semesters to planner

app/models/subject_plan.rb

@@ -3,4 +3,5 @@ class SubjectPlan < ApplicationRecord
   belongs_to :subject
 
   validates :subject_id, uniqueness: { scope: :user_id }
+  validates :semester, numericality: { only_integer: true, greater_than: 0 }
 end

spec/models/subject_plan_spec.rb

@@ -0,0 +1,18 @@
+require 'rails_helper'
+
+RSpec.describe SubjectPlan, type: :model do
+  describe 'associations' do
+    it { is_expected.to belong_to(:user) }
+    it { is_expected.to belong_to(:subject) }
+  end
+
+  describe 'validations' do
+    subject { create :subject_plan }
+
+    it {
+      is_expected.to validate_uniqueness_of(:subject_id)
+        .scoped_to(:user_id)
+    }
+    it { is_expected.to validate_numericality_of(:semester).only_integer.is_greater_than(0) }
+  end
+end

test/factories/subject_plans.rb

@@ -0,0 +1,7 @@
+FactoryBot.define do
+  factory :subject_plan do
+    user
+    subject
+    semester { 1 }
+  end
+end