Add Account Model specs (#341)

db/migrate/20191202173004_add_not_null_constraint_to_account_name.rb

@@ -0,0 +1,5 @@
+class AddNotNullConstraintToAccountName < ActiveRecord::Migration[6.0]
+  def change
+    change_column_null :accounts, :name, false
+  end
+end

db/schema.rb

@@ -10,13 +10,13 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 2019_11_26_185833) do
+ActiveRecord::Schema.define(version: 2019_12_02_173004) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
 
   create_table "accounts", id: :serial, force: :cascade do |t|
-    t.string "name"
+    t.string "name", null: false
     t.datetime "created_at", null: false
     t.datetime "updated_at", null: false
   end