API for app usage tracking

spec/models/app_usage_spec.rb

@@ -0,0 +1,9 @@
+require 'rails_helper'
+
+RSpec.describe AppUsage, type: :model do
+  let!(:app_usage) { create(:app_usage) }
+
+  it { should validate_presence_of :package_name } 
+  it { should validate_presence_of :usage_duration_in_seconds } 
+  it { should validate_presence_of :used_on } 
+end