add more tests to models

app/models/block.rb

@@ -3,9 +3,8 @@
 class Block < ApplicationRecord
   include Paginable
 
-  belongs_to :account
-  belongs_to :target_account, class_name: 'Account'
+  belongs_to :account, required: true
+  belongs_to :target_account, class_name: 'Account', required: true
 
-  validates :account, :target_account, presence: true
   validates :account_id, uniqueness: { scope: :target_account_id }
 end

app/models/follow.rb

@@ -3,11 +3,14 @@
 class Follow < ApplicationRecord
   include Paginable
 
-  belongs_to :account, counter_cache: :following_count
-  belongs_to :target_account, class_name: 'Account', counter_cache: :followers_count
+  belongs_to :account, counter_cache: :following_count, required: true
+  
+  belongs_to :target_account,
+             class_name: 'Account',
+             counter_cache: :followers_count,
+             required: true
 
   has_one :notification, as: :activity, dependent: :destroy
 
-  validates :account, :target_account, presence: true
   validates :account_id, uniqueness: { scope: :target_account_id }
 end

app/models/follow_request.rb

@@ -3,12 +3,11 @@
 class FollowRequest < ApplicationRecord
   include Paginable
 
-  belongs_to :account
-  belongs_to :target_account, class_name: 'Account'
+  belongs_to :account, required: true
+  belongs_to :target_account, class_name: 'Account', required: true
 
   has_one :notification, as: :activity, dependent: :destroy
 
-  validates :account, :target_account, presence: true
   validates :account_id, uniqueness: { scope: :target_account_id }
 
   def authorize!

app/models/mention.rb

@@ -1,11 +1,10 @@
 # frozen_string_literal: true
 
 class Mention < ApplicationRecord
-  belongs_to :account, inverse_of: :mentions
-  belongs_to :status
+  belongs_to :account, inverse_of: :mentions, required: true
+  belongs_to :status, required: true
 
   has_one :notification, as: :activity, dependent: :destroy
 
-  validates :account, :status, presence: true
   validates :account, uniqueness: { scope: :status }
 end