Refactor repeated pattern into extracted method

Seems like we'll be checking login status before finding a resource
a lot, so here's a standard way to do it.

lib/travis/api/v3/access_control/generic.rb

@@ -30,6 +30,10 @@ module Travis::API::V3
       false
     end
 
+    def full_access_or_logged_in?
+      full_access? || logged_in?
+    end
+
     def visible_repositories(list)
       # naïve implementation, replaced with smart implementation in specific subclasses
       return list if full_access?

lib/travis/api/v3/service.rb

@@ -66,6 +66,11 @@ module Travis::API::V3
       object
     end
 
+    def check_login_and_find(*args)
+      raise LoginRequired unless access_control.full_access_or_logged_in?
+      find(*args)
+    end
+
     def not_found(actually_not_found = false, type = nil)
       type, actually_not_found = actually_not_found, false if actually_not_found.is_a? Symbol
       error = actually_not_found ? EntityMissing : NotFound

lib/travis/api/v3/services/env_var/delete.rb

@@ -4,8 +4,7 @@ module Travis::API::V3
     params :id, prefix: :env_var
 
     def run!
-      raise LoginRequired unless access_control.logged_in? or access_control.full_access?
-      raise NotFound      unless repository = find(:repository)
+      repository = check_login_and_find(:repository)
       query.delete(repository)
     end
   end

lib/travis/api/v3/services/env_var/find.rb

@@ -4,8 +4,7 @@ module Travis::API::V3
     params :id, prefix: :env_var
 
     def run!
-      raise LoginRequired unless access_control.logged_in? or access_control.full_access?
-      raise NotFound      unless repository = find(:repository)
+      repository = check_login_and_find(:repository)
       query.find(repository)
     end
   end

lib/travis/api/v3/services/env_var/update.rb

@@ -4,8 +4,7 @@ module Travis::API::V3
     params :id, :name, :value, :public, prefix: :env_var
 
     def run!
-      raise LoginRequired unless access_control.logged_in? or access_control.full_access?
-      raise NotFound      unless repository = find(:repository)
+      repository = check_login_and_find(:repository)
       query.update(repository)
     end
   end

lib/travis/api/v3/services/env_vars/create.rb

@@ -4,8 +4,7 @@ module Travis::API::V3
     params :id, :name, :value, :public, prefix: :env_var
 
     def run!
-      raise LoginRequired unless access_control.logged_in? or access_control.full_access?
-      raise NotFound      unless repository = find(:repository)
+      repository = check_login_and_find(:repository)
       env_var = query(:env_vars).create(repository)
       result(:env_var, env_var, status: 201)
     end

lib/travis/api/v3/services/env_vars/for_repository.rb

@@ -1,8 +1,7 @@
 module Travis::API::V3
   class Services::EnvVars::ForRepository < Service
     def run!
-      raise LoginRequired unless access_control.logged_in? or access_control.full_access?
-      raise NotFound      unless repository = find(:repository)
+      repository = check_login_and_find(:repository)
       find(:env_vars, repository)
     end
   end