Started writing tests that don't hit the db

Author: cronin101

Gemfile

@@ -12,5 +12,9 @@ gem 'colored'
 gem 'pry'
 gem 'pry-coolline'
 gem 'rake'
-gem 'minitest', group: :test
-gem 'codeclimate-test-reporter', group: :test, require: nil
+
+group :test do
+  gem 'activerecord-nulldb-adapter', :git => 'git://github.com/nulldb/nulldb.git'
+  gem 'minitest'
+  gem 'codeclimate-test-reporter', require: nil
+end

db/schema.rb

@@ -0,0 +1,33 @@
+# This file is auto-generated from the current state of the database. Instead
+# of editing this file, please use the migrations feature of Active Record to
+# incrementally modify your database, and then regenerate this schema definition.
+#
+# Note that this schema.rb definition is the authoritative source for your
+# database schema. If you need to create the application database on another
+# system, you should be using db:schema:load, not running all the migrations
+# from scratch. The latter is a flawed and unsustainable approach (the more migrations
+# you'll amass, the slower it'll run and the greater likelihood for issues).
+#
+# It's strongly recommended that you check this file into your version control system.
+
+ActiveRecord::Schema.define(version: 0) do
+
+  # These are extensions that must be enabled in order to support this database
+  enable_extension "plpgsql"
+
+  create_table "ingredients", force: true do |t|
+    t.text    "name",                          null: false
+    t.integer "recipe_frequency", default: 0,  null: false
+    t.integer "recipe_ids",       default: [], null: false, array: true
+  end
+
+  create_table "recipes", force: true do |t|
+    t.text    "source_uri",                         null: false
+    t.text    "source_ingredients", default: [],    null: false, array: true
+    t.integer "ingredient_ids",     default: [],    null: false, array: true
+    t.boolean "has_been_scraped",   default: false, null: false
+    t.text    "title"
+    t.text    "description"
+  end
+
+end

dump_schema.rb

@@ -0,0 +1,3 @@
+require './environment.rb'
+
+ActiveRecord::SchemaDumper.dump ActiveRecord::Base.connection, File.open("#{__dir__}/db/schema.rb", 'w')

models/ingredient.rb

@@ -1,11 +1,14 @@
 # Represents an ingredient used within many recipes
 class Ingredient < ActiveRecord::Base
+  validates_presence_of :name
+
+  def recipe_linked?(recipe_id)
+    Ingredient.where(id: id).where('? = ANY (recipe_ids)', recipe_id).any?
+  end
+
   def link_to_recipe!(recipe_id)
     tap do |i|
-      if Ingredient.where(id: i.id).where('? = ANY (recipe_ids)', recipe_id)
-          .any?
-        fail 'Already Linked'
-      end
+      fail 'Already Linked' if recipe_linked?(recipe_id)
 
       i.recipe_frequency += 1
 

test/ingredient_test.rb

@@ -0,0 +1,28 @@
+require_relative './test_helper'
+require_relative '../models/ingredient.rb'
+
+describe Ingredient do
+  it 'requires a name' do
+    assert_raises(ActiveRecord::RecordInvalid) { Ingredient.new.save! }
+  end
+
+  it 'can be linked to a recipe' do
+    ingredient = Ingredient.new(name: 'mock_ingredient')
+      .tap { |i| i.recipe_ids = [] }
+
+    # Mocking postgres behaviour for the newly-created instance:
+    #   The "already linked" check
+        def ingredient.recipe_linked?(id); false end
+    #   The int[] field of recipe ids
+      ingredient.instance_variable_set :@recipe_ids, []
+      def ingredient.recipe_ids; @recipe_ids end
+
+    assert_equal 0, ingredient.recipe_frequency
+
+    RECIPE_ID = 10
+    ingredient.link_to_recipe!(RECIPE_ID)
+
+    assert_equal 1, ingredient.recipe_frequency
+    assert_equal [RECIPE_ID], ingredient.recipe_ids
+  end
+end

test/test_helper.rb

@@ -1,5 +1,18 @@
-  require 'codeclimate-test-reporter'
-  CodeClimate::TestReporter.start
+require 'codeclimate-test-reporter'
+CodeClimate::TestReporter.start
 
-  require 'minitest/spec'
-  require 'minitest/autorun'
+require 'minitest/spec'
+require 'minitest/autorun'
+
+require_relative '../environment.rb'
+
+# Mocking out Rails.root so that nulldb/rails plays nicely with MiniTest
+module Rails
+  module_function
+  def root
+    __dir__ + '/../'
+  end
+end
+require 'nulldb/rails'
+
+ActiveRecord::Base.establish_connection adapter: :nulldb, schema: './db/schema.rb'