diff --git a/lib/plugin-loader.js b/lib/plugin-loader.js
index 17d84203c..5e54110dd 100644
--- a/lib/plugin-loader.js
+++ b/lib/plugin-loader.js
@@ -22,7 +22,7 @@ function load_plugins(config, plugin_configs, params, sanity_check) {
     if (plugin === null && p.match(/^[^\.\/]/)) {
       plugin = try_load('verdaccio-' + p)
       // compatibility for old sinopia plugins
-      if(!plugin) {
+      if (!plugin) {
         plugin = try_load('sinopia-' + p)
       }
     }
@@ -37,18 +37,18 @@ function load_plugins(config, plugin_configs, params, sanity_check) {
     }
 
     if (plugin === null) {
-      throw Error('"' + p + '" plugin not found\ntry "npm install verdaccio-' + p + '"')
+      throw new Error('"' + p + '" plugin not found\ntry "npm install verdaccio-' + p + '"')
     }
 
     if (typeof(plugin) !== 'function')
-      throw Error('"' + p + '" doesn\'t look like a valid plugin')
+      throw new Error('"' + p + '" doesn\'t look like a valid plugin')
 
     plugin = plugin(plugin_configs[p], params)
 
     if (plugin === null || !sanity_check(plugin))
-      throw Error('"' + p + '" doesn\'t look like a valid plugin')
+      throw new Error('"' + p + '" doesn\'t look like a valid plugin')
 
-    return plugin
+    return plugin;
   })
 
   return plugins
diff --git a/test/unit/partials/test-plugin-storage/invalid-package/package.json b/test/unit/partials/test-plugin-storage/invalid-package/package.json
new file mode 100644
index 000000000..0233c3de0
--- /dev/null
+++ b/test/unit/partials/test-plugin-storage/invalid-package/package.json
@@ -0,0 +1,11 @@
+{
+  "name": "invalid-package",
+  "version": "1.0.0",
+  "description": "",
+  "main": "index.js",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "author": "",
+  "license": "ISC"
+}
diff --git a/test/unit/partials/test-plugin-storage/invalid-plugin-sanity/index.js b/test/unit/partials/test-plugin-storage/invalid-plugin-sanity/index.js
new file mode 100644
index 000000000..97336662e
--- /dev/null
+++ b/test/unit/partials/test-plugin-storage/invalid-plugin-sanity/index.js
@@ -0,0 +1,8 @@
+function ValidVerdaccioPlugin() {
+	return {
+		// not valid method
+		authenticate__: function(){}
+	}
+};
+
+module.exports = ValidVerdaccioPlugin;
diff --git a/test/unit/partials/test-plugin-storage/invalid-plugin-sanity/package.json b/test/unit/partials/test-plugin-storage/invalid-plugin-sanity/package.json
new file mode 100644
index 000000000..d3d2e6d53
--- /dev/null
+++ b/test/unit/partials/test-plugin-storage/invalid-plugin-sanity/package.json
@@ -0,0 +1,11 @@
+{
+  "name": "invalid-plugin-sanity",
+  "version": "1.0.0",
+  "description": "",
+  "main": "index.js",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "author": "",
+  "license": "ISC"
+}
diff --git a/test/unit/partials/test-plugin-storage/invalid-plugin/index.js b/test/unit/partials/test-plugin-storage/invalid-plugin/index.js
new file mode 100644
index 000000000..f053ebf79
--- /dev/null
+++ b/test/unit/partials/test-plugin-storage/invalid-plugin/index.js
@@ -0,0 +1 @@
+module.exports = {};
diff --git a/test/unit/partials/test-plugin-storage/invalid-plugin/package.json b/test/unit/partials/test-plugin-storage/invalid-plugin/package.json
new file mode 100644
index 000000000..45b96c189
--- /dev/null
+++ b/test/unit/partials/test-plugin-storage/invalid-plugin/package.json
@@ -0,0 +1,11 @@
+{
+  "name": "invalid-plugin",
+  "version": "1.0.0",
+  "description": "",
+  "main": "index.js",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "author": "",
+  "license": "ISC"
+}
diff --git a/test/unit/partials/test-plugin-storage/verdaccio-plugin/index.js b/test/unit/partials/test-plugin-storage/verdaccio-plugin/index.js
new file mode 100644
index 000000000..540501af0
--- /dev/null
+++ b/test/unit/partials/test-plugin-storage/verdaccio-plugin/index.js
@@ -0,0 +1,7 @@
+function ValidVerdaccioPlugin() {
+	return {
+		authenticate: function(){}
+	}
+};
+
+module.exports = ValidVerdaccioPlugin;
diff --git a/test/unit/partials/test-plugin-storage/verdaccio-plugin/package.json b/test/unit/partials/test-plugin-storage/verdaccio-plugin/package.json
new file mode 100644
index 000000000..56dc78d45
--- /dev/null
+++ b/test/unit/partials/test-plugin-storage/verdaccio-plugin/package.json
@@ -0,0 +1,11 @@
+{
+  "name": "verdaccio-plugin",
+  "version": "1.0.0",
+  "description": "",
+  "main": "index.js",
+  "scripts": {
+    "test": "echo \"Error: no test specified\" && exit 1"
+  },
+  "author": "",
+  "license": "ISC"
+}
diff --git a/test/unit/plugin_loader.js b/test/unit/plugin_loader.js
new file mode 100644
index 000000000..4bca68f59
--- /dev/null
+++ b/test/unit/plugin_loader.js
@@ -0,0 +1,71 @@
+'use strict';
+
+const assert = require('assert');
+const load_plugins = require('../../lib/plugin-loader').load_plugins;
+const path = require('path');
+
+describe('plugin loader', function() {
+
+	it('testing auth valid plugin loader', function() {
+		let _config = {
+			self_path: path.join(__dirname, './'),
+			max_users: 0,
+			auth: {
+				'./unit/partials/test-plugin-storage/verdaccio-plugin': {}
+			}
+		}
+		let p = load_plugins(_config, _config.auth, {}, function (p) {
+			return p.authenticate || p.allow_access || p.allow_publish;
+		});
+		assert(p.length === 1);
+	});
+
+	it('testing auth plugin invalid plugin', function() {
+		let _config = {
+			self_path: path.join(__dirname, './'),
+			auth: {
+				'./unit/partials/test-plugin-storage/invalid-plugin': {}
+			}
+		}
+		try {
+			load_plugins(_config, _config.auth, {}, function (p) {
+				return p.authenticate || p.allow_access || p.allow_publish;
+			});
+		} catch(e) {
+			assert(e.message === '"./unit/partials/test-plugin-storage/invalid-plugin" doesn\'t look like a valid plugin');
+		}
+	});
+
+	it('testing auth plugin invalid plugin sanityCheck', function() {
+		let _config = {
+			self_path: path.join(__dirname, './'),
+			auth: {
+				'./unit/partials/test-plugin-storage/invalid-plugin-sanity': {}
+			}
+		}
+		try {
+			load_plugins(_config, _config.auth, {}, function (p) {
+				return p.authenticate || p.allow_access || p.allow_publish;
+			});
+		} catch(e) {
+			assert(e.message === '"./unit/partials/test-plugin-storage/invalid-plugin-sanity" doesn\'t look like a valid plugin');
+		}
+	});
+
+	it('testing auth plugin no plugins', function() {
+		let _config = {
+			self_path: path.join(__dirname, './'),
+			auth: {
+				'./unit/partials/test-plugin-storage/invalid-package': {}
+			}
+		}
+		try {
+			load_plugins(_config, _config.auth, {}, function (p) {
+				return p.authenticate || p.allow_access || p.allow_publish;
+			});
+		} catch(e) {
+			assert(e.message === `"./unit/partials/test-plugin-storage/invalid-package" plugin not found\ntry "npm install verdaccio-./unit/partials/test-plugin-storage/invalid-package"`);
+		}
+	});
+
+});