -1,6 +1,7 @@
 // LICENSE : MIT
 "use strict";
 var normalizeDir = require("./normalize-dir");
+var defaultTestDir = "test/";
 /**
  * Return `dir/` string
  * always suffix with `/`
@@ -13,7 +14,7 @@ function getTestDirFromPkg(pkg) {
         typeof pkg.directories.test === 'string') {
         return normalizeDir(pkg.directories.test);
     }
-    return "test/"; // default value
+    return defaultTestDir;
 }
 
 module.exports = getTestDirFromPkg;