Allow only letters and underscores in Setting code

app/models/setting_entry.rb

@@ -4,6 +4,7 @@ class SettingEntry < ApplicationRecord
   validates :format, presence: true
   validates :group, presence: true
   validate :valid_value_format
+  validates_format_of :code, with: /([a-z])[a-z|_]+[a-z]/
 
   VALUE_FORMATS = {
     string: :string_format,

db/migrate/20200811074839_create_setting_entries.rb

@@ -2,7 +2,7 @@ class CreateSettingEntries < ActiveRecord::Migration[6.0]
   def change
     create_table :setting_entries do |t|
       t.string :code, null: false, index: { unique: true }
-      t.string :value, null: false, default: ''
+      t.string :value
       t.string :group, null: false
       t.string :format, null: false
 

db/structure.sql

@@ -2307,7 +2307,7 @@ CREATE TABLE public.schema_migrations (
 CREATE TABLE public.setting_entries (
     id bigint NOT NULL,
     code character varying NOT NULL,
-    value character varying DEFAULT ''::character varying,
+    value character varying,
     "group" character varying NOT NULL,
     format character varying NOT NULL,
     creator_str character varying,

test/models/setting_entry_test.rb

@@ -2,9 +2,107 @@ require 'test_helper'
 
 class SettingEntryTest < ActiveSupport::TestCase
   def setup
+    @new_setting = SettingEntry.new(code: 'new_setting', value: 'looks great', format: 'string', group: 'other')
   end
 
   def test_fixture_is_valid
     assert setting_entries(:legal_document_is_mandatory).valid?
   end
+
+  def test_can_be_retrieved_via_class_method
+    setting = setting_entries(:legal_document_is_mandatory)
+    assert setting.retrieve, Setting.legal_document_is_mandatory
+  end
+
+  def test_can_be_updated_via_class_method
+    setting = setting_entries(:legal_document_is_mandatory)
+    setting.update(value: 'false')
+    setting.reload
+
+    Setting.legal_document_is_mandatory = true
+    setting.reload
+    assert true, setting.retrieve
+  end
+
+  def test_setting_code_is_required
+    assert @new_setting.valid?
+    @new_setting.code = nil
+    assert_not @new_setting.valid?
+  end
+
+  def test_setting_code_can_only_include_underscore_and_characters
+    assert @new_setting.valid?
+    @new_setting.code = 'a b'
+    assert_not @new_setting.valid?
+
+    @new_setting.code = 'a_b'
+    assert @new_setting.valid?
+  end
+
+  def test_setting_value_can_be_nil
+    assert @new_setting.valid?
+    @new_setting.value = nil
+    assert @new_setting.valid?
+  end
+
+  def test_setting_format_is_required
+    assert @new_setting.valid?
+    @new_setting.format = nil
+    assert_not @new_setting.valid?
+
+    @new_setting.format = 'nonexistant'
+    assert_not @new_setting.valid?
+  end
+
+  def test_setting_group_is_required
+    assert @new_setting.valid?
+    @new_setting.group = nil
+    assert_not @new_setting.valid?
+
+    @new_setting.group = 'random'
+    assert @new_setting.valid?
+  end
+
+  def test_returns_nil_for_unknown_setting
+    assert_nil Setting.unknown_and_definitely_not_saved_setting
+  end
+
+  def test_throws_error_if_updating_unknown_setting
+    assert_raises ActiveRecord::RecordNotFound do
+      Setting.unknown_and_definitely_not_saved_setting = 'hope it fails'
+    end
+  end
+
+  def test_parses_string_format
+    Setting.create(code: 'string_format', value: '1', format: 'string', group: 'random')
+    assert Setting.string_format.is_a? String
+  end
+
+  def test_parses_integer_format
+    Setting.create(code: 'integer_format', value: '1', format: 'integer', group: 'random')
+    assert Setting.integer_format.is_a? Integer
+  end
+
+  def test_parses_float_format
+    Setting.create(code: 'float_format', value: '0.5', format: 'float', group: 'random')
+    assert Setting.float_format.is_a? Float
+  end
+
+  def test_parses_boolean_format
+    Setting.create(code: 'boolean_format', value: 'true', format: 'boolean', group: 'random')
+    assert_equal true, Setting.boolean_format
+
+    Setting.boolean_format = 'false'
+    assert_equal false, Setting.boolean_format
+  end
+
+  def test_parses_hash_format
+    Setting.create(code: 'hash_format', value: '{"hello": "there"}', format: 'hash', group: 'random')
+    assert Setting.hash_format.is_a? Hash
+  end
+
+  def test_parses_array_format
+    Setting.create(code: 'array_format', value: '[1, 2, 3]', format: 'array', group: 'random')
+    assert Setting.array_format.is_a? Array
+  end
 end