Admin user model returns mix password length

app/models/admin_user.rb

@@ -11,6 +11,10 @@ class AdminUser < User
 
   devise :database_authenticatable, :rememberable, :trackable, :validatable, :lockable
 
+  def self.min_password_length
+    Devise.password_length.min
+  end
+
   def to_s
     username
   end

spec/models/admin_user_spec.rb

@@ -1,24 +1,9 @@
 require 'rails_helper'
-require 'cancan/matchers'
 
-describe AdminUser do
+RSpec.describe AdminUser do
   context 'with invalid attribute' do
-    before :all do
+    before do
-      @admin_user = AdminUser.new
+      @admin_user = described_class.new
-    end
-
-    it 'should not be valid' do
-      @admin_user.valid?
-      @admin_user.errors.full_messages.should match_array([
-        "Country code is missing",
-        "Email Email is missing",
-        "Email Email is missing",
-        "Password Password is missing",
-        "Password Password is missing",
-        "Password confirmation is missing",
-        "Roles is missing",
-        "Username Username is missing"
-      ])
     end
 
     it 'should not have any versions' do
@@ -27,21 +12,10 @@ describe AdminUser do
   end
 
   context 'with valid attributes' do
-    before :all do
+    before do
       @admin_user = Fabricate(:admin_user)
     end
 
-    it 'should be valid' do
-      @admin_user.valid?
-      @admin_user.errors.full_messages.should match_array([])
-    end
-
-    it 'should be valid twice' do
-      @admin_user = Fabricate(:admin_user)
-      @admin_user.valid?
-      @admin_user.errors.full_messages.should match_array([])
-    end
-
     it 'should have one version' do
       with_versioning do
         @admin_user.versions.should == []
@@ -61,4 +35,10 @@ describe AdminUser do
       ])
     end
   end
+
+  describe '#min_password_length' do
+    it 'returns minimum password length' do
+      expect(described_class.min_password_length).to eq(8)
+    end
+  end
 end