Revert "Add more tests (#4970)"

This reverts commit 05bf574.

Author: mracos

lib/devise/models/database_authenticatable.rb

@@ -65,6 +65,7 @@ def password=(new_password)
 
       # Verifies whether a password (ie from sign in) is the user password.
       def valid_password?(password)
+        return false if password.blank?
         Devise::Encryptor.compare(self.class, encrypted_password, password)
       end
 

test/models/database_authenticatable_test.rb

@@ -148,16 +148,6 @@ def setup
     refute user.valid_password?('654321')
   end
 
-  test 'should be invalid if the password is nil' do
-    user = new_user(password: nil)
-    refute user.valid_password?(nil)
-  end
-
-  test 'should be invalid if the password is blank' do
-    user = new_user(password: '')
-    refute user.valid_password?('')
-  end
-
   test 'should respond to current password' do
     assert new_user.respond_to?(:current_password)
   end